71M6545T/71M6545HT Energy Meter ICs
General Description
The 71M6545T/71M6545HT metrology processors are
based on Maxim Integrated’s 4th-generation metering
architecture supporting the 71M6xxx series of isolated
current sensing products that offer drastic reduction in
component count, immunity to magnetic tampering, and
unparalleled reliability. The 71M6545T/71M6545HT inte-
grate our Single Converter Technology® with a 22-bit
delta sigma ADC, a customizable 32-bit computation
engine (CE) for core metrology functions, as well as a
user-programmable 8051-compatible application proces-
sor (MPU) core with 64KB flash and 5KB RAM.
An external host processor can access metrology func-
tions directly through the SPI interface, or alternatively
through the embedded MPU core in applications requir-
ing metrology data capture, storage, and preprocessing
within the metrology subsystem. In addition, the devices
integrate an RTC, DIO, and UART. A complete array of
ICE and development tools, programming libraries, and
reference designs enable rapid development and certi-
fication of meters that meet all ANSI and IEC electricity
metering standards worldwide.
The 71M6545T/71M6545HT operate over the industrial tem-
perature range and come in a 64-pin lead(Pb)-free package.
Applications
● Three-PhaseResidential,Commercial,andIndustrial
Energy Meters
Benets and Features
● SoCIntegrationandUniqueIsolationTechnique
Reduces BOM Cost Without Sacrificing Performance
• 0.1% Typical Accuracy Over 2000:1 Current
Range
• Exceeds IEC 62053/ANSI C12.20 Standards
• Four-Quadrant Metering
• 46-64Hz Line Frequency Range with the Same
Calibration
• Phase Compensation (±10º)
• Independent 32-Bit Compute Engine
• 64KB Flash, 5KB RAM
• Built-In Flash Security
• SPI Interface to Host with Flash Program
Capability
• Up to Four Pulse Outputs with Pulse Count
• 8-Bit MPU (80515), Up to 5 MIPS (Optional Use)
• Full-Speed MPU Clock in Brownout Mode
• Up to 29 Multifunction DIO Pins
• Hardware Watchdog Timer (WDT)
• UART for AMR or Other Communication Duties
• I2C/MICROWIRE® EEPROM Interface
● InnovativeIsolationTechnology(Requires
Companion 71M6xxx Sensor, also from Maxim
Integrated) Eliminates Current Transformers
• Four Current Sensor Inputs with Selectable
Differential Mode
• Selectable Gain of 1 or 8 for One Current Input to
Support Neutral Current Shunt
• High-Speed Wh/VARh Pulse Outputs with
Programmable Width
● DigitalTemperatureCompensationImprovesSystem
Performance
• Metrology Compensation
• Accurate RTC for TOU Functions with Automatic
Temperature Compensation for Crystal in All
Power Modes
● PowerManagementExtendsBatteryLifeDuring
Power Outages
• Two Battery-Backup Modes
- Brownout Mode (BRN)
- Sleep Mode (SLP)
• Wake-Up on Pin Events and Wake-On Timer
• 1µA in Sleep Mode
19-6721; Rev 5; 12/15
Ordering Information and Typical Operating Circuit appear
at end of data sheet.
Single Converter Technology is a registered trademark of
Maxim Integrated Products, Inc.
MICROWIRE is a registered trademark of National
Semiconductor Corp.
EVALUATION KIT AVAILABLE
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TABLE OF CONTENTS
General Description ............................................................................ 1
Applications .................................................................................. 1
Benefits and Features .......................................................................... 1
Absolute Maximum Ratings ...................................................................... 7
Electrical Characteristics ........................................................................ 7
Recommended External Components............................................................. 12
Pin Configuration ............................................................................. 13
Pin Descriptions .............................................................................. 14
Block Diagram ............................................................................... 17
Hardware Description.......................................................................... 18
Analog Front-End (AFE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Signal Input Pins .........................................................................20
Input Multiplexer..........................................................................21
Delay Compensation ......................................................................22
ADC Preamplifier .........................................................................23
Analog-to-Digital Converter (ADC) ...........................................................23
FIR Filter ...............................................................................23
Voltage References .......................................................................23
Isolated Sensor Interface...................................................................24
Digital Computation Engine (CE) ...............................................................24
Meter Equations ..........................................................................24
Real-Time Monitor ........................................................................24
Pulse Generators .........................................................................25
XPULSE and YPULSE.....................................................................25
VPULSE and WPULSE ....................................................................25
80515 MPU Core............................................................................25
Memory Organization and Addressing ........................................................25
Program Memory .........................................................................26
MPU External Data Memory (XRAM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
MOVX Addressing ........................................................................26
Dual Data Pointer.........................................................................27
Internal Data Memory Map and Access .......................................................27
Special Function Registers .................................................................27
Timers and Counters ......................................................................27
Interrupts ...............................................................................29
Interrupt Overview ........................................................................29
External MPU Interrupts ...................................................................30
On-Chip Resources .........................................................................30
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TABLE OF CONTENTS (continued)
Flash Memory ...........................................................................30
MPU/CE RAM ...........................................................................30
I/O RAM ................................................................................30
Crystal Oscillator .........................................................................31
PLL ....................................................................................31
Real-Time Clock (RTC) ....................................................................31
RTC Trimming ...........................................................................31
RTC Interrupts ...........................................................................31
Temperature Sensor ......................................................................31
Battery Monitor...........................................................................32
Digital I/O ...............................................................................32
EEPROM Interface .......................................................................32
Two-Pin EEPROM Interface ................................................................32
Three-Wire EEPROM Interface ..............................................................32
UART ..................................................................................33
SPI Slave Port ...........................................................................33
SPI Safe Mode...........................................................................33
SPI Flash Mode (SFM).....................................................................33
Hardware Watchdog Timer .................................................................33
Test Ports ...............................................................................33
Functional Description ......................................................................... 35
Theory of Operation .........................................................................35
Battery Modes..............................................................................35
Brownout Mode ..........................................................................36
Sleep Mode .............................................................................36
Applications Information........................................................................ 36
Connecting 5V Devices ......................................................................36
Direct Connection of Sensors..................................................................36
Using the 71M6545T/HT with Local Sensors ......................................................36
Using the 71M6545T/HT with Remote Sensors ....................................................37
Metrology Temperature Compensation ..........................................................37
Connecting I2C EEPROMs....................................................................37
Connecting Three-Wire EEPROMs .............................................................37
UART.....................................................................................37
Reset .....................................................................................37
Emulator Port Pins ..........................................................................37
MPU Firmware Library .......................................................................37
Meter Calibration............................................................................42
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TABLE OF CONTENTS (continued)
Firmware Interface ............................................................................ 42
Overview: Functional Order ...................................................................42
I/O RAM Map: Details ........................................................................42
Reading the Info Page .......................................................................42
CE Interface Description......................................................................55
CE Program .............................................................................55
CE Data Format ..........................................................................55
Constants ...............................................................................55
Environment .............................................................................55
CE Calculations ..........................................................................56
CE Input Data ...........................................................................56
Status and Control ........................................................................56
Transfer Variables ........................................................................56
Pulse Generation .........................................................................56
CE Flow Diagrams ............................................................................ 57
Ordering Information .......................................................................... 64
Package Information .......................................................................... 64
Typical Operating Circuit ....................................................................... 65
Revision History .............................................................................. 66
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LIST OF FIGURES
Figure 1. I/O Equivalent Circuits ................................................................. 16
Figure 2. 71M6545T/HT Operating with Local Sensors ............................................... 19
Figure 3. 71M6545T/HT Operating with Remote Sensor for Neutral Current ............................... 20
Figure 4. Multiplexer Sequence with Neutral Channel and Remote Sensors ............................... 22
Figure 5. Multiplexer Sequence with Neutral Channel and Current Transformers ........................... 22
Figure 6. Waveforms Comparing Voltage, Current, Energy per Interval, and Accumulated Energy ............. 36
Figure 7. Typical Voltage Sense Circuit Using Resistive Divider ......................................... 38
Figure 8. Typical Current-Sense Circuit Using Current Transformer in a Single-Ended Configuration ........... 38
Figure 9. Typical Current-Sense Circuit Using Current Transformer in a Differential Configuration.............. 38
Figure 10. Typical Current-Sense Circuit Using Shunt in a Differential Configuration ........................ 38
Figure 11. 71M6545T/HT Typical Operating Circuit Using Locally Connected Sensors ....................... 39
Figure 12. 71M6545T/HT Typical Operating Circuit Using Remote Neutral Current Sensor ................... 40
Figure 13. Typical I2C Operating Circuit ............................................................41
Figure 14. Typical UART Operating Circuit ..........................................................41
Figure 15. Typical Reset Circuits ..................................................................41
Figure 16. Typical Emulator Connections ...........................................................41
Figure 17. CE Data Flow—Multiplexer and ADC ..................................................... 63
Figure 18. CE Data Flow—Offset, Gain, and Phase Compensation ..................................... 63
Figure 19. CE Data Flow—Squaring and Summation ................................................. 64
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LIST OF TABLES
Table 1. ADC Input Configuration ................................................................ 23
Table 2. Inputs Selected in Multiplexer Cycles ...................................................... 25
Table 3. CKMPU Clock Frequencies .............................................................. 26
Table 4. Memory Map ......................................................................... 26
Table 5. Internal Data Memory Map .............................................................. 27
Table 6. Special Function Register Map ........................................................... 28
Table 7. Generic 80515 SFRs: Location and Reset Values ............................................. 28
Table 8. Timers/Counters Mode Description ........................................................ 29
Table 9. External MPU Interrupts................................................................. 30
Table 10. Test Ports ........................................................................... 34
Table 11. Info Page Trim Fuses .................................................................. 43
Table 12. I/O RAM Locations in Numerical Order .................................................... 44
Table 13. I/O RAM Locations in Alphabetical Order .................................................. 47
Table 14. Power Equations...................................................................... 57
Table 15. CE Raw Data Access Locations ......................................................... 57
Table 16. CE Status Register.................................................................... 58
Table 17. CE Configuration Register .............................................................. 58
Table 18. Sag Threshold and Gain Adjustment Registers.............................................. 59
Table 19. CE Transfer Registers ................................................................. 59
Table 20. CE Pulse Generation Parameters ........................................................ 60
Table 21. Other CE Parameters.................................................................. 61
Table 22. CE Calibration Parameters ............................................................. 62
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Electrical Characteristics
(All voltages referenced to GNDA.)
Supplies and Ground Pins
VV3P3SYS, VV3P3A ............................................... -0.5V to +4.6V
VBAT, VBAT_RTC...................................................-0.5V to +4.6V
GNDD ...................................................................-0.1V to +0.1V
Analog Output Pins
VREF .......................-10mA to +10mA, -0.5V to (VV3P3A + 0.5V)
VDD ..........................................-10mA to +10mA, -0.5V to +3.0V
VV3P3D ....................................-10mA to +10mA, -0.5V to +4.6V
Analog Input Pins
IADC0-7, VADC8-10 ........................... -10mA to +10mA, -0.5V to
(VV3P3A + 0.5V)
XIN, XOUT...............................-10mA to +10mA, -0.5V to +3.0V
DIO Pins
Configured as Digital Inputs ....-10mA to +10mA, -0.5V to +6.0V
Configured as Digital Outputs ............-10mA to +10mA, -0.5V to
(VV3P3D + 0.5V)
Digital Pins
Inputs (PB, RESET, RX, ICE_E, TEST) ...........-10mA to +10mA,
-0.5V to +6.0V
Outputs (TX) .......... -10mA to +10mA, -0.5V to (VV3P3D + 0.5V)
Temperature
Operating Junction Temperature (peak, 100ms) ............. +140°C
Operating Junction Temperature (continuous) ................ +125°C
Storage Temperature ........................................ -45°C to +140°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) ....................................... +260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Absolute Maximum Ratings
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
RECOMMENDED OPERATING CONDITIONS
VV3P3SYS and VV3P3A Supply
Voltage Precision metering operation 3.0 3.6 V
VBAT
PLL_FAST = 1 2.65 3.8 V
PLL_FAST = 0 2.40 3.8
VBAT_RTC 2.0 3.8 V
Operating Temperature -40 +85 °C
INPUT LOGIC LEVELS
Digital High-Level Input Voltage
(VIH)2 V
Digital Low-Level Input Voltage
(VIL)0.8 V
Input Pullup Current, (IIL) E_
RTXT, E_RST, E_TCLK 10 100 µA
Input Pullup Current, (IIL) OPT_
RX, OPT_TX 10 100 µA
Input Pullup Current, (IIL) SPI_
CSZ (SEGDIO36) 10 100 µA
Input Pullup Current, (IIL) Other
Digital Inputs -1 +1 µA
Input Pulldown Current (IIH),
ICE_E, RESET, TEST 10 100 µA
Input Pulldown Current, (IIH)
Other Digital Inputs -1 +1 µA
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Electrical Characteristics (continued)
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
OUTPUT LOGIC LEVELS
Digital High-Level Output
Voltage (VOH)
ILOAD = 1mA VV3P3D - 0.4 V
ILOAD = 15mA (Note 1) VV3P3D - 0.8 V
Digital Low-Level Output
Voltage (VOL)
ILOAD = 1mA 0 0.4 V
ILOAD = 15mA (Note 1) 0 0.8 V
BATTERY MONITOR
Battery Voltage Equation: 3.3 + (BSENSE - BNOM3P3) x 0.0252 + STEMP x 2.79E-5 V
Measurement Error
VBAT = 2.0V -3.5 +3.5
%
VBAT = 2.5V -3.5 +3.5
VBAT = 3.0V -3.0 +3.0
VBAT = 3.8V -3.0 +3.0
Input Impedance 260 kΩ
Passivation Current IBAT(BCURR = 1) – IBAT(BCURR = 0) 50 100 165 µA
TEMPERATURE MONITOR
Temperature Measurement
Equation
22.15 + STEMP x 0.085
- 0.0023 x STEMP x
[(STEMPT85P - STEMPT22P)/
(T85P - T22P) - 12.857]
°C
Temperature Error
(Note 1)
TA = +85°C -3.2 +3.2
°C
TA = 0°C to +70°C -2.65 +2.65
TA = -20°C -3.4 +3.4
TA = -40°C -3.8 +3.8
VBAT_RTC Charge per
Measurement 2 µC
Duration of Temperature
Measurement after TEMP_
START
22 40 ms
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Electrical Characteristics (continued)
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
SUPPLY CURRENT
VV3P3A + VV3P3SYS Supply
Current (Note 1)
VV3P3A = VV3P3SYS = 3.3V; MPU_DIV = 3 (614kHz
MPU clock); PLL_FAST = 1; PRE_E = 0 5.5 6.7
mA
PLL_FAST = 0 2.6 3.5
PRE_E = 1 5.7 6.9
PLL_FAST = 0, PRE_E=1 2.6 3.6
Dynamic Current 0.4 0.6 mA/MHz
VBAT Current
Mission mode -300 +300 nA
Brownout mode 2.4 3.2 mA
Sleep mode -300 +300 nA
VBAT_RTC Current
Brownout mode 400 650 nA
Sleep mode, TA≤25°C 0.7 1.7 µA
Sleep mode, TA = 85°C (Note 1) 1.5 3.2 µA
Flash Write Current Maximumashwriterate 7.1 9.3 mA
VV3P3D SWITCH
On-Resistance VV3P3SYS to VV3P3D, IV3P3D≤1mA 11 Ω
VBAT to VV3P3D, IV3P3D≤1mA 11
IOH 9 mA
INTERNAL POWER FAULT COMPARATOR
Response Time 100mV overdrive, falling 20 200 µs
100mV overdrive, rising 200
Falling Threshold, 3.0V
Comparator 2.83 2.93 3.03 V
Falling Threshold, 2.8V
Comparator 2.71 2.81 2.91 V
Difference between 3.0V and
2.8V comparators 47 136 220 mV
Falling Threshold, 2.25V
Comparator 2.14 2.33 2.51 V
Falling Threshold, 2.0V
Comparator 1.90 2.07 2.23 V
Difference between 2.25V and
2.0V Comparators 0.15 0.25 0.365 V
Hysteresis TA = +22°C
3.0V comparator 13 45 81
mV
2.8V comparator 17 42 79
2.25V comparator 7 33 71
2.0V comparator 4 28 83
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Electrical Characteristics (continued)
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
2.5V REGULATOR
VV2P5 Output Voltage VV3P3 = 3.0V to 3.8V, ILOAD = 0mA 2.55 2.65 2.75 V
VV2P5 Load Regulation VBAT = 3.3V, VV3P3 = 0V, ILOAD = 0mA to 1mA 40 mV
Dropout Voltage ILOAD = 5mA 440 mV
ILOAD = 0mA 200
PSSR ILOAD = 0mA 5 mV/V
CRYSTAL OSCILLATOR
Maximum Output Power to
Crystal 1 µW
PLL
PLL Settling Time
Power-up 3
ms
PLL_FAST transition, low to high 3
PLL_FAST transition, high to low 3
Mode transition, sleep to mission 3
VREF
VREF Output Voltage TA = +22°C 1.193 1.195 1.197 V
VREF Output Impedance ILOAD = -10µA to +10µA 3.2 kΩ
VREF Power Supply Sensitivity VV3P3A = 3.0V to 3.6V -1.5 +1.5 mV/V
VREF Temperature Sensitivity
(Note 1)
VREFT = VREF22 + (T-22)TC1
+ (T-22)2TC2
V
For 71M6545T TC1 = 151 - 2.77 x TRIMT µV/°C
For 71M6545HT
TC1 = 33.264 + 0.08 x TRIMT
+ 1.587 x (TRIMBGB -
TRIMBGD)
µV/°C
TC2 = -0.528 - 0.00128 x
TRIMT µV/°C2
VREF Error (Note 1)
71M6545T (-40°C to +85°C) -40 +40
ppm/°C71M6545HT (-40°C to -20°C) -16 +16
71M6545HT (-20°C to +85°C) -10 +10
ADC
Recommended Input Range
(All Analog Inputs, Relative to
VV3P3A)
-250 +250 mV Peak
Recommended Input Range,
IADC0-IADC1, Preamp Enabled -31.25 +31.25 mV Peak
Input Impedance fIN = 65Hz 40 100 kΩ
ADC Gain Error vs. Power
Supply VIN = 200mV peak, 65Hz, VV3P3A = 3.0V to 3.6V -30 +70 ppm/%
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Electrical Characteristics (continued)
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Offset Voltage Differential or single-ended modes -10 +10 mV
THD
250mV peak, 65Hz, 64k points, Blackman-Harris
window, FIR_LEN = 2, ADC_DIV = 1, PLL_FAST = 1,
MUX_DIV = 2
-93
dB
20mV peak, 65Hz, 64k points, Blackman-Harris
window, FIR_LEN = 2, ADC_DIV = 1, PLL_FAST = 1,
MUX_DIV = 2
-90
LSB Size FIR_LEN = 2, ADC_DIV = 1, PLL_FAST = 1, MUX_
DIV = 2 151 nV
Digital Full Scale FIR_LEN = 2, ADC_DIV = 1, PLL_FAST = 1, MUX_
DIV = 2 ±2,097,152 LSB
PREAMPLIFIER
Differential Gain 7.88 7.98 8.08 V/V
Gain Variation vs. Temperature TA = -40°C to +85°C (Note 1) -30 -10 +15 ppm/°C
Gain Variation vs. V3P3 VV3P3 = 2.97V to 3.63V (Note 1) -100 +100 ppm/%
Phase Shift (Note 1) +10 +22 m°
Preamp Input Current 3 6 9 µA
THD, Preamp + ADC VIN = 30mV -88 dB
VIN = 15mV -88
Preamp Input Offset Voltage
IADC0 = IADC1 = VV3P3 + 30mV -0.63
mV
IADC0 = IADC1 = VV3P3 + 15mV -0.57
IADC0 = IADC1 = VV3P3 -0.56
IADC0 = IADC1 = VV3P3 - 15mV -0.56
IADC0 = IADC1 = VV3P3 - 30mV -0.55
Phase Shift Over Temperature (Note 1) -0.03 +0.03 m°/C
FLASH MEMORY
Endurance 20,000 Cycles
Data Retention TA = +25°C 100 Years
Byte Writes Between Erase
Operations 2 Cycles
Write Time, per Byte Per 2 bytes if using SPI 50 µs
Page Erase Time 22 ms
Mass Erase Time 22 ms
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Electrical Characteristics (continued)
Recommended External Components
Note 1: Parameter not tested in production, guaranteed by design to six-sigma.
Note 2: If the capacitor values of CXS = 15pF and CXL = 10pF have already been installed, then changing the CXL value to 33pF
and leaving CXS = 15pF would minimize rework.
(Limits are production tested at TA = +25ºC. Limits over the operating temperature range and relevant supply voltage range are guar-
anteed by design and characterization.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
SPI
Data-to-Clock Setup Time 10 ns
Data Hold Time From Clock 10 ns
Output Delay, Clock to Data 40 ns
CS-to-Clock Setup Time 10 ns
Hold Time, CS to Clock 15 ns
Clock High Period 40 ns
Clock Low Period 40 ns
Clock Frequency (as a Multiple
of CPU Frequency) 2.0 MHz/MHz
Space Between SPI
Transactions 4.5 CPU
Cycles
EEPROM INTERFACE
I2C SCL Frequency MPU clock = 4.9MHz, using interrupts 310 kHz
MPU clock = 4.9MHz, bit-banging DIO2-DIO3 100
3-Wire Write Clock Frequency MPU clock = 4.9MHz, PLL_FAST = 0 160 kHz
MPU clock = 4.9MHz, PLL_FAST = 1 490
RESET
Reset Pulse Width (Note 1) 5 µs
Reset Pulse Fall Time (Note 1) 1 µs
INTERNAL CALENDAR
Year Date Range 2000 2255 Years
NAME FROM TO FUNCTION VALUE UNITS
C1 VV3P3A GNDA Bypass capacitor for 3.3V supply ≥0.1±20% µF
C2 VV3P3D GNDD Bypass capacitor for 3.3V output 0.1 ±20% µF
CSYS VV3P3SYS GNDD Bypass capacitor for VV3P3SYS ≥1.0±30% µF
CVDD VDD GNDD Bypass capacitor for VDD 0.1 ±20% µF
XTAL XIN XOUT
32.768 kHz crystal; electrically similar to ECS
.327-12.5-17X, Vishay XT26T or Suntsu SCP6–
32.768kHz TR (load capacitance 12.5pF)
32.768 kHz
CXS
(Note 2) XIN GNDA Load capacitor values for crystal depend on crystal
specicationsandboardparasitics.Nominal
values are based on 3pF allowance for the sum
of board capacitance and chip capacitance.
22 ±10% pF
CXL
(Note 2) XOUT GNDA 22 ±10% pF
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Pin Conguration
71M6545T
71M6545HT
LQFP
TOP VIEW
SPI_DO
VDD
VV3P3D
DIO29
DIO28
SPI_DI
12 4567
DIO1/VPULSE
DIO2/SDCK
DIO3/SDATA
DIO4
SPI_CSZ
3
DIO5
DIO6/XPULSE
DIO7/YPULSE
DIO8/DI
DIO9
DIO10
DIO11
DIO12
DIO13
DIO14
DIO0/WPULSE
DIO55
TEST
VADC10 (VC)
VADC9 (VB)
VADC8 (VA)
VV3P3A
IADC1
IADC0
VREF
N.C.
PB
RESET
TMUXOUT
TMUX2OUT
SPI_CKI
GNDA
XOUT
30
29
28
27
26
25
24
23
22
21
20
19
18
17
31
32
51
52
53
54
55
56
57
58
59
60
61
62
63
64
50
49
DIO25
DIO24
DIO23
DIO22
DIO21
DIO20
DIO19
TX
GNDD
GNDA
VV3P3SYS
IADC2
IADC3
IADC4
XIN
VBAT_RTC
IADC5
IADC6
IADC7
GNDD
ICE_E
E_RXTX
E_TCLK
E_RST
RX
8910 11 12 13 14 15 16
48 47 45 44 43 4246 41 40 39 38 37 36 35 34 33
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Pin Descriptions
PIN NAME TYPE CIRCUIT FUNCTION
POWER AND GROUND PINS
47, 50 GNDA P — Analog Ground. This pin should be connected directly to the ground plane.
16, 38 GNDD P — Digital Ground. This pin should be connected directly to the ground plane.
55 VV3P3A P — Analog Power Supply. A 3.3V power supply should be connected to this pin.
VV3P3A must be the same voltage as VV3P3SYS.
45 VV3P3SYS P — System 3.3V supply. This pin should be connected to a 3.3V power supply.
5 VV3P3D O 13
Auxiliary Voltage Output of the Chip. In mission mode, this pin is connected
to VV3P3SYS by the internal selection switch. In BRN mode, it is internally
connected to VBAT. VV3P3DisoatinginLCDandsleepmode.A0.1µF
bypass capacitor to ground must be connected to this pin.
4 VDD O — Output of the 2.5V Regulator. This pin is powered in MSN and BRN modes. A
0.1µF bypass capacitor to ground should be connected to this pin.
46 VBAT_RTC P 12
RTC and Oscillator Power Supply. A battery or super capacitor is to be
connected between VBAT and GNDD. If no battery is used, connect VBAT_
RTC to VV3P3SYS.
ANALOG PINS
57, 56 IADC0
IADC1
I 6
Differential or Single-Ended Line Current Sense Inputs. These pins are
voltage inputs to the internal A/D converter. Typically, they are connected to
the outputs of current sensors. Unused pins must be tied to VV3P3A. Pins
IADC2-IADC3,IADC4-IADC5andIADC6-IADC7maybeconguredfor
communication with the remote sensor interface (71M6x03).
44, 43 IADC2
IADC3
42, 41 IADC4
IADC5
40, 39 IADC6
IADC7
54, 53, 52
VADC8 (VA),
VADC9 (VB),
VADC10 (VC)
I 6
Line Voltage Sense Inputs. These pins are voltage inputs to the internal A/D
converter. Typically, they are connected to the outputs of resistor-dividers.
Unused pins must be tied to VV3P3A.
58 VREF O 9 VoltageReferencefortheADC.Thispinshouldbeleftunconnected(oating).
48 XIN I
8
Crystal Inputs. A 32.768kHz crystal should be connected across these pins.
Typically, a 22pF capacitor is also connected from XIN to GNDA and a 22pF
capacitor is connected from XOUT to GNDA. It is important to minimize the
capacitance between these pins. See the crystal manufacturer data sheet
for details. If an external clock is used, a 150mVP-P clock signal should be
applied to XIN, and XOUT should be left unconnected.
49 XOUT O
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Pin Descriptions (continued)
I = Input, O = Output, P = Power
PIN NAME TYPE CIRCUIT FUNCTION
DIGITAL PINS
31 DIO0/WPULSE
I/O 3
Multiple-Use Pins. Alternative functions with proper selection of associated
I/O RAM registers are:
DIO0 = WPULSE
DIO1 = VPULSE
DIO2 = SDCK
DIO3 = SDATA
DIO6 = XPULSE
DIO7 = YPULSE
DIO8 = DI
DIO16 = RX3
DIO17 = TX3
UnusedpinsmustbeconguredasoutputsorterminatedtoV3P3/GNDD.
30 DIO1/VPULSE
29 DIO2/SDCK
28 DIO3/SDATA
27 DIO4
26 DIO5
25 DIO6/XPULSE
24 DIO7/YPULSE
23 DIO8/DI
22-17 DIO[9:14]
14-8 DIO[19:25]
7-6 DIO[28:29]
3 SPI_CSZ
I/O 3 SPI Interface
2 SPI_DO
1 SPI_DI
64 SPI_CKI
32 DIO55 I/O 3 DIO
36 E_RXTX I/O 1 Emulator Port Pins
34 E_RST
35 E_TCLK O 4
37 ICE_E I 2 ICE Enable. For production units, this pin should be pulled to GND to disable
the emulator port.
62 TMUXOUT O 4, 5 Multiplexer/Clock Output
63 TMUX2OUT
61 RESET I 2
Chip Reset. This input pin is used to reset the chip into a known state. For
normal operation, this pin is pulled low. To reset the chip, this pin should be
pulled high. This pin has an internal 30FA (nominal) current source pulldown.
No external reset circuitry is necessary.
33 RX I 3 UART Input. If this pin is unused it must be terminated to VV3P3D or GNDD.
15 TX O 4 UART Output
51 TEST I 7 Enables Production Test. This pin must be grounded in normal operation.
60 PB I 3
Pushbutton Input. This pin must be at GNDD when not active or unused. A
risingedgesetstheWF_PBag.Italsocausestheparttowakeupifitisin
SLP mode. PB does not have an internal pullup or pulldown resistor.
59 N.C. N.C. — No Connection. Do not connect these pins.
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Figure 1. I/O Equivalent Circuits
DIGITAL INPUT EQUIVALENT CIRCUIT
TYPE 1:
STANDARD DIGITAL INPUT OR
PIN CONFIGURED AS DIO INPUT
WITH INTERNAL PULL-UP
V3P3D V3P3D
110kΩ
CMOS
INPUT
DIGITAL
INPUT
PIN
DIGITAL INPUT
TYPE 2:
PIN CONFIGURED AS DIO INPUT
WITH INTERNAL PULL-UP
V3P3D
110kΩ
CMOS
INPUT
DIGITAL
INPUT
PIN
GNDD
GNDD
ANALOG INPUT EQUIVALENT CIRCUIT
TYPE 6:
ADC INPUT
VREF EQUIVALENT CIRCUIT
TYPE 9:
VREF
V3P3D
VREF
PIN
FROM
INTERNAL
REFERENCE
GNDA
V2P5 EQUIVALENT CIRCUIT
TYPE 10:
V2P5
V3P3D
V2P5
PIN
FROM
INTERNAL
REFERENCE
GNDD
V3P3D
TO
MUX
ANALOG
INPUT
PIN
GNDA
DIGITAL INPUT
TYPE 3:
STANDARD DIGITAL INPUT OR
PIN CONFIGURED AS DIO INPUT
V3P3D
CMOS
INPUT
DIGITAL
INPUT
PIN
GNDD
DIGITAL OUTPUT EQUIVALENT CIRCUIT
TYPE 4:
STANDARD DIGITAL OUTPUT OR
PIN CONFIGURED AS DIO OUTPUT
V3P3D
V3P3D
CMOS
OUTPUT
DIGITAL
OUTPUT
PIN
GNDD
COMPARATOR INPUT EQUIVALENT CIRCUIT
TYPE 7:
COMPARATOR INPUT
V3P3D
TO
COMPARATOR
COMPARATOR
INPUT
PIN
GNDA
V3P3D EQUIVALENT CIRCUIT
TYPE 13:
V3P3D
OSCILLATOR EQUIVALENT CIRCUIT
TYPE 8:
OSCILLATOR I/O
TO
OSCILLATOR
OSCILLATOR
PIN
GNDD
VBAT EQUIVALENT CIRCUIT
TYPE 12:
VBAT POWER
POWER
DOWN
CIRCUITS
VBAT
PIN
GNDD
10Ω
40Ω
V3P3D
PIN
FROM
V3P3SYS
FROM
VBAT
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Block Diagram
IADC5 MUX
AND
PREAMP
XIN
XOUT
VREF
CKADC
CE
MPU
(80515)
RESET
VBIAS
EMULATOR
PORT
3
CE_BUSY
UART0
TX
RX
XFER BUSY
CEDATA
0x000...0x2FF
0x0000...0x13FF
PROG
0x000...0x3FF
DATA
0x0000...0xFFFF
PROGRAM
0x0000...0xFFFF
0x0000...
0xFFFF
DIGITAL I/O
0x2000...0x20FF
I/O RAM
MEMORY
SHARE
MEMORY
SHARE
16
8
RTCLK
RTCLK (32kHz)
MUX_SYNC
CKMPU
≤4.9MHz
CKCE
≤4.9MHz
CK32
32kHz
4.9MHz
4.9MHz
8
8
8
POWER FAULT
DETECTION
GNDD
V3P3D
VOLTAGE
REGULATOR
2.5V TO LOGIC
VDD
MPU_RSTZ
FAULTZ
WAKE
CONFIGURATION
PARAMETERS
GNDAGNDA
VBIAS
CROSS
CLOCK GEN
OSCILLATOR
32kHz
CK32
MCK
PLL
VREF
DIV
ADC
MUX CTRL
STRT
MUX
MUX
CKFIR
RTM
SPI_I/F
WPULSE
VARPULSE
WPULSE
VARPULSE
TEST TEST
MODE
CKMPU_2x
CKMPU_2x
SDCK
SDOUT
SDIN
E_RXTX
E_TCLK
E_RST
FLASH
64KB
V3P3A
EEPROM
INTERFACE
CK_4X
PB
RTC
VBIAS
16
E_RXTX
E_TCLK
E_RST
ICE_E
∆∑
AD CONVERTER
VREF
V3P3SYS
TEST MUX
GNDD
MPU RAM
3.5KB
22
SPI
VSTAT
VBAT_RTC
IADC6
IADC7
VADC8
VADC9
VADC10
TEST MUX
2
NON-VOLATILE
CONFIGURATION
RAM
CONFIGURATION
RAM
(I/O RAM)
BAT
TEST
TEMP
SENSOR
RTM
FIR
32
CE CONTROL
32-BIT
COMPUTE
ENGINE
DIO PINS
V3P3A
IADC1
IADC2
IADC3
IADC4
IADC0
TMUXOUT TMU2XOUT
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Hardware Description
The 71M6545T/HT single-chip energy meter ICs integrate
all primary functional blocks required to implement a
solid-state residential electricity meter. Included on the
chip are the following:
• An analog front-end (AFE) featuring a 22-bit second-
order sigma-delta ADC
• An independent 32-bit digital computation engine (CE)
to implement DSP functions
• An 8051-compatible microprocessor (MPU) which
executes one instruction per clock cycle (80515)
• A precision voltage reference (VREF)
• A temperature sensor for digital temperature compensation:
• Metrology digital temperature compensation (MPU)
• Automatic RTC digital temperature compensation
operational in all power states
• RAM and flash memory
• A real-time clock (RTC)
• A variety of I/O pins
• A power-failure interrupt
• A zero-crossing interrupt
• Selectable current sensor interfaces for locally-connect-
ed sensors as well as isolated sensors (i.e., using the
71M6x03 companion IC with a shunt resistor sensor)
• Resistive shunt and current transformers are supported
Resistive shunts and current transformer (CT) current
sensors are supported. Resistive shunt current sensors
may be connected directly to the 71M654xT device
or isolated using a companion 71M6x03 isolator IC in
order to implement a variety of metering configurations.
An inexpensive, small pulse transformer is used to
isolate the 71M6x03 isolated sensor from the 71M654xT.
The 71M654xT performs digital communications
bidirectionally with the 71M6x03 and also provides power
to the 71M6x03 through the isolating pulse transformer.
Isolated (remote) shunt current sensors are connected
to the differential input of the 71M6x03. Included on the
71M6x03 companion isolator chip are:
• Digital isolation communications interface
• An analog front-end (AFE)
• A precision voltage reference (VREF)
• A temperature sensor (for digital temperature compen-
sation)
• A fully differential shunt resistor sensor input
• A preamplifier to optimize shunt current sensor perfor-
mance
• Isolated power circuitry obtains dc power from pulses
sent by the 71M654xT
In a typical application, the 32-bit compute engine (CE)
of the 71M654xT sequentially processes the samples
from the voltage inputs on analog input pins and from
the external 71M6x03 isolated sensors and performs
calculations to measure active energy (Wh) and reactive
energy (VARh), as well as A2h, and V2h for four-quadrant
metering. These measurements are then accessed by the
MPU, processed further and output using the peripheral
devices available to the MPU.
In addition to advanced measurement functions, the clock
function allows the 71M6545T/HT to record time-of-use
(TOU) metering information for multi-rate applications and
to time-stamp tamper or other events.
In addition to the temperature-trimmed ultra-precision
voltage reference, the on-chip digital temperature
compensation mechanism includes a temperature sensor
and associated controls for correction of unwanted
temperature effects on measurement and RTC accuracy,
e.g., to meet the requirements of ANSI and IEC standards.
Temperature-dependent external components such as
crystal oscillator, resistive shunts, current transformers
(CTs) and their corresponding signal conditioning circuits
can be characterized and their correction factors can be
programmed to produce electricity meters with exceptional
accuracy over the industrial temperature range.
See the Block Diagram.
Analog Front-End (AFE)
The AFE functions as a data acquisition system, controlled
by the MPU. When used with locally connected sensors,
as shown in Figure 2, the analog input signals (IADC0-
IADC7, VADC8-VADC10) are multiplexed to the ADC
input and sampled by the ADC.
The ADC output is decimated by the FIR filter and stored
in CE RAM where it can be accessed and processed by
the CE.
When remote isolated sensors are connected to the
71M6545T/HT using 71M6x03 remote sensor interfaces,
the input multiplexer is bypassed. Instead, the extracted
modulator bit stream is passed directly to a dedicated
decimation filter. The output of the decimation filter is then
directly stored in the appropriate CE RAM location without
making use of a multiplexer cycle.
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Figure 2. 71M6545T/HT Operating with Local Sensors
∆∑ ADC
CONVERTER
VREF
MUX
VREF
VREF
VADC
22
FIR
IADC6
IADC0
VADC10 (VA)
IADC1
IADC7
71M6545T/HT
CE RAM
*IN = OPTIONAL NEUTRAL CURRENT
IN*
CT
VADC10 (VB)
VADC10 (VC)
I
A
IADC2
IADC3
I
B
IADC4
IADC5
I
C
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Figure 3. 71M6545T/HT Operating with Remote Sensor for Neutral Current
Signal Input Pins
The 71M6545T/HT features eleven ADC inputs.
IADC0-IADC7 are intended for use as current sensor
inputs. These eight current sensor inputs can be config-
ured as four single-ended inputs, or (more frequently) can
be paired to form four differential inputs. For best perfor-
mance, it is recommended to configure the current sen-
sor inputs as differential inputs. The first differential input
(IADC0-IADC1) features a preamplifier with a selectable
gain of 1 or 8, and is intended for direct connection to a
shunt resistor sensor, and can also be used with a current
transformer (CT). The remaining differential pairs may be
used with CTs, or may be enabled to interface to a remote
71M6x03 isolated current sensor providing isolation for a
shunt resistor sensor using a low cost pulse transformer.
The remaining inputs (VADC8-VADC10) are single-ended
and sense line voltage. These single-ended inputs are
referenced to the VV3P3A pin.
All analog signal input pins measure voltage. In the
case of shunt current sensors, currents are sensed as
a voltage drop in the shunt resistor sensor. Referring
to Figure 2, shunt sensors can be connected directly to
the 71M654xT (referred to as a ‘local’ shunt sensor) or
connected through an isolated 71M6x03 (referred to as a
‘remote’ shunt sensor) (Figure 3). In the case of current
transformers, the current is measured as a voltage across
a burden resistor that is connected to the secondary
winding of the CT. Meanwhile, line voltages are sensed
through resistive voltage dividers.
∆∑ ADC
CONVERTER
VREF
MUX
VREF
VREF
VADC 22
22
FIR
IADC0
VADC8 (VA)
IADC1
CE RAM
LOCAL
SHUNT
IN*
VADC9 (VB)
VADC10 (VC)
REMOTE
SHUNT
IC
71M6545T/HT
71M6x03
* IN = OPTIONAL NEUTRAL CURRENT
IADC6
IADC7
SP
SN
INP
INN
DIGITAL
ISOLATION
INTERFACE
22REMOTE
SHUNT
IB
71M6x03
IADC4
IADC5
SP
SN
INP
INN
DIGITAL
ISOLATION
INTERFACE
22REMOTE
SHUNT
IA
71M6x03
IADC2
IADC3
SP
SN
INP
INN
DIGITAL
ISOLATION
INTERFACE
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Pins IADC0-IADC1 can be programmed individually to be
differential or single-ended. For most applications IADC0-
IADC1 are configured as a differential input to work with
a shunt or CT directly interfaced to the IADC0-IADC1
differential input with the appropriate external signal con-
ditioning components.
The performance of the IADC0-IADC1 pins can be
enhanced by enabling a preamplifier with a fixed gain of 8.
When the PRE_E bit = 1, IADC0-IADC1 become the inputs
to the 8x preamplifier, and the output of this amplifier is
supplied to the multiplexer. The 8x amplification is useful
when current sensors with low sensitivity, such as shunt
resistors, are used. With PRE_E set, the IADC0-IADC1
input signal amplitude is restricted to 31.25 mV peak.
When shunt resistors are used as current sense ele-
ments on all current inputs, the IADC0-IADC1 pins are
configured for differential mode to interface to a local
shunt by setting the DIFFA_E control bit. Meanwhile, the
IADC2-IADC7 pins are re-configured as digital balanced
pair to communicate with a 71M6x03 isolated sensor
interface by setting the RMT_E control bit. The 71M6x03
communicates with the 71M654xT using a bidirectional
digital data stream through an isolating low-cost pulse
transformer. The 71M654xT also supplies power to the
71M6x03 through the isolating transformer.
When using current transformers the IADC2-IADC7 pins
are configured as local analog inputs (RMT_E = 0). The
IADC0-IADC1 pins cannot be configured as a remote
sensor interface.
Input Multiplexer
When operating with local sensors, the input multiplexer
sequentially applies the input signals from the analog
input pins to the input of the ADC. One complete sam-
pling sequence is called a multiplexer frame. The multi-
plexer of the 71M6545T/HT can select up to seven input
signals (three voltage inputs and four current inputs) per
multiplexer frame. The multiplexer always starts at state
1 and proceeds until as many states as determined by
MUX_DIV[3:0] have been converted.
The 71M6545T/HT requires CE code that is written for
the specific application. Moreover, each CE code requires
specific AFE and MUX settings in order to function properly.
Contact Maxim Integrated for specific information about alter-
native CE codes.
For a polyphase configuration with neutral current sens-
ing using shunt resistor current sensors and the 71M6xx3
isolated sensors, as shown in Figure 3, the IADC0-IADC1
input must be configured as a differential input, to be con-
nected to a local shunt. The local shunt connected to the
IADC0-IADC1 input is used to sense the Neutral current.
The voltage sensors (VADC8-VADC10) are also directly
connected to the 71M6545T/HT and are also routed
though the multiplexer. Meanwhile, the IADC2-IADC7
current inputs are configured as remote sensor digital
interfaces and the corresponding samples are not routed
through the multiplexer.
For a polyphase configuration with optional neutral current
sensing using Current Transformer (CTs) sensors, all four
current sensor inputs must be configured as differential
inputs. IADC2-IADC3 is connected to phase A, IADC4-
IADC5 is connected to phase B, and IADC6-IADC7
is connected to phase C. The IADC0-IADC1 current
sensor input is optionally used to sense the Neutral
current for anti-tampering purposes. The voltage sensors
(VADC8-VADC10), typically resistive dividers, are directly
connected to the 71M6545T/HT. No 71M6xx3 isolated
sensors are used in this configuration and all signals are
routed though the multiplexer.
The multiplexer sequence shown in Figure 4 corresponds
to the configuration shown in Figure 3. The frame duration
is 13 CK32 cycles (where CK32 = 32,768Hz), therefore,
the resulting sample rate is 32,768Hz/13 = 2,520.6Hz.
Note that Figure 4 only shows the currents that pass
through the 71M6545T/HT multiplexer, and does not show
the currents that are copied directly into CE RAM from the
remote sensors (see Figure 3), which are sampled during
the second half of the multiplexer frame. The two unused
conversion slots shown are necessary to produce the
desired 2,520.6Hz sample rate.
The multiplexer sequence shown in Figure 5 corresponds
to the CT configuration shown in Figure 2. Since in
this case all current sensors are locally connected to
the 71M6545T/HT, all currents are routed through the
multiplexer, as seen in Figure 2. For this multiplexer
sequence, the frame duration is 15 CK32 cycles (where
CK32 = 32,768Hz), therefore, the resulting sample rate is
32,768Hz/15 = 2,184.5Hz.
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Delay Compensation
When measuring the energy of a phase (i.e., Wh and
VARh) in a service, the voltage and current for that phase
must be sampled at the same instant. Otherwise, the
phasedifference,Ф,introduceserrors.
delay
delay
t
360 t f 360
T
ϕ= ⋅°= ⋅⋅°
Where f is the frequency of the input signal, T = 1/f and
tdelay is the sampling delay between current and voltage.
Tradition ally, sampling is accomplished by using two A/D
converters per phase (one for voltage and the other one
for current) controlled to sample simultaneously. Our
Single Converter Technology, however, ex ploits the 32-bit
signal processing capability of its CE to implement “con-
stant delay” allpass filters. The allpass filter corrects for
the conversion time difference between the voltage and
the corresponding current samples that are obtained with
a single multiplexed A/D converter.
The “constant delay” allpass filter provides a broad-band
delay360°–θ,whichispreciselymatchedtothediffer-
ence in sample time between the voltage and the current
of a given phase. This digital filter does not affect the
amplitude of the signal, but provides a precisely controlled
phase response.
Figure 4. Multiplexer Sequence with Neutral Channel and Remote Sensors
Figure 5. Multiplexer Sequence with Neutral Channel and Current Transformers
CK32
MUX STATE012345
SETTLE
MULTIPLEXER FRAME
MUX_DIV[3:0] = 6 CONVERSIONS
S
CROSS
MUX_SYNC
S
IN UNUSED UNUSED VA VB VC
CK32
MUX STATE0 12345
MUX_DIV[3:0] = 7 CONVERSIONS SETTLE
MULTIPLEXER FRAME
S
CROSS
MUX_SYNC
S6
IA VA IB VB IC VC IN
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The recommended ADC multiplexer sequence samples
the current first, immediately followed by sampling of the
corresponding phase voltage, thus the voltage is delayed
by a phase angle Ф relative to the current. The delay
compensation implemented in the CE aligns the voltage
samples with their corresponding current samples by first
delaying the current samples by one full sample interval
(i.e., 360°), then routing the voltage samples through
the allpass filter, thus delaying the voltage samples by
360o - θ, resulting in the residual phase error between
thecurrentanditscorrespondingvoltageofB–Ф.The
residual phase error is negligible, and is typically less than
±1.5 milli-degrees at 100Hz, thus it does not contribute to
errors in the energy measurements.
When using remote sensors, the CE performs the same
delay compensation described above to align each volt-
age sample with its corresponding current sample. Even
though the remote current samples do not pass through
the 71M654xT multiplexer, their timing relationship to their
corresponding voltages is fixed and precisely known.
ADC Preamplier
The ADC preamplifier is a low-noise differential ampli-
fier with a fixed gain of 8 available only on the IADC0-
IADC1 sensor input pins. A gain of 8 is enabled by setting
PRE_E = 1. When disabled, the supply current of the
preamplifier is < 10 nA and the gain is unity. With proper
settings of the PRE_E and DIFFA_E (I/O RAM 0x210C[4])
bits, the preamplifier can be used whether or not differen-
tial mode is selected. For best performance, the differential
mode is recommended. In order to save power, the bias
current of the preamplifier and ADC is adjusted according
to the ADC_DIV control bit (I/O RAM 0x2200[5]).
Analog-to-Digital Converter (ADC)
A single 2nd-order delta-sigma ADC digitizes the voltage
and current inputs to the device. The resolution of the
ADC, including the sign bit, is 21 bits (FIR_LEN[1:0] = 1),
or 22 bits (FIR_LEN[1:0] = 2).
Initiation of each ADC conversion is controlled by MUX_
CTRL internal circuit. At the end of each ADC conversion,
the FIR filter output data is stored into the CE RAM loca-
tion determined by the multiplexer selection. FIR data is
stored LSB justified, but shifted left 9 bits.
FIR Filter
The finite impulse response filter is an integral part of the
ADC and it is optimized for use with the multiplexer. The
purpose of the FIR filter is to decimate the ADC output to
the desired resolution. At the end of each ADC conver-
sion, the output data is stored into the fixed CE RAM
location determined by the multiplexer selection.
Voltage References
A bandgap circuit provides the reference voltage to the
ADC. The VREF band-gap amplifier is chopper-stabilized
to remove the dc offset voltage. This offset voltage is the
most significant long-term drift mechanism in voltage ref-
erence circuits.
Table 1. ADC Input Configuration
PIN REQUIRED
SETTING COMMENT
IADC0 DIFFx_E = 1 Differential mode must be selected with DIFFx_E = 1. The ADC results are stored in ADC0 and ADC1 is
not disturbed.
IADC1
IADC2 DIFFx_E = 1 or
RMT_E = 1
For locally connected sensors the differential input must be enabled.
For the remote sensor RMT_E must be set. ADC results are stored in ADC2 and ADC3 is not disturbed.
IADC3
IADC4 DIFFx_E = 1 or
RMT_E = 1
For locally connected sensors the differential input must be enabled.
For the remote sensor RMT_E must be set. ADC results are stored in ADC4 and ADC5 is not disturbed.
IADC5
IADC6 DIFFx_E = 1 or
RMT_E = 1
For locally connected sensors the differential input must be enabled.
For the remote sensor RMT_E must be set. ADC results are stored in ADC6 and ADC7 is not disturbed.
IADC7
VADC8 — Phase A voltage. Single ended mode only. ADC result stored in ADC8.
VADC9 — Phase B voltage. Single ended mode only. ADC result stored in ADC9.
VADC10 — Phase A voltage. Single ended mode only. ADC result stored in ADC10.
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Isolated Sensor Interface
Nonisolating sensors, such as shunt resistors, can be
connected to the inputs of the 71M654xT through a
combination of a pulse transformer and a 71M6x03
isolated sensor interface. The 71M6x03 receives power
directly from the 71M654xT through a pulse transformer
and does not require a dedicated power supply circuit.
The 71M6x03 establishes 2-way communication with
the 71M654xT, supplying current samples and auxiliary
information such as sensor temperature through a serial
data stream.
Up to three 71M6x03 isolated sensors can be supported
by the 71M6545T/HT. When a remote sensor interface is
enabled, the two analog current inputs become reconfig-
ured as a digital remote sensor interface. Each 71M6x03
isolated sensor consists of the following building blocks:
• Power supply for power pulses received from the
71M654xT
• Digital communications interface
• Shunt signal preamplifier
• Delta-sigma ADC converter with precision bandgap
reference (chopping amplifier)
• Temperature sensor
• Fuse system containing part-specific information
During an ordinary multiplexer cycle, the 71M654xT inter-
nally determines which other channels are enabled. At
the same time, it decimates the modulator output from the
71M6x03 isolated sensors. Each result is written to CE
RAM during one of its CE access time slots.
The ADC of the 71M6x03 derives its timing from the power
pulses generated by the 71M654xT and as a result, oper-
ates its ADC slaved to the frequency of the power pulses.
The generation of power pulses, as well as the commu-
nication protocol between the 71M654xT and 71M6x03
isolated sensor is au tomatic and transparent to the user.
The 71M654xT can read data and status from, and
can write control information to the 71M6x03 isolated
sensor. With hardware and trim-related information on
each connected 71M6x03 isolated sensor available to
the 71M6545T/HT, the MPU can implement temperature
compensation of the energy measurement based on the
individual temperature characteristics of the 71M6x03
isolated sensor.
Digital Computation Engine (CE)
The CE, a dedicated 32-bit signal processor, performs the
precision computations necessary to accurately measure
energy. The CE calculations and processes include:
• Multiplication of each current sample with its associ-
ated voltage sample to obtain the energy per sample
(when multiplied with the constant sample time).
• Frequency-insensitive delay cancellation on all four
channels (to compensate for the delay bet ween sam-
ples caused by the multiplexing scheme).
• 90° phase shifter (for VAR calculations).
• Pulse generation.
• Monitoring of the input signal frequency (for frequency
and phase information).
• Monitoring of the input signal amplitude (for sag detec-
tion).
• Scaling of the processed samples based on calibration
coefficients.
• Scaling of samples based on temperature compensa-
tion information.
Meter Equations
The 71M6545T/HT provides hardware assistance to the
CE in order to support various meter equations. The
compute engine firmware for industrial configurations
can implement the equations listed in Table 2. EQU[2:0]
specifies the equation to be used based on the meter con-
figuration and on the number of phases used for metering.
Real-Time Monitor
The CE contains a real-time monitor (RTM), which can be
programmed to monitor four selectable XRAM locations at
full sample rate. The four monitored locations are serially
output to the TMUXOUT pin via the digital output multi-
plexer at the beginning of each CE code pass. The RTM
can be enabled and disabled with control bit RTM_E. The
RTM output is clocked by CKTEST. Each RTM word is
clocked out in 35 CKCE cycles (1 CKCE cycle is equiva-
lent to 203ns) and contains a leading flag bit.
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Table 2. Inputs Selected in Multiplexer Cycles
Note: Only EQU = 5 is supported by currently available CE code versions for the 71M6545T/HT. Contact your Maxim Integrated rep-
resentative for CE codes that support equations 2, 3, and 4.
Pulse Generators
The 71M6545T/HT provides four pulse generators,
VPULSE, WPULSE, XPULSE and YPULSE, as well as
hardware support for the VPULSE and WPULSE pulse
generators. The pulse generators can be used to output
CE status indicators (for example, voltage sag) to DIO
pins. All pulses can be configured to generate interrupts
to the MPU.
The polarity of the pulses may be inverted with control bit
PLS_INV. When this bit is set, the pulses are active high,
rather than the more usual active low. PLS_INV inverts all
four pulse outputs.
The function of each pulse generator is determined by
the CE code and the MPU code must configure the cor-
responding pulse outputs in agreement with the CE code.
For example, standard CE code produces a mains zero-
crossing pulse on XPULSE and a SAG pulse on YPULSE.
A common use of the zero-crossing pulses is to gener-
ate interrupt in order to drive real-time clock software in
places where the mains frequency is sufficiently accurate
to do so and also to adjust for crystal aging. A common
use for the SAG pulse is to generate an interrupt that
alerts the MPU when mains power is about to fail, so that
the MPU code can store accumulated energy and other
data to EEPROM before the VV3P3SYS supply voltage
actually drops.
XPULSE and YPULSE
Pulses generated by the CE may be exported to the
XPULSE and YPULSE pulse output pins. Pins SEGDIO6
and SEGDIO7 are used for these pulses, respectively.
Generally, the XPULSE and YPULSE outputs can be
updated once on each pass of the CE code.
VPULSE and WPULSE
By default, WPULSE emits a pulse proportional to real
energy consumed, and VPULSE emits a pulse propor-
tional to reactive energy. During each CE code pass the
hardware stores exported WPULSE and VPULSE sign
bits in an 8-bit FIFO and sends the buffered sign bits to
the output pin at a specified, known interval. This permits
the CE code to calculate the VPULSE and WPULSE
outputs at the beginning of its code pass and to rely on
hardware to spread them over the multiplexer frame.
80515 MPU Core
The 71M6545T/HT includes an 80515 MPU (8-bit,
8051-compatible) that processes most instructions in
one clock cycle: a 4.9MHz clock results in a processing
throughput of 4.9 MIPS. The 80515 architecture eliminates
redundant bus states and im plements parallel execution
of fetch and execution phases. Normally, a machine cycle
is aligned with a memory fetch, there fore, most of the
1-byte instructions are performed in a single machine
cycle (MPU clock cycle). This leads to an 8x average per-
formance im prove ment (in terms of MIPS) over the 8051
device running at the same clock frequency.
The CKMPU frequency is a function of the MCK clock
(19.6608MHz) divided by the MPU clock divider which
is set in the I/O RAM control field MPU_DIV[2:0]. Actual
processor clocking speed can be adjusted to the total
pro cessing demand of the application (metering calcula-
tions, AMR management, memory management, and I/O
management) using MPU_DIV[2:0], as shown in Table 3.
Memory Organization and Addressing
The 80515 MPU core incorporates the Harvard archi-
tecture with separate code and data spaces. Memory
organization in the 80515 is similar to that of the industry
standard 8051. There are three memory areas: program
memory (flash, shared by MPU and CE), external RAM
(data RAM, shared by the CE and MPU, configuration or
I/O RAM), and internal data memory (internal RAM).
EQU DESCRIPTION Wh AND VARh FORMULA RECOMMENDED
MULTIPLEXER SEQUENCE
ELEMENT 0 ELEMENT 1 ELEMENT 2
2 2-element, 3W 3ph Delta VA x IA VA x IB N/A IA VA IB VB
3 2-element, 4W 3ph Delta VA (IA-IB)/2 VC x IC N/A IA VA IB VB IC VC
4 2-element, 4W 3ph Wye VA (IA-IB)/2 VB (IC-IB)/2 N/A IA VA IB VB IC VC
5 3-element, 4W 3ph Wye VA x IA VB x IA VC x IC IA VA IB VB IC VC (ID)
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Program Memory
The 80515 can address up to 64KB of program memory
space (0x0000 to 0xFFFF). Program memory is read
when the MPU fetches instructions or performs a MOVC
operation.
After reset, the MPU starts program execution from pro-
gram memory location 0x0000. The lower part of the pro-
gram memory includes reset and interrupt vectors. The
interrupt vectors are spaced at 8-byte in tervals, starting
from code space location 0x0003.
MPU External Data Memory (XRAM)
Both internal and external memory is physically located
on the 71M654xT device. The ex ternal mem ory referred
in this documentation is only external to the 80515 MPU
core.
3KB of RAM starting at address 0x0000 is shared by the
CE and MPU. The CE normally uses the first 1KB, leav-
ing 2KB for the MPU. Different versions of the CE code
use varying amounts. Consult the documentation for the
specific code version being used for the exact limit.
MOVX Addressing
There are two types of instructions differing in whether
they provide an 8-bit or 16-bit indirect address to the
external data RAM:
• MOVX A,@Ri: The contents of R0 or R1 in the current
register bank provide the eight low-order address bits
with the eight high-order bits specified by the PDATA
SFR. This method allows the user paged access (256
pages of 256 bytes each) to all ranges of the external
data RAM.
• MOVX A,@DPTR: The data pointer generates a 16-bit
address. This form is faster and more efficient when
accessing very large data arrays (up to 64KB) since no
additional instructions are needed to set up the eight
high ordered bits of the address.
It is possible to mix the two MOVX types. This provides
the user with four separate data pointers, two with direct
access and two with paged access, to the entire external
memory range.
Table 3. CKMPU Clock Frequencies
Table 4. Memory Map
MPU_DIV [2:0] CKMPU FREQUENCY
000 4.9152MHz
001 2.4576MHz
010 1.2288MHz
011 614.4kHz
100
307.2kHz
101
110
111
ADDRESS
(hex)
MEMORY
TECHNOLOGY
MEMORY
TYPE NAME TYPICAL USAGE MEMORY SIZE
(BYTES)
0000-FFFF
(64K) Flash Memory Nonvolatile Program memory for MPU and
CE
MPU program and
nonvolatile data 64K
CE program (on 1KB
boundary) 3K max
0000-0BFF Static RAM Volatile External RAM (XRAM) Shared by CE and MPU 5K
2000-27FF Static RAM Volatile CongurationRAM(I/ORAM) Hardware control 2K
2800-287F Static RAM Nonvolatile
(battery) CongurationRAM(I/ORAM) Battery-buffered memory 128
0000-00FF Static RAM Volatile Internal RAM Part of 80515 Core 256
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Dual Data Pointer
The Dual Data Pointer accelerates the block moves of
data. The standard DPTR is a 16-bit register that is used
to address external memory or peripherals. In the 80515
core, the standard data pointer is called DPTR, the sec-
ond data pointer is called DPTR1. The data pointer select
bit, located in the LSB of the DPS register, chooses the
active pointer. DPTR is selected when DPS[0] = 0 and
DPTR1 is selected when DPS[0] = 1.
The user switches between pointers by toggling the LSB
of the DPS register. The values in the data pointers are
not affected by the LSB of the DPS register. All DPTR
related instructions use the currently selected DPTR for
any activity.
An alternative data pointer is available in the form of the
PDATA register (SFR 0xBF), sometimes referred to as
USR2). It defines the high byte of a 16-bit address when
reading or writing XDATA with the instruction MOVX A,@
Ri or MOVX @Ri,A.
Internal Data Memory Map and Access
The Internal data memory provides 256 bytes (0x00 to
0xFF) of data memory. The internal data memory address
is always 1 byte wide.
The Special Function Registers (SFR) occupy the upper
128 bytes. The SFR area of internal data memory is
available only by direct addressing. Indirect address-
ing of this area accesses the upper 128 bytes of Internal
RAM. The lower 128 bytes contain working registers and
bit addressable memory. The lower 32 bytes form four
banks of eight registers (R0-R7). Two bits on the program
memory status word (PSW, SFR 0xD0) select which bank
is in use. The next 16 bytes form a block of bit address-
able memory space at addresses 0x00-0x7F. All of the
bytes in the lower 128 bytes are accessible through direct
or indirect addressing.
Special Function Registers
Only a few addresses in the SFR memory space are
occupied; other addresses are unim plemented. A read
access to unimplemented addresses returns undefined
data, while a write access has no effect. SFRs specific to
the 71M654xT are shown in bold print on a shaded field.
The registers at 0x80, 0x88, 0x90, etc., are bit address-
able, all others are byte addressable.
Timers and Counters
The 71M6545T/HT contains two 16-bit timer/counter
registers: Timer 0 and Timer 1. These registers can be
configured for counter or timer operations.
In timer mode, the register is incremented every machine
cycle, i.e., it counts up once for every 12 periods of the
MPU clock. In counter mode, the register is incremented
when the falling edge is observed at the corresponding
input signal T0 or T1 (T0 and T1 are the timer gating
inputs derived from certain DIO pins, see 2.5.8 Digital
I/O). Since it takes 2 machine cycles to recognize a
1-to-0 event, the maximum input count rate is 1/2 of the
clock frequency (CKMPU). There are no restrictions on
the duty cycle, how ever to ensure proper recognition of
the 0 or 1 state, an input should be stable for at least 1
machine cycle.
Four operating modes can be selected for Timer 0 and
Timer 1. The TMOD register is used to select the appro-
priate mode. The timer/counter operation is controlled by
the TCON register. Bits TR1 and TR0 in the TCON regis-
ter start their associated timers when set.
Table 5. Internal Data Memory Map
ADDRESS RANGE DIRECT ADDRESSING INDIRECT ADDRESSING
0x80 0xFF Special Function Registers (SFRs) RAM
0x30 0x7F Byte addressable area
0x20 0x2F Bit addressable area
0x00 0x1F Register banks R0…R7
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Table 6. Special Function Register Map
Table 7. Generic 80515 SFRs: Location and Reset Values
HEX/
BIN
BIT
ADDRESSABLE BYTE ADDRESSABLE BIN/
HEX
X000 X001 X010 X011 X100 X101 X110 X111
F8 INTBITS VSTAT RCMD SPI_CMD FF
F0 B F7
E8 IFLAGS EF
E0 A E7
D8 WDCON DF
D0 PSW D7
C8 T2CON CF
C0 IRCON C7
B8 IEN1 IP1 S0RELH S1RELH PDATA BF
B0 P3 (DIO12:15) FLSH_CTL FLSH_
PGADR B7
A8 IEN0 IP0 S0RELL AF
A0 P2 (DIO8:11) A7
98 S0CON S0BUF IEN2 S1CON S1BUF S1RELL EEDATA EECTRL 9F
90 P1(DIO4:7) DPS FLH_
ERASE 97
88 TCON TMOD TL0 TL1 TH0 TH1 CKCON 8F
80 P0 (DIO0:3) SP DPL DPH DPL1 DPH1 PCON 87
NAME ADDRESS RESET VALUE DESCRIPTION
P0 0x80 0xFF Port 0
SP 0x81 0x07 Stack Pointer
DPL 0x82 0x00 Data Pointer Low 0
DPH 0x83 0x00 Data Pointer High 0
DPL1 0x84 0x00 Data Pointer Low 1
DPH1 0x85 0x00 Data Pointer High 1
PCON 0x87 0x00 UART Speed Control
TCON 0x88 0x00 Timer/Counter Control
TMOD 0x89 0x00 Timer Mode Control
TL0 0x8A 0x00 Timer 0, low byte
TL1 0x8B 0x00 Timer 1, high byte
TH0 0x8C 0x00 Timer 0, low byte
TH1 0x8D 0x00 Timer 1, high byte
CKCON 0x8E 0x01 Clock Control (Stretch = 1)
P1 0x90 0xFF Port 1
DPS 0x92 0x00 Data Pointer select Register
S0CON 0x98 0x00 Serial Port 0, Control Register
S0BUF 0x99 0x00 Serial Port 0, Data Buffer
IEN2 0x9A 0x00 Interrupt Enable Register 2
S1CON 0x9B 0x00 Serial Port 1, Control Register
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Table 7. Generic 80515 SFRs - Location and Reset Values (continued)
Table 8. Timers/Counters Mode Description
Interrupts
The 80515 provides 11 interrupt sources with four priority
levels. Each source has its own interrupt request flag(s)
located in a special function register (TCON, IRCON, and
SCON). Each interrupt requested by the corresponding
interrupt flag can be individually enabled or disabled by
the interrupt enable bits in the IEN0, IEN1, and IEN2.
Referring to Figure 12, interrupt sources can origi-
nate from within the 80515 MPU core (referred to as
Internal Sources) or can originate from other parts of the
71M654xT SoC (referred to as External Sources). There
are seven external interrupt sources, (EX0-EX6).
Interrupt Overview
When an interrupt occurs, the MPU vectors to the prede-
termined address. Once the interrupt service has begun,
it can be interrupted only by a higher priority interrupt. The
interrupt service is terminated by a return from interrupt
instruction (RETI). When a RETI instruction is executed,
the processor returns to the instruction that would have
been next when the interrupt occurred.
When the interrupt condition occurs, the processor also
indicates this by setting a flag bit. This bit is set regardless
of whether the interrupt is enabled or disabled. Each inter-
rupt flag is sampled once per machine cycle, and then
S1BUF 0x9C 0x00 Serial Port 1, Data Buffer
NAME ADDRESS RESET VALUE DESCRIPTION
S1RELL 0x9D 0x00 Serial Port 1, Reload Register, low byte
P2 0xA0 0xFF Port 2
IEN0 0xA8 0x00 Interrupt Enable Register 0
IP0 0xA9 0x00 Interrupt Priority Register 0
S0RELL 0xAA 0xD9 Serial Port 0, Reload Register, low byte
P3 0xB0 0xFF Port 3
IEN1 0xB8 0x00 Interrupt Enable Register 1
IP1 0xB9 0x00 Interrupt Priority Register 1
S0RELH 0xBA 0x03 Serial Port 0, Reload Register, high byte
S1RELH 0xBB 0x03 Serial Port 1, Reload Register, high byte
PDATA 0xBF 0x00 High address byte for MOVX@Ri - also called USR2
IRCON 0xC0 0x00 Interrupt Request Control Register
T2CON 0xC8 0x00 Polarity for INT2 and INT3
PSW 0xD0 0x00 Program Status Word
WDCON 0xD8 0x00 Baud Rate Control Register (only WDCON[7] bit used)
A 0xE0 0x00 Accumulator
B 0xF0 0x00 B Register
M1 M0 MODE FUNCTION
0 0 Mode 0
13-bit Counter/Timer mode with 5 lower bits in the TL0 or TL1 register and the remaining 8 bits
in the TH0 or TH1 register (for Timer 0 and Timer 1, respectively). The 3 high order bits of TL0
and TL1 are held at zero.
0 1 Mode 1 16-bit Counter/Timer mode.
1 0 Mode 2 8-bit auto-reload Counter/Timer. The reload value is kept in TH0 or TH1, while TL0 or TL1 is
incremented every machine cycle. When TLxoverows,avaluefromTHx is copied to TLx.
1 1 Mode 3 If Timer 1 M1 and M0 bits are set to 1, Timer 1 stops.
If Timer 0 M1 and M0 bits are set to 1, Timer 0 acts as two independent 8-bit Timer/Counters.
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samples are polled by the hardware. If the sample indi-
cates a pending interrupt when the interrupt is enabled,
then the interrupt request flag is set. On the next instruc-
tion cycle, the interrupt is acknowledged by hardware
forcing an LCALL to the appropriate vector address, if the
following conditions are met:
• No interrupt of equal or higher priority is already in
progress.
• An instruction is currently being executed and is not
completed.
• The instruction in progress is not RETI or any write
access to the registers IEN0, IEN1, IEN2, IP0 or IP1.
The following SFR registers control the interrupt functions:
• The interrupt enable registers: IEN0, IEN1 and IEN2.
• The Timer/Counter control registers, TCON and
T2CON.
• The interrupt request register, IRCON.
• The interrupt priority registers: IP0 and IP1.
External MPU Interrupts
The seven external interrupts are the interrupts external
to the 80515 core, i.e., signals that originate in other
parts of the 71M654xT, for example the CE, DIO, RTC, or
EEPROM interface.
The polarity of interrupts 2 and 3 is programmable in
the MPU via the I3FR and I2FR bits in T2CON (SFR
0xC8). Interrupts 2 and 3 should be programmed for
falling sensitivity (I3FR = I2FR = 0). The generic 8051
MPU literature states that interrupts 4 through 6 are
defined as rising-edge sensitive. Thus, the hardware
signals attached to interrupts 5 and 6 are inverted to
achieve the edge polarity shown in Table 9.
External interrupt 0 and 1 can be mapped to pins on the
device using DIO resource maps.
On-Chip Resources
Flash Memory
The device includes 64KB of on-chip flash memory. The
flash memory primarily contains MPU and CE program
code. It also contains images of the CE RAM and I/O
RAM. On power-up, be fore enabling the CE, the MPU
copies these images to their respective locations.
Flash space allocated for the CE program is limited to
4096 16-bit words (8KB). The CE program must begin
on a 1KB boundary of the flash address space. The
CE_LCTN[5:0] field defines where in flash the CE code
resides. The address of the CE program is 0bXXXX XX00
0000 0000, where XXXX XX represents one of the 64
1KB pages at which the CE program begins.
Flash memory can be accessed by the MPU and the CE
for reading, and by the SPI interface for reading or writing.
MPU/CE RAM
The 71M6545T/HT includes 5KB of static RAM memory
on-chip (XRAM) plus 256 bytes of internal RAM in the
MPU core. The static RAM is used for data storage for
both MPU and CE operations.
I/O RAM
The I/O RAM can be seen as a series of hardware reg-
isters that control basic hardware functions. I/O RAM
address space starts at 0x2000.
The 71M6545T/HT includes 128 bytes NV RAM memory
on-chip in the I/O RAM address space (addresses 0x2800
to 0x287F). This memory section is supported by the volt-
age applied at VBAT_RTC and the data in it are preserved
in BRN, LCD, and SLP modes as long as the voltage at
VBAT_RTC is within specification.
Table 9. External MPU Interrupts
EXTERNAL
INTERRUPT CONNECTION POLARITY FLAG
RESET
0 Digital I/O (IE0) Programmable Automatic
1 Digital I/O (IE1) Programmable Automatic
2 CE_PULSE (IE_XPULSE, IE_YPULSE, IE_WPLUSE, IE_VPULSE) Rising Manual
3 CE_BUSY (IE3) Falling Automatic
4 VSTAT (VSTAT[2:0] changed) (IE4) Rising Automatic
5 EEPROM busy (falling), SPI (rising) (IE_EEX, IE_SPI) — Manual
6XFER_BUSY (falling), RTC_1SEC, RTC_1MIN, RTC_T, TC_TEMP
(IE_XFER, IE_RTC1S, IE_RTC1M, IE_RTCT) Falling Manual
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Crystal Oscillator
The oscillator drives a standard 32.768kHz tuning-fork
crystal. This type of crystal is accurate and does not
require a high-current oscillator circuit. The oscillator
power dissipation is very low to maximize the lifetime of
the VBAT_RTC battery.
Oscillator calibration can improve the accuracy of both the
RTC and metering.
PLL
Timing for the device is derived from the 32,768Hz
crystal oscillator. The oscillator output is routed to a
phase-locked loop (PLL). The PLL multiplies the crystal
frequency by 600 to produce a stable 19.6608MHz clock
frequency. This is the master clock (MCK), and all on-
chip timing, except for the RTC clock, is derived from
MCK.
The master clock can operate at either 19.66MHz or
6.29MHz depending on the PLL_FAST bit. The MPU
clock frequency CKMPU is determined by another divider
controlled by the I/O RAM control field MPU_DIV[2:0] and
can be set to MCK x 2-(MPU_DIV+2) , where MPU_DIV[2:0]
may vary from 0 to 4. The 71M654xT VV3P3SYS supply
current is reduced by reducing the MPU clock frequency.
When the ICE_E pin is high, the circuit also generates the
9.83MHz clock for use by the emulator.
The two general-purpose counter/timers contained in the
MPU are clocked by CKMPU.
The PLL is only turned off in SLP mode.
When the part is waking up from SLP mode, the PLL is
turned on in 6.29MHz mode, and the PLL frequency is not
be accurate until the PLL_OK flag becomes active. Due to
potential overshoot, the MPU should not change the value
of PLL_FAST until PLL_OK is true.
Real-Time Clock (RTC)
The real-time clock is driven directly by the crystal
oscillator and is powered by either the VV3P3SYS pin
or the VBAT_RTC pin, depending on the V3OK internal
bit. The RTC consists of a counter chain and a set of
output registers. The counter chain consists of registers
for seconds, minutes, hours, day of week, day of month,
month, and year. The chain registers are supported by a
shadow register that facilitates read and write operations.
RTC Trimming
The RTC accuracy can be trimmed by means of a digital
trimming mechanism that affects only the RTC. Either or
both of these adjustment mechanisms can be used to trim
the RTC.
The 71M6545T/HT can also be configured to regularly
measure die temperature, including in SLP mode and
while the MPU is halted. If enabled, the temperature infor-
mation is automatically used to correct for the tempera-
ture variation of the crystal. A quadratic equation is used
to compute the temperature correction factors.
The temperature is passed both to the quadratic calcula-
tion block and to a range check block. If the temperature
exceeds the limits established in the SMIN, SMAX and
SFILT registers when a range checking is enabled, a
WAKE or an INTERRUPT event is posted.
The quadratic calculation block computes the position on
the inverse parabolic curve that is characteristic for tuning
forkcrystalsbasedontheknownαandT0 values for the
crystal (these are published by the crystal manufacturer
and are relatively consistent for a particular crystal type).
Finally, the absolute frequency error is added or subtract-
ed from the computed value, and the final result is used
to compensate the frequency of the crystal.
RTC Interrupts
The RTC generates interrupts each second and each
minute. These interrupts are called RTC_1SEC and
RTC_1MIN. In addition, the RTC functions as an alarm
clock by generating an interrupt when the minutes and
hours registers both equal their respective target counts
as defined in the alarm registers. The alarm clock inter-
rupt is called RTC_T. All three interrupts appear in the
MPU’s external interrupt 6.
Temperature Sensor
The 71M654xT includes an on-chip temperature sensor
for determining the temperature of its bandgap re ference.
The primary use of the temperature data is to determine
the magnitude of compensation re quired to offset the ther-
mal drift in the system for the compensa tion of current,
voltage and energy measurement and the RTC. See the
Metrology Temperature Compensation.
The 71M654xT uses a dual-slope temperature measure-
ment technique that is operational in SLP mode, as well
as BRN and MSN modes. This means that the tempera-
ture sensor can be used to compensate for the frequency
variation of the crystal, even in SLP mode while the MPU
is halted.
In MSN and BRN modes, the temperature sensor is
awakened on command from the MPU by setting the
TEMP_START control bit. The MPU must wait for the
TEMP_START bit to clear before reading STEMP[15:0]
and before setting the TEMP_START bit once again.
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In SLP mode, it is awakened at a regular rate set by
TEMP_PER[2:0].
The result of the temperature measurement can be read
from STEMP[15:0]. Typically, only eleven bits are signifi-
cant, the remaining high-order bits reflecting the sign of
the temperature relative to 0C.
Battery Monitor
The 71M654xT temperature measurement circuit can
also monitor the batteries at the VBAT and VBAT_RTC
pins. The battery to be tested (i.e., VBAT or VBAT_RTC
pin) is selected by TEMP_BSEL.
When TEMP_BAT is set, a battery measurement is
performed as part of each temperature measurement.
The value of the battery reading is stored in register
BSENSE[7:0]. The battery voltage can be calculated by
using the formula in the BATTERY MONITOR section of
the electrical characteristics table.
In MSN mode, a 100µA de-passivation load can be applied
to the selected battery (i.e., selected by the TEMP_BSEL
bit) by setting the BCURR bit. Battery impedance can
be measured by taking a battery measurement with and
without BCURR. Regardless of the BCURR bit setting,
the battery load is never applied in BRN, LCD, and SLP
modes.
Digital I/O
On reset or power-up, all DIO pins are DIO inputs until
they are configured as desired under MPU control.
DIO pins can be configured independently as an input or
output. The PB pin is a dedicated digital input and is not
part of the DIO system.
Some pins (DIO2 through DIO11 and PB) can be routed
to internal logic such as the interrupt controller or a timer
channel. This routing is independent of the direction of the
pin, so that outputs can be configured to cause an inter-
rupt or start a timer.
A total of 32 combined DIO pins is available for the
71M6545T/HT. These pins can be categorized as follows:
18 DIO pins:
• DIO4…DIO5 (2 pins)
• DIO9…DIO14 (6 pins)
• DIO19…DIO25 (7 pins)
• DIO28…DIO29 (2 pins)
• DIO55 (1 pin)
9 DIO pins shared with other functions:
• DIO0/WPULSE, DIO1/VPULSE (2 pins)
• DIO2/SDCK, DIO3/SDATA (2 pins)
• DIO6/XPULSE, DIO7/YPULSE (2 pins)
• DIO8/DI (1 pin)
• DIO26, DIO27 (2 pins)
9 dedicated pins are available:
• SPI interface pins: SPI_CSZ, SPI_DO, SPI_DI, SPI_
CKI (4 pins)
• ICE Inteface pins: E_RXTX, E_TCLK, E_RST (3 pins)
• Test Port pins: TMUX2OUT, TMUXOUT (2 pins)
EEPROM Interface
The 71M654xT provides hardware support for both two-
pin (I2C) and three-wire (MICROWIRE) EEPROMs.
Two-Pin EEPROM Interface
The two-pin serial interface is multiplexed onto the DIO2
(SDCK) and DIO3 (SDATA) pins. Configure the interface
for two-pin mode by setting DIO_EEX[1:0] = 01. The
MPU communicates with the interface through the SFR
registers EEDATA and EECTRL. To write a byte of data
to the EEPROM the MPU places the data in EEDATA and
then writes the Transmit code to EECTRL. This initiates
the transmit operation which is finished when the BUSY
bit falls. INT5 is also asserted when BUSY falls. The MPU
can then check the RX_ACK bit to see if the EEPROM
acknowledged the trans mission.
A byte is read by writing the Receive command to
EECTRL and waiting for the BUSY bit to fall. Upon com-
pletion, the received data is in EEDATA. The serial trans-
mit and receive clock is 78kHz during each transmission,
and then holds in a high state until the next transmission.
The two-pin interface handles protocol details. The MPU
can command the interface to issue a start, a repeated
start and a stop condition, and it can manage the transmit-
ted ACK status as well.
Three-Wire EEPROM Interface
The three-wire interface supports standard MICROWIRE
(single data pin with clock and select pins) or a subset of
SPI (separate DI and DO pins with clock and select pins).
MICROWIRE is selected by setting DIO_EEX[1:0] = 10. In
this mode, EECTRL selects whether the interface is send-
ing or receiving, and eight bits of data are transferred in
each transaction. In this configuration, DIO2 is configured
for clock, and DIO3 is configured for data.
When separate DI/DO pins are selected (DIO_EEX[1:0]
= 11) the interface operates as a subset of SPI. Only SPI
modes 0 or 3 are supported. In this configuration, DIO3 is
DO and DIO8 is DI.
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UART
The 71M6545T/HT includes a UART (UART0) that can
be programmed to communicate with a variety of AMR
modules and other external devices.
SPI Slave Port
The SPI slave port communicates directly with the MPU
data bus and is able to read and write Data RAM and
I/O RAM locations. It is also able to send commands to
the MPU. The interface to the slave port consists of the
SPI_CSZ, SPI_CKI, SPI_DI and SPI_DO pins.
Additionally, the SPI interface allows flash memory to
be read and to be programmed. To facilitate flash pro-
gramming, cycling power or asserting RESET causes
the SPI port pins to default to SPI mode. The SPI port is
disabled by clearing the SPI_E bit.
Possible applications for the SPI interface are:
• An external host reads data from CE locations to
obtain metering information. This can be used in
applications where the 71M654xT function as a smart
front-end with preprocessing capability. Since the
addresses are in 16-bit format, any type of XRAM data
can be accessed: CE, MPU, I/O RAM, but not SFRs or
the 80515-internal register bank.
• A communication link can be established via the SPI
interface: By writing into MPU memory locations, the
external host can initiate and control processes in the
71M654xT MPU. Writing to a CE or MPU location
normally generates an interrupt, a function that can be
used to signal to the MPU that the byte that had just
been written by the external host must be read and
processed. Data can also be inserted by the external
host without generating an interrupt.
• An external DSP can access front-end data gener-
ated by the ADC. This mode of operation uses the
71M654xT as an analog front-end (AFE).
• Flash programming by the external host (SPI Flash
Mode).
SPI Safe Mode
Sometimes it is desirable to prevent the SPI interface
from writing to arbitrary RAM locations and thus disturb-
ing MPU and CE operation. This is especially true in AFE
applications. For this reason, the SPI SAFE mode was
created. In SPI SAFE mode, SPI write operations are
disabled except for a 16 byte transfer region at address
0x400 to 0x40F. If the SPI host needs to write to other
addresses, it must use the SPI_CMD register to request
the write operation from the MPU. SPI SAFE mode is
enabled by the SPI_SAFE bit.
SPI Flash Mode (SFM)
In normal operation, the SPI slave interface cannot read
or write the flash memory. However, the 71M6545T/HT
supports an SPI Flash Mode (SFM) which facilitates initial
programming of the flash memory. When in SFM mode,
the SPI can erase, read, and write the flash memory.
Other memory elements such as XRAM and I/O RAM are
not accessible in this mode. In order to protect the flash
contents, several operations are required before the SFM
mode is successfully invoked.
In SFM mode, n byte reads and dual-byte writes to flash
memory are supported. Since the flash write operation is
always based on a two-byte word, the initial address must
always be even. Data is written to the 16-bit flash memory
bus after the odd word is written.
In SFM mode, the MPU is completely halted. The
71M6545T/HT must be reset by the WD timer or by the
RESET pin in order to exit SFM mode.
If the SPI port is used for code updates (in lieu of a
programmer that uses the ICE port), then a code that
disables the flash access through SPI can potentially lock
out flash program updates.
Hardware Watchdog Timer
An independent, robust, fixed-duration, watchdog timer
(WDT) is included in the 71M6545T/HT. It uses the RTC
crystal oscillator as its time base and must be refreshed
by the MPU firmware at least every 1.5 seconds. When
not re freshed on time, the WDT overflows and the part is
reset as if the RESET pin were pulled high, except that
the I/O RAM bits are in the same state as after a wake-up
from SLP or LCD modes. After 4100 CK32 cycles (or 125
ms) following the WDT overflow, the MPU is launched
from program address 0x0000.
The watchdog timer is also reset when the internal signal
WAKE = 0.
Test Ports
Two independent multiplexers allow the selection of
internal analog and digital signals for the TMUXOUT and
TMUX2OUT pins (Table 10).
The TMUXOUT and TMUX2OUT pins may be used for
diagnostics purposes during the product development
cycle or in the production test. The RTC 1-second output
may be used to calibrate the crystal oscillator. The RTC
4-second output provides higher precision for RTC cali-
bration. RTCLK may also be used to calibrate the RTC.
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Table 10. Test Ports
TMUX[5:0] SIGNAL NAME DESCRIPTION
1 RTCLK 32.768 kHz clock waveform
9 WD_RST Indicates when the MPU has reset the watchdog timer. Can be monitored to determine
spare time in the watchdog timer.
A CKMPU MPU clock
D V3AOK bit
IndicatesthattheV3P3Apinvoltageis≥3.0V.TheV3P3AandV3P3SYSpinsare
expected to be tied together at the PCB level. The 71M6543 monitors the V3P3A pin
voltage only.
E V3OK bit
IndicatesthattheV3P3Apinvoltageis≥2.8V.TheV3P3AandV3P3SYSpinsare
expected to be tied together at the PCB level. The 71M654 monitors the V3P3A pin
voltage only.
1B MUX_SYNC Internal multiplexer frame SYNC signal.
1C CE_BUSY interrupt
1D CE_XFER interrupt
1F RTM output from CE
Note: All TMUX[5:0] values that are not shown are reserved.
TMUX2[4:0] SIGNAL NAME DESCRIPTION
0 WD_OVF Indicateswhenthewatchdogtimerhasexpired(overowed).
1 PULSE_1S
One-second pulse with 25% duty cycle. This signal can be used to measure the
deviation of the RTC from an ideal 1-second interval. Multiple cycles should be
averagedtogethertolteroutjitter.
2 PULSE_4S
Four-second pulse with 25% duty cycle. This signal can be used to measure the
deviation of the RTC from an ideal 4-second interval. Multiple cycles should be
averagedtogethertolteroutjitter.Thispulseprovidesamoreprecisemeasurement
than the 1-second pulse.
3 RTCLK 32.768 kHz clock waveform
8SPARE[1] bit – I/O
RAM 0x2704[1] Copies the value of the bit stored in 0x2704[1]. For general purpose use.
9SPARE[2] bit – I/O
RAM 0x2704[2] Copies the value of the bit stored in 0x2704[2]. For general purpose use.
A WAKE Indicates when a WAKE event has occurred.
B MUX_SYNC Internal multiplexer frame SYNC signal.
C MCK
E GNDD Digital GND. Use this signal to make the TMUX2OUT pin static.
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TMUX[5:0] SIGNAL NAME DESCRIPTION
1 RTCLK 32.768 kHz clock waveform
12 INT0 – DIG I/O
Interrupts
13 INT1 – DIG I/O
14 INT2 – CE_PULSE
15 INT3 – CE_BUSY
16 INT4 - VSTAT
17 INT5 – EEPROM/SPI
18 INT6 – XFER, RTC
1F RTM_CK(ash)
Note: All TMUX2[4:0] values which are not shown are reserved.
Table 10. Test Ports (continued)
Functional Description
Theory of Operation
The energy delivered by a power source into a load can
be expressed as:
t
0
E V(t)I(t)dt=∫
Assuming phase angles are constant, the following for-
mulae apply:
• P=RealEnergy[Wh]=VxAxcos(φ)xt
• Q=ReactiveEnergy[VARh]=VxAxsin(φ)xt
• S = Apparent Energy [VAh] =
22
PQ
+
For a practical meter, not only voltage and current ampli-
tudes, but also phase angles and harmonic content may
change constantly. Thus, simple RMS measurements are
inherently inaccurate. The 71M654xT, however, functions
by emulating the integral operation above by processing
current and voltage samples at a constant rate. As long
as the ADC resolution is high enough and the sample fre-
quency is beyond the harmonic range of interest, the cur-
rent and voltage samples, multiplied by the sample period
yield an accurate value for the instantaneous energy.
Summing the instantaneous energy quantities over time
provides accurate results for accumulated energy.
The application of 240V AC and 100A results in an accu-
mulation of 480Ws (= 0.133 Wh) over the 20ms period, as
indicated by the accumulated power curve. The described
sampling method works reliably, even in the presence of
dynamic phase shift and harmonic distortion.
Battery Modes
The 71M654xT can operate in one of three power modes:
mission (MSN), brownout (BRN), or sleep (SLP).
Shortly after system power (VV3P3SYS) is applied, the
part is in mission mode. MSN mode means that the part
is operating with system power and that the internal PLL
is stable. This mode is the normal operating mode where
the part is capable of measuring energy.
When system power is not available, the 71M654xT is in
one of three battery modes: BRN or SLP.
An internal comparator monitors the voltage at the
VV3P3A pin (note that VV3P3SYS and VV3P3A are typically
connected together at the PCB level). When the VV3P3A
DC voltage drops below 2.8 VDC, the comparator resets
an internal power status bit called V3OK. As soon as
system power is removed and V3OK = 0, the 71M654xT
switches to battery power (VBAT pin), notifies the MPU by
issuing an interrupt and updates the VSTAT[2:0] register.
The MPU continues to execute code when the system
transitions from MSN to BRN mode. Depending on the
MPU code, the MPU can choose to stay in BRN mode,
or transition to SLP mode. BRN mode is similar to MSN
mode except that resources powered by VV3P3A power,
such as the ADC are inaccurate. In BRN mode the CE
continues to run and should be turned off to conserve
VBAT power. Also, the PLL continues to function at the
same frequency as in MSN mode and its frequency
should be reduced to save power.
When system power is restored, the 71M654xT
automatically transitions from any of the battery modes
(BRN, LCD, SLP) back to MSN mode, switches back
to using system power (VV3P3SYS, VV3P3A), issues an
interrupt and updates VSTAT[1:0]. The MPU software
should restore MSN mode operation by issuing a soft
reset to restore system settings to values appropriate for
MSN mode.
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Figure 6. Waveforms Comparing Voltage, Current, Energy per Interval, and Accumulated Energy
Transitions from SLP mode to BRN mode can be initiated
by the following events:
1) Wake-up timer timeout.
2) Pushbutton (PB) is activated.
3) A rising edge on DIO4 or DIO55.
4) Activity on the RX or OPT_RX pins.
Brownout Mode
In BRN mode, most nonmetering digital functions are
active including ICE, UART, EEPROM, and RTC. In BRN
mode, the PLL continues to function at the same fre-
quency as MSN mode. It is up to the MPU to reduce the
PLL frequency or the MPU frequency in order to minimize
power consumption.
From BRN mode, the MPU can choose to enter SLP mode.
When system power is re stored while the 71M654xT is in
BRN mode, the part automatically transitions to MSN
mode.
Sleep Mode
When the VV3P3SYS pin voltage drops below 2.8 VDC,
the 71M654xT enters BRN mode and the VV3P3D pin
obtains power from the VBAT pin instead of the VV3P3SYS
pin. Once in BRN mode, the MPU may invoke SLP mode
by setting the SLEEP bit. The purpose of SLP mode is to
consume the least amount power while still maintaining
the real time clock, temperature compensation of the
RTC, and the nonvolatile portions of the I/O RAM.
In SLP mode, the VV3P3D pin is disconnected, removing
all sources of current leakage from the VBAT pin. The
nonvolatile I/O RAM locations and the SLP mode functions,
such as the temperature sensor, oscillator, RTC, and the
RTC temperature compensation are powered by the
VBAT_RTC pin. SLP mode can be exited only by a system
power-up event or one of the wake methods.
If the SLEEP bit is asserted when VV3P3SYS pin power is
present (i.e., while in MSN mode), the 71M654xT enters
SLP mode, resetting the internal WAKE signal, at which
point the 71M654xT begins the standard wake from sleep
procedures.
When power is restored to the VV3P3SYS pin, the
71M654xT transitions from SLP mode to MSN mode and
the MPU PC (Program Counter) is initialized to 0x0000.
At this point, the XRAM is in an undefined state, but
nonvolatile I/O RAM locations are preserved.
Applications Information
Connecting 5V Devices
All digital input pins of the 71M654xT are compatible with
external 5V devices. I/O pins configured as inputs do not
require current-limiting resistors when they are connected
to external 5V devices.
Direct Connection of Sensors
The 71M654xT supports direct connection of current
transformer and shunt-fed sensors.
Using the 71M6545T/HT with Local Sensors
The 71M6545T/HT can be configured to operate with
locally connected current sensors. All current inputs are
connected to a current transformer (CT) and are there-
fore isolated. This configuration implements a polyphase
-500
-400
-300
-200
-100
0
100
200
300
400
500
0510 15 20
TIME (ms)
V(V), I(A), P(Ws)
VOLTAGE (V)
CURRENT (A)
ENERGY PER INTERVAL (Ws)
ACCUMULATED ENERGY (Ws)
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measurement with tamper-detection using one current
sensor to measure the neutral current. For best perfor-
mance, all current sensor inputs are configured for dif-
ferential mode.
Using the 71M6545T/HT with Remote Sensors
The 71M6545T/HT can be configured to operate with
71M6x03 remote sensor interfaces and current shunts.
This configuration implements a polyphase measure-
ment with tamper-detection. For best performance, the
IADC0-IADC1 current sensor input is configured for differ-
ential mode (DIFFA_E = 1). The outputs of the 71M6x03
isolated sensor interface are routed through a pulse
transformer, which is connected to the current input pins
(IADC2-IADC7). The current input pins (IADC2-IADC7)
must be configured for remote sensor communication
(i.e., RMT_E =1).
Metrology Temperature Compensation
Since the VREF bandgap amplifier is chopper-stabilized
the DC offset voltage (the most significant long-term
drift mechanism in bandgap voltage references) is
automatically removed by the chopper circuit. Both the
71M654xT and the 71M6x03 feature chopper circuits
for their respective VREF voltage reference. VREF is
trimmed to a target value of 1.195V during the device
manufacturing process and the result of the trim stored in
nonvolatile fuses.
For the 71M654xT device (Q0.5% energy accuracy),
the TRIMT[7:0] value can be read by the MPU during
initialization in order to calculate parabolic temperature
compensation coefficients suitable for each individual
71M654xT device. The resulting temperature coefficient
for VREF in the 71M654xT is ±40 ppm/°C.
By using the trim information in the TRIMT register and
the sensed temperature, a gain adjustment for the sensor
can be computed. See the 71M6545T/HT User’s Guide
for more information about compensating sensors for
temperature variations.
Connecting I2C EEPROMs
I2C EEPROMs or other I2C compatible devices should be
connected to the DIO pins DIO2 and DIO3.
Pullup resistors of roughly 10kΩ to VV3P3D (to ensure
operation in BRN mode) should be used for both SDCK
and SDATA signals. The DIO_EEX[1:0] field in I/O RAM
must be set to 01 in order to convert the DIO pins DIO2
and DIO3 to I2C pins SDCK and SDATA.
Connecting Three-Wire EEPROMs
MICROWIRE EEPROMs and other compatible devices
should be connected to the DIO pins DIO2/SDCK and
DIO3/SDATA.
UART
The UART0 RX pin should be pulled down by a 10kΩ
resistor and additionally protected by a 100pF ceramic
capacitor.
With modulation, an optical emitter can be operated at
higher current than nominal, enabling it to increase the
distance along the optical path.
If operation in BRN mode is desired, the external
components should be connected to VV3P3D. However, it
is recommended to limit the current to a few mA.
Reset
Even though a functional meter does not necessarily
need a reset switch, it is useful to have a reset push-
button for prototyping. The RESET signal may be sourced
from VV3P3SYS (functional in MSN mode only), VV3P3D
(MSN and BRN modes), or VBAT (all modes, if a battery
is present), or from a combination of these sources,
depending on the application. RESET causes the CPU to
restart and returns all IO RAM values to their default values.
For a production meter, the RESET pin should be protect-
ed by the external components. R1 should be in the range
of100ΩandmountedascloselyaspossibletotheIC.
Emulator Port Pins
Even when the emulator is not used, small shunt capaci-
tors to ground (22pF) should be used for protection from
EMI. Production boards should have the ICE_E pin con-
nected to ground.
MPU Firmware Library
All application-specific MPU functions are featured in the
demonstration C source code supplied by Maxim Integrated.
The code is available as part of the Demonstration Kit for
the 71M6545T/HT. The Demonstration Kits come with pre-
programmed with demo firmware and mounted on a func-
tional sample meter Demo Board. The Demo Boards allow
for quick and efficient evaluation of the IC without having
to write firmware or having to supply an in-circuit emulator
(ICE). Contact Maxim Integrated for information on price and
availability of demonstration boards.
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Figure 7. Typical Voltage Sense Circuit Using Resistive Divider
Figure 8. Typical Current-Sense Circuit Using Current Transformer in a Single-Ended Configuration
Figure 9. Typical Current-Sense Circuit Using Current Transformer in a Differential Configuration
Figure 10. Typical Current-Sense Circuit Using Shunt in a Differential Configuration
R
IN
V
IN
VA
V3P3
A
R
OUT
VOUT
IOUT
IAP
V3P3
A
CT
1:N
IIN
RBURDEN
NOISE FILTER
IOUT
IAP
IAN
V3P3A
CT
1:N
IIN
VOUT
RBURDEN
BIAS NETWORK AND NOISE FILTER
IIN
IAP
IAN
V3P3A
VOUT
RSHUNT
BIAS NETWORK AND NOISE FILTER
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Figure 11. 71M6545T/HT Typical Operating Circuit Using Locally Connected Sensors
MPU
RTC
TIMERS
IADC0
IADC2
IADC3
VADC9 (VB)
IADC4
IADC5
VADC10 (VC)
IADC6
IADC7
XIN
DIO
VV3P3D
24
XOUT
TX
RX
VV3P3A VV3P3SYS
*IN = OPTIONAL NEUTRAL CURRENT
PB
VBAT_RTC
GNDA GNDD
TMUX COMPUTE
ENGINE
NEUTRAL
CURRENT TRANSFORMERS
LOAD
PHASE A
PHASE B
PHASE
C
AMR
ICE
SERIAL PORTS
OSCILLATOR/PLL
MUX AND ADC
DIO, PULSES,
LEDs
RAM
32kHz
DIO
REGULATOR
POWER SUPPLY
71M6545T
71M6545HT
TEMPERATURE
SENSOR
VREF
RTC
BATTERY
PWR MODE
CONTROL
IADC1
VADC8 (VA)
IA
IB
IC
IN* BATTERY
MONITOR
SPI INTERFACE
HOST
SPI_CKI
SPI_DI
SPI_DO
SPI_CSZ
XFER_BUSY
SAG
RESISTOR DIVIDERS
NEUTRAL
NOTE: THIS SYSTEM IS REFERENCED TO NEUTRAL
I2C OR µWIRE
EEPROM
3.3VDC
PULSES
WPULSE
XPULSE
RPULSE
YPULSE
FLASH
MEMORY
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Figure 12. 71M6545T/HT Typical Operating Circuit Using Remote Neutral Current Sensor
VV3P3A VV3P3SYS
VBAT_RTC
GNDA GNDD
RAM
REGULATOR
POWER SUPPLY
71M6545T
71M6545HT
TEMPERATURE
SENSOR
VREF
PWR MODE
CONTROL
BATTERY
MONITOR
IADC0
VADC9 (VB)
IADC4
IADC5
VADC8 (VA)
IADC2
IADC3
NEUTRAL
SHUNT CURRENT SENSORS
LOAD
C
B
A
MUX AND ADC
IADC1
VADC10 (VC)
IADC6
IADC7
IN*
IC
IB
IA
RESISTOR DIVIDERS
NOTE: THIS SYSTEM IS
REFERENCED TO NEUTRAL
PULSE TRANSFORMERS
NEUTRAL
71M6xx3
*IN = OPTIONAL NEUTRAL CURRENT
PB
AMR
FLASH
MEMORY
ICE
TX
RX
SERIAL PORTS
TMUX COMPUTE
ENGINE
MPU
RTC
TIMERS
RAM
SPI INTERFACE
RTC
BATTERY
XIN
DIO
VV3P3D
24
XOUT
OSCILLATOR/PLL
DIO, PULSES,
LEDs
32kHz
DIO
I2C OR µWIRE
EEPROM
3.3VDC
PULSES
WPULSE
XPULSE
RPULSE
YPULSE
HOST
SPI_CKI
SPI_DI
SPI_DO
SPI_CSZ
XFER_BUSY
SAG
71M6xx3 71M6xx3
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Figure 13. Typical I2C Operating Circuit
Figure 14. Typical UART Operating Circuit
Figure 15. Typical Reset Circuits
Figure 16. Typical Emulator Connections
10kΩ
V3P3D
SDCK
EEPROM
71M654xT
SEGDIO2/SDCK
10kΩ
SDATASEGDIO3/SDATA
10kΩ
RX
71M654xT
RX
100pF
TXTX
62Ω
71M654xT
E_RST
22pF 22pF 22pF
62Ω
E_RXT
62Ω
E_TCLK
ICE_E
V3P3D
R1
10kΩ
R2
1kΩ
71M654xT
V3P3D
VBAT/
V3P3D
RESET
SWITCH
0.1µF
RESET
GNDD
R1
100Ω
RESET
GNDD
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Meter Calibration
Once the 71M654xT energy meter device has been
installed in a meter system, it must be calibrated. A com-
plete calibration includes:
• Establishment of the reference temperature (typically
22°C).
• Calibration of the metrology section: calibration for toler-
ances of the current sensors, voltage dividers and sig-
nal conditioning components as well as of the internal
reference voltage (VREF) at the reference temperature.
The metrology section can be calibrated using the gain
and phase adjustment factors accessible to the CE. The
gain adjust ment is used to compensate for tolerances of
components used for signal conditioning, especially the
resistive components. Phase adjustment is provided to
compensate for phase shifts introduced by the current
sensors or by the effects of reactive power supplies.
Due to the flexibility of the MPU firmware, any calibration
method, such as calibration based on energy, or current
and voltage can be implemented. It is also possible to
implement segment-wise calibration (depending on cur-
rent range).
The 71M6545T/HT support common industry standard
calibration techniques, such as single-point (energy-only),
multipoint (energy, VRMS, IRMS), and auto-calibration.
Contact Maxim Integrated to obtain a copy of the latest
calibration spreadsheet file for the 71M654xT.
Firmware Interface
Overview: Functional Order
The I/O RAM locations at addresses 0x2000 to 0x20FF
have sequential addresses to facilitate reading by the
MPU. These I/O RAM locations are usually modified only
at power-up. These addresses are an alternative sequen-
tial address to subsequent addresses (above 0x2100).
For instance, EQU[2:0] can be accessed at I/O RAM
0x2000[7:5] or at I/O RAM 0x2106[7:5].
Unimplemented (U) and reserved (R) bits are shaded in
light gray. Unimplemented bits are identified with a ‘U’.
Unimplemented bits have no memory storage, writing
them has no effect, and reading them always returns zero.
Reserved bits are identified with an ‘R’, and must always
be written with a zero. Writing values other than zero to
reserved bits may have undesirable side effects and must
be avoided.
Nonvolatile bits are shaded in dark gray. Nonvolatile bits
are backed up during power failures if the system includes
a battery connected to the VBAT pin.
I/O RAM Map: Details
Writable bits are written by the MPU into configuration
RAM. Typically, they are initially stored in flash memory
and copied to the configuration RAM by the MPU. Some
of the more frequently programmed bits are mapped to
the MPU SFR memory space. The remaining bits are
mapped to the address space 0x2XXX. The RST and WK
columns describe the bit values upon reset and wake,
respectively. No entry in one of these columns means the
bit is either read-only or is powered by the NV supply and
is not initialized. Write-only bits return zero when they are
read.
Locations that are shaded in grey are nonvolatile (i.e.,
battery-backed).
Reading the Info Page
Information useful for calibrating the temperature sensor
and other functions is available in trim fuses. The trim
fuse values provided in the 71M654xT devices cannot
be directly accessed through the I/O RAM space. They
reside in a special area termed the Info Page. The MPU
gains access to the Info Page by setting the INFO_PG
(I/O RAM 0x270B[0]) control bit. Once this bit is set, Info
Page contents are accessible in program memory space
starting at the address specified by the contents of CE_
LCTN[6:0] (71M654xGT) or CE_LCTN[5:0] (71M654xFT)
(I/O RAM 0x2109[6:0] for 71M654xGT or 0x2109[5:0] for
71M654xFT). These pointers specify a base address at a
1KB address boundary which is at 1024 x CE_LCTN[6:0]
(71M654xGT) or CE_LCTN[5:0] (71M654xFT). Table 11
provides a list of the available trim fuses and their corre-
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sponding offsets relative to the Info Page base address.
After reading the desired Info Page information, the MPU
must reset the INFO_PG bit. The code below provides
an example for reading Info Page fuse trims. In this
code example, the address, px is a pointer to the MPU’s
code space. In assembly language, the Info Page data
objects, which are read-only, must be accessed with the
MOVC 8051 instruction. In the C-language, Info Page
trim fuses must be fetched with a pointer of the correct
width, depending on the format of the trim fuse (an 8-bit
or a 16-bit data object). The case statements in the code
example below perform casts to obtain a pointer of the
correct size for each object, as needed.
In assembly language, the MPU has to form 11-bit or
16-bit values from two separate 8-bit fetches, depending
on the object being fetched. The byte values containing
less than 8 valid bits are LSB justified. For example Info
Page offset 0x90 is an 8-bit object whose three LSBs are
bits [10:8] of the complete TEMP_85[10:0] 11-bit object.
The Info Page data objects are 2s complement format
and should be sign-extended when read into a 16-bit data
type (see case _TEMP85 in the code example).
#if HIGH_PRECISION_METER
int16_t read_trim (enum eTRIMSEL
select) {
uint8r_t *px;
int16_t x;
px = ((uint16_t)select) +
((uint8r_t *)(CE3 << 10));
switch (select)
{
default:
case _TRIMBGD:
INFO_PG = 1;
x = *px;
INFO_PG = 0;
break;
case _TRIMBGB:
INFO_PG = 1;
x = *(uint16r_t*)px;
INFO_PG = 0;
break;
case _TEMP85:
INFO_PG = 1;
x = *(uint16r_t*)px;
INFO_PG = 0;
if (x & 0x800) x |= 0xF800;
break;
}
return (x); }
#endif //#if HIGH_PRECISION_METER
Table 11. Info Page Trim Fuses
REGISTER NAME DEFINITION LOCATION ADDRESS FORMAT TYPICAL VALUE
STEMP_T85_P STEMP at +85C Info Block 0xAA, 0xAB 16 bits, signed 4400
STEMP_T22_P STEMP at +22C Info Block 0x8A, 0x8B 13 bits, unsigned 3600
T85_P Probe temperature at +85C Info Block 0xA6, 0xA7 16 bits signed 605
T22_P Probe temperature at +22C Info Block 0x9A 8 bits signed 35
STEMP Temperature sensor I/O RAM 0x2882,
0x2882 11 bits, sign extended
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Table 12. I/O RAM Locations in Numerical Order
NAME ADDR BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
CE6 2000 EQU[2:0] U CHOP_E[1:0] RTM_E CE_E
CE5 2001 U U U SUM_SAMPS[12:8]
CE4 2002 SUM_SAMPS[7:0]
CE3 2003 U U CE_LCTN[5:0]
CE2 2004 PLS_MAXWIDTH[7:0]
CE1 2005 PLS_INTERVAL[7:0]
CE0 2006 DIFF6_E DIFF4_E DIFF2_E DIFF0_E RFLY_DIS FIR_LEN[1:0] PLS_INV
RCE0 2007 CHOPR[1:0] RMT6_E RMT4_E RMT2_E R R R
RTMUX 2008 U TMUXRB[2:0] U TMUXRA[2:0]
Reserved 2009 U U R U U U U U
MUX5 200A MUX_DIV[3:0] MUX10_SEL
MUX4 200B MUX9_SEL MUX8_SEL
MUX3 200C MUX7_SEL MUX6_SEL
MUX2 200D MUX5_SEL MUX4_SEL
MUX1 200E MUX3_SEL MUX2_SEL
MUX0 200F MUX1_SEL MUX0_SEL
TEMP 2010 TEMP_BSEL TEMP_PWR OSC_COMP TEMP_BAT U TEMP_PER[2:0]
DIO_R5 201B U U U U U DIO_RPB[2:0]
DIO_R4 201C U DIO_R11[2:0] U DIO_R10[2:0]
DIO_R3 201D U DIO_R9[2:0] U DIO_R8[2:0]
DIO_R2 201E U DIO_R7[2:0] U DIO_R6[2:0]
DIO_R1 201F U DIO_R5[2:0] U DIO_R4[2:0]
DIO_R0 2020 U DIO_R3[2:0] U DIO_R2[2:0]
DIO0 2021 DIO_EEX[1:0] U U OPT_TXE[1:0] OPT_TXMOD OPT_TXINV
DIO1 2022 DIO_PW DIO_PV OPT_FDC[1:0] U OPT_RXDIS OPT_RXINV OPT_BB
DIO2 2023 DIO_PX DIO_PY U U U U U U
INT1_E 2024 EX_EEX EX_XPULSE EX_YPULSE EX_RTCT EX_TCTEMP EX_RTC1M EX_RTC1S EX_XFER
INT2_E 2025 EX_SPI EX_WPULSE EX_VPULSE
WAKE_E 2026 U EW_TEMP U EW_RX EW_PB EW_DIO4 U EW_DIO55
SFMM 2080 SFMM[7:0] (via SPI slave port only)
SFMS 2081 SFMS[7:0] (via SPI slave port only)
CE AND ADC
MUX5 2100 MUX_DIV[3:0] MUX10_SEL[3:0]
MUX4 2101 MUX9_SEL[3:0] MUX8_SEL[3:0]
MUX3 2102 MUX7_SEL[3:0] MUX6_SEL[3:0]
MUX2 2103 MUX5_SEL[3:0] MUX4_SEL[3:0]
MUX1 2104 MUX3_SEL[3:0] MUX2_SEL[3:0]
MUX0 2105 MUX1_SEL[3:0] MUX0_SEL[3:0]
CE6 2106 EQU[2:0] U CHOP_E[1:0] RTM_E CE_E
CE5 2107 U U U SUM_SAMPS[12:8]
CE4 2108 SUM_SAMPS[7:0]
CE3 2109 U U CE_LCTN[5:0]
CE2 210A PLS_MAXWIDTH[7:0]
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Table 12. I/O RAM Locations in Numerical Order (continued)
NAME ADDR BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
CE1 210B PLS_INTERVAL[7:0]
CE0 210C R R DIFFB_E DIFFA_E RFLY_DIS FIR_LEN[1:0] PLS_INV CE0
RTM0 210D U U U U U U RTM0[9:8]
RTM0 210E RTM0[7:0]
RTM1 210F RTM1[7:0]
RTM2 2110 RTM2[7:0]
RTM3 2111 RTM3[7:0]
FIR_EXT 2112 U U U U SLOT_EXT[3:0]
CLOCK GENERATION
CKGN 2200 OUT_SQ[1:0] ADC_DIV PLL_FAST RESET MPU_DIV[2:0]
VREF TRIM FUSES
TRIMT 2309 TRIMT[7:0]
DIO
DIO_R5 2450 U U U U U DIO_RPB[2:0]
DIO_R4 2451 U DIO_R11[2:0] U DIO_R10[2:0]
DIO_R3 2452 U DIO_R9[2:0] U DIO_R8[2:0]
DIO_R2 2453 U DIO_R7[2:0] U DIO_R6[2:0]
DIO_R1 2454 U DIO_R5[2:0] U DIO_R4[2:0]
DIO_R0 2455 U DIO_R3[2:0] U DIO_R2[2:0]
DIO0 2456 DIO_EEX[1:0] U UMUX_SEL OPT_TXE[1:0] OPT_TXMOD OPT_TXINV
DIO1 2457 DIO_PW DIO_PV OPT_FDC[1:0] U OPT_RXDIS OPT_RXINV OPT_TXINV
DIO2 2458 DIO_PX DIO_PY U OUT_SQE U U U U
NONVOLATILE BITS
TMUX 2502 U U TMUX[5:0]
TMUX2 2503 U U U TMUX2[4:0]
TC_A1 2508 U U U U U U TC_A[9:8]
TC_A2 2509 TC_A[7:0]
TC_B1 250A U U U U TC_B[11:8]
TC_B2 250B TC_B[7:0]
PQMASK 2511 U U U U U PQMASK[2:0]
TSEL 2518 U U U TEMP_SELE TEMP_SEL[3:0]
TSBASE1 2519 U U U U U SBASE[10:8]
TSBASE2 251A SBASE[7:0]
TSMAX 251B U SMAX[6:0]
TSMIN 251C U SMIN[6:0]
TSFILT 251D U U U U SFILT[3:0]
71M6x03 REMOTE INTERFACE
REMOTE2 2602 RMT_RD[15:8]
REMOTE1 2603 RMT_RD[7:0]
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Table 12. I/O RAM Locations in Numerical Order (continued)
NAME ADDR BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
RBITS
INT1_E 2700 EX_EEX EX_XPULSE EX_YPULSE EX_RTCT EX_TCTEMP EX_RTC1M EX_RTC1S EX_XFER
INT2_E 2701 EX_SPI EX_WPULSE EX_VPULSE U U U U U
SECURE 2702 FLSH_UNLOCK[3:0] R FLSH_RDE FLSH_WRE R
Analog0 2704 VREF_CAL VREF_DIS PRE_E ADC_E BCURR SPARE[2:0]
INTBITS 2707 U INT6 INT5 INT4 INT3 INT2 INT1 INT0
FLAG0 SFR E8 IE_EEX IE_XPULSE IE_YPULSE IE_RTCT IE_TCTEMP IE_RTC1M IE_RTC1S IE_XFER
FLAG1 SFR F8 IE_SPI IE_WPULSE IE_VPULSE U U U U PB_STATE
STAT SFR F9 U U U PLL_OK U VSTAT[2:0]
REMOTE0 SFR FC U PERR_RD PERR_WR RCMD[4:0]
SPI1 SFR FD SPI_CMD[7:0]
SPI0 2708 SPI_STAT[7:0]
RCE0 2709 CHOPR[1:0] R R RMT_E R R R
RTMUX 270A U R R R U TMUXRA[2:0]
INFO_PG 270B U U U U U U U INFO_PG
DIO3 270C U U PORT_E SPI_E SPI_SAFE U U U
TNM1 2710 U TEMP_NMAX[14:8]
TNM2 2711 TEMP_NMAX[7:0]
TM1 2712 U U U U TEMP_M[11:8]
TM2 2713 TEMP_M[7:0]
TNB1 2714 TEMP_NBAT[15:8]
TNB2 2715 TEMP_NBAT[7:0]
NV RAM AND RTC
NVRAMxx 2800 NVRAM[0] to NVRAM[7F] - 128 bytes, direct access, 0x2800 to 0x287F
WAKE 2880 WAKE_TMR[7:0]
STEMP1 2881 STEMP[15:8]
STEMP0 2882 STEMP[7:0]
BSENSE 2885 BSENSE[7:0]
PQ2 2886 U U U PQ[20:16]
PQ1 2887 PQ[15:8]
PQ0 2888 PQ[7:0]
RTC0 2890 RTC_WR RTC_RD U RTC_FAIL U U U U
RTC2 2892 RTC_SBSC[7:0]
RTC3 2893 U U RTC_SEC[5:0]
RTC4 2894 U U RTC_MIN[5:0]
RTC5 2895 U U U RTC_HR[4:0]
RTC6 2896 U U U U U RTC_DAY[2:0]
RTC7 2897 U U U RTC_DATE[4:0]
RTC8 2898 U U U U RTC_MO[3:0]
RTC9 2899 RTC_YR[7:0]
RTC11 289C U U U U TC_C[11:8]
RTC12 289D TC_C[7:0]
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Table 12. I/O RAM Locations in Numerical Order (continued)
Table 13. I/O RAM Locations in Alphabetical Order
NAME ADDR BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
RTC13 289E U U RTC_TMIN[5:0]
RTC14 289F U U U RTC_THR[4:0]
TEMP 28A0 TEMP_BSEL TEMP_PWR OSC_COMP TEMP_BAT TBYTE_BUSY TEMP_PER[2:0]
WF1 28B0 WF_CSTART WF_RST WF_RSTBIT WF_OVF WF_ERST WF_BADVDD U U
WF2 28B1 U WF_TEMP WF_TMR WF_RX WF_PB WF_DIO4 U WF_DIO55
MISC 28B2 SLEEP U WAKE_ARM U U U U U
WAKE_E 28B3 U EW_TEMP U EW_RX EW_PB EW_DIO4 U EW_DIO55
WDRST 28B4 WD_RST TEMP_START U U U U U U
MPU PORTS
P3 SFR B0 DIO_DIR[15:12] DIO[15:12]
P2 SFR A0 DIO_DIR[11:8] DIO[11:8]
P1 SFR 90 DIO_DIR[7:4] DIO[7:4]
P0 SFR 80 DIO_DIR[3:0] DIO[3:0]
FLASH
FLSH_ERASE SFR 94 FLSH_ERASE[7:0]
FLSH_CTL SFR B2 PREBOOT SECURE U U FLSH_PEND FLSH_PSTWR FLSH_MEEN FLSH_PWE
FLSH_
PGADR SFR B7 FLSH_PGADR[6:0] U
I2C
EEDATA SFR 9E EEDATA[7:0]
EECTRL SFR 9F EECTRL[7:0]
NAME LOCATION RST WK DIR DESCRIPTION
ADC_E 2704[4] 0 0 R/W Enables ADC and VREF. When disabled, reduces bias current.
ADC_DIV 2200[5] 0 0 R/W
ADC_DIV controls the rate of the ADC and FIR clocks.
The ADC_DIV setting determines whether MCK is divided by 4 or 8:
0 = MCK/4
1 = MCK/8
The resulting ADC and FIR clock is as shown below.
PLL_FAST = 0 PLL_FAST = 1
MCK 6.291456MHz 19.660800MHz
ADC_DIV = 0 1.572864MHz 4.9152MHz
ADC_DIV = 1 0.786432MHz 2.4576MHz
BCURR 2704[3] 0 0 R/W Connects a 100µA load to the battery selected by TEMP_BSEL.
BSENSE[7:0] 2885[7:0] – – R The result of the battery measurement.
CE_E 2106[0] 0 0 R/W CE enable.
CE_LCTN[5:0] 2109[5:0] 31 31 R/W CE program location. The starting address for the CE program is 1024 x CE_LCTN.
CHIP_ID[15:0] 2300[7:0]
2301[7:0]
0
0
0
0
R
R
Thesebytescontainthechipidentication.
CHIP_ID[15:0]:
71M6545T (11B4h)
71M6545HT (11BCh)
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
CHOP_E[1:0] 2106[3:2] 0 0 R/W
Chop enable for the reference bandgap circuit. The value of CHOP changes on the rising edge of MUXSYNC
according to the value in CHOP_E:
00 = toggle1 01 = positive 10 = reversed 11 = toggle
1except at the mux sync edge at the end of an accumulation interval.
Note: CHOP_E is the preferred mode for low-noise applications.
CHOPR[1:0] 2709[7:6] 00 00 R/W
The CHOP settings for the remote sensor.
00 = Auto chop. Change every MUX frame.
01 = Positive
10 = Negative
11 = Auto chop. Same as 00.
DIFF0_E 210C[4] 0 0 R/W EnablesIADC0-IADC1differentialconguration.
DIFF2_E 210C[5] 0 0 R/W EnablesIADC2-IADC3differentialconguration.
DIFF4_E 210C[6] 0 0 R/W EnablesIADC4-IADC5differentialconguration.
DIFF6_E 210C[7] 0 0 R/W EnablesIADC6-IADC7differentialconguration.
DIO_R2[2:0]
DIO_R3[2:0]
DIO_R4[2:0]
DIO_R5[2:0]
DIO_R6[2:0]
DIO_R7[2:0]
DIO_R8[2:0]
DIO_R9[2:0]
DIO_R10[2:0]
DIO_R11[2:0]
DIO_RPB[2:0]
2455[2:0]
2455[6:4]
2454[2:0]
2454[6:4]
2453[2:0]
2453[6:4]
2452[2:0]
2452[6:4]
2451[2:0]
2451[6:4]
2450[2:0]
0
0
0
0
0
0
0
0
0
0
0
- R/W
Connects PB and dedicated I/O pins DIO2 through DIO11 to internal resources. If more than one input is connected
tothesameresource,theMULTIPLEcolumnbelowspecieshowtheyarecombined.
DIO_Rx RESOURCE MULTIPLE
0 NONE –
1 Reserved OR
2 T0 (Timer0 clock or gate) OR
3 T1 (Timer1 clock or gate) OR
4 IO interrupt (int0) OR
5 IO interrupt (int1) OR
DIO_DIR[15:12]
DIO_DIR[11:8]
DIO_DIR[7:4]
DIO_DIR[3:0]
SFR B0[7:4]
SFR A0[7:4]
SFR 90[7:4]
SFR 80[7:4]
F F R/W
Programsthedirectionoftherst16DIOpins.1indicatesoutput.IgnoredifthepinisnotconguredasI/O.See
DIO_PV and DIO_PW for special option for the DIO0 and DIO1 outputs. See DIO_EEX for special option for DIO2
and DIO3. Note that the direction of DIO pins above 15 is set by DIOx[1]. See PORT_E to avoid power-up spikes.
DIO[15:12]
DIO[11:8]
DIO[7:4]
DIO[3:0]
SFR B0[3:0]
SFR A0[3:0]
SFR 90[3:0]
SFR 80[3:0]
F F R/W Thevalueontherst16DIOpins.Whenwritten,changesdataonpinsconguredasoutputs.Notethatthedatafor
DIO pins above 15 is set by DIOx[0].
DIO_EEX[1:0] 2456[7:6] 0 - R/W
When set, converts pins DIO3/DIO2 to interface with external EEPROM. DIO2 becomes SDCK and DIO3 becomes
bidirectional SDATA.
DIO_EEX[1:0] FUNCTION
00 Disable EEPROM interface
01 2-Wire EEPROM interface
10 3-Wire EEPROM interface
11 3-Wire EEPROM interface with separate DO (DIO3) and DI (DIO8) pins.
DIO_PV 2457[6] 0 – R/W Causes VARPULSE to be output on pin DIO1.
DIO_PW 2457[7] 0 – R/W Causes WPULSE to be output on pin DIO0.
DIO_PX 2458[7] 0 – R/W Causes XPULSE to be output on pin DIO6.
DIO_PY 2458[6] 0 – R/W Causes YPULSE to be output on pin DIO7.
EEDATA[7:0] SFR 9E 0 0 R/W Serial EEPROM interface data.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
EECTRL[7:0] SFR 9F 0 0 R/W
Serial EEPROM interface control.
STATUS
BIT NAME READ/
WRITE
RESET
STATE POLARITY DESCRIPTION
7 ERROR R 0 Positive 1 when an illegal command is
received.
6 BUSY R 0 Positive 1 when serial data bus is
busy.
5 RX_ACK R 1 Positive 1 indicates that the
EEPROM sent an ACK bit.
EQU[2:0] 2106[7:5] 0 0 R/W
Speciesthepowerequation.
EQU[2:0] DESCRIPTION ELEMENT 0 ELEMENT
1
ELEMENT
2
RECOMMENDED
MUX SEQUENCE
32 element 4W
3f Delta VA(IA-IB)/2 0 VC x IC IA VA IB VB IC VC
42 element 4W
3f Wye VA(IA-IB)/2 VB(IC-IB)/2 0 IA VA IB VB IC VC
52 element 4W
3f Wye VA x IA VB x IB VC x IC IA VA IB VB IC VC
Note: The available CE codes implement only equation 5. Contact your Maxim representative to obtain CE codes for
equation 3 or 4.
EX_XFER
EX_RTC1S
EX_RTC1M
EX_TCTEMP
EX_RTCT
EX_SPI
EX_EEX
EX_XPULSE
EX_YPULSE
EX_WPULSE
EX_VPULSE
2700[0]
2700[1]
2700[2]
2700[3]
2700[4]
2701[7]
2700[7]
2700[6]
2700[5]
2701[6]
2701[5]
0 0 R/W
Interrupt enable bits. These bits enable the XFER_BUSY, the RTC_1SEC, etc. The bits are set by hardware and
cannot be set by writing a 1. The bits are reset by writing 0. Note that if one of these interrupts is to enabled, its
corresponding 8051 EX enable bit must also be set.
EW_DIO4 28B3[2] 0 – R/W Connects DIO4 to the WAKE logic and permits DIO4 rising to wake the part. This bit has no effect unless DIO4 is
conguredasadigitalinput.
EW_DIO55 28B3[0] 0 – R/W Connects DIO55 to the WAKE logic and permits DIO55 rising to wake the part. This bit has no effect unless DIO55
isconguredasadigitalinput.
EW_PB 28B3[3] 0 – R/W ConnectsPBtotheWAKElogicandpermitsPBrisingtowakethepart.PBisalwaysconguredasaninput.
EW_RX 28B3[4] 0 – R/W Connects RX to the WAKE logic and permits RX rising to wake the part. See the WAKE description on page 84 for
de-bounce issues.
EW_TEMP 28B3[5] 0 – R/W Connects the temperature range check hardware to the WAKE logic and permits the range check hardware to wake
the part.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
FIR_LEN[1:0] 210C[2:1] 0 0 R/W
DeterminesthenumberofADCcyclesintheADCdecimationFIRlter.
PLL_FAST = 1:
FIR_LEN[1:0] ADC CYCLES
00 141
01 288
10 384
PLL_FAST = 0:
FIR_LEN[1:0] ADC CYCLES
00 135
01 276
10 Not Allowed
The ADC LSB size and full-scale values depend on the FIR_LEN[1:0] setting.
FLSH_
ERASE[7:0] SFR 94[7:0] 0 0 W
Flash Erase Initiate
FLSH_ERASEisusedtoinitiateeithertheFlashMassErasecycleortheFlashPageErasecycle.Specicpatterns
are expected for FLSH_ERASE in order to initiate the appropriate Erase cycle.
(default = 0x00).
0x55 = Initiate Flash Page Erase cycle. Must be proceeded by a write to FLSH_PGADR[6:0] (SFR 0xB7[7:1]).
0xAA = Initiate Flash Mass Erase cycle. Must be proceeded by a write to FLSH_MEEN and the ICE port must be
enabled.
Any other pattern written to FLSH_ERASE has no effect.
FLSH_MEEN SFR B2[1] 0 0 W
Mass Erase Enable
0 = Mass Erase disabled (default).
1 = Mass Erase enabled.
Must be re-written for each new Mass Erase cycle.
FLSH_PEND SFR B2[3] 0 0 R Indicatesthatatimedashwriteispending.Ifanotherashwriteisattempted,itisignored.
FLSH_
PGADR[6:0] SFR B7[7:1] 0 0 W
Flash Page Erase Address
Flash Page Address (page 0 thru 63) that is erased during the Page Erase cycle. (default = 0x00).
Must be re-written for each new Page Erase cycle.
FLSH_PSTWR SFR B2[2] 0 0 R/W
Enablestimedashwrites.When1,andifCE_E=1,ashwriterequestsarestoredinaone-elementdeepFIFO
and are executed when CE_BUSY falls. FLSH_PEND can be read to determine the status of the FIFO. If FLSH_
PSTWR=0orifCE_E=0,ashwritesareimmediate.
FLSH_PWE SFR B2[0] 0 0 R/W
Program Write Enable
0 = MOVX commands refer to External RAM Space, normal operation (default).
1 = MOVX @DPTR,A moves A to External Program Space (Flash) @ DPTR.
Thisbitisautomaticallyresetaftereachbytewrittentoash.Writestothisbitareinhibitedwheninterruptsare
enabled.
FLSH_RDE 2702[2] – – R IndicatesthattheashmaybereadbyICEorSPIslave.FLSH_RDE=(!SECURE)
FLSH_UNLOCK
[3:0] 2702[7:4] 0 0 R/W Mustbea‘2’toenableanyashmodication.SeethedescriptionofFlashsecurityformoredetails.
FLSH_WRE 2702[1] – – R IndicatesthattheashmaybewrittenthroughICEorSPIslaveports.
IE_XFER
IE_RTC1S
IE_RTC1M
IE_TCTEMP
IE_RTCT
IE_SPI
IE_EEX
IE_XPULSE
IE_YPULSE
IE_WPULSE
IE_VPULSE
SFR E8[0]
SFR E8[1]
SFR E8[2]
SFR E8[3]
SFR E8[4]
SFR F8[7]
SFR E8[7]
SFR E8[6]
SFR E8[5]
SFR F8[4]
SFR F8[3]
0 0 R/W
Interruptagsforexternalinterrupts2,5,and6.Theseagsmonitorthesourceoftheint2,int5,andint6interrupts
(externalinterruptstotheMPUcore).Theseagsaresetbyhardwareandmustbeclearedbythesoftwareinterrupt
handler.TheIEX2(SFR0xC0[1])andIEX6(SFR0xC0[5])interruptagsareautomaticallyclearedbytheMPUcore
when it vectors to the interrupt handler. IEX2 and IEX6 must be cleared by writing zero to their corresponding bit
positions in SFR 0xC0, while writing ones to the other bit positions that are not being cleared.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
INTBITS 2707[6:0] – – R Interrupt inputs. The MPU may read these bits to see the input to external interrupts INT0, INT1, up to INT6. These
bits do not have any memory and are primarily intended for debug use.
MPU_DIV[2:0] 2200[2:0] 0 0 R/W
MPU clock rate is:
MPU Rate = MCK Rate x 2-(2+MPU_DIV[2:0]).
The maximum value for MPU_DIV[2:0] is 4. Based on the default values of the PLL_FAST bit and MPU_DIV[2:0],
the power up MPU rate is 6.29MHz/4 = 1.5725MHz. The minimum MPU clock rate is 38.4kHz when
PLL_FAS T = 1.
MUX2_SEL[3:0] 2104[3:0] 0 0 R/W Selects which ADC input is to be converted during time slot 2.
MUX3_SEL[3:0] 2104[7:4] 0 0 R/W Selects which ADC input is to be converted during time slot 3.
MUX4_SEL[3:0] 2103[3:0] 0 0 R/W Selects which ADC input is to be converted during time slot 4.
MUX5_SEL[3:0] 2103[7:4] 0 0 R/W Selects which ADC input is to be converted during time slot 5.
MUX6_SEL[3:0] 2102[3:0] 0 0 R/W Selects which ADC input is to be converted during time slot 6.
MUX7_SEL[3:0] 2102[7:4] 0 0 R/W Selects which ADC input is to be converted during time slot 7.
MUX8_SEL[3:0] 2101[3:0] 0 0 R/W Selects which ADC input is to be converted during time slot 8.
MUX9_SEL[3:0] 2101[7:4] 0 0 R/W Selects which ADC input is to be converted during time slot 9.
MUX10_SEL[3:0] 2100[3:0] 0 0 R/W Selects which ADC input is to be converted during time slot 10.
MUX_DIV[3:0] 2100[7:4] 0 0 R/W MUX_DIV[3:0] is the number of ADC time slots in each MUX frame. The maximum number of time slots is 11.
PB_STATE SFR F8[0] 0 0 R The de-bounced state of the PB pin.
PERR_RD
PERR_WR
SFR FC[6]
SFR FC[5] 0 0 R/W The IC sets these bits to indicate that a parity error on the remote sensor has been detected. Once set, the bits are
remembered until they are cleared by the MPU.
PLL_OK SFR F9[4] 0 0 R Indicates that the clock generation PLL is settled.
PLL_FAST 2200[4] 0 0 R/W
Controls the speed of the PLL and MCK.
1 = 19.66 MHz (XTAL x 600)
0 = 6.29MHz (XTAL x 192)
PLS_
MAXWIDTH[7:0] 210A[7:0] FF FF R/W
PLS_MAXWIDTH[7:0] determines the maximum width of the pulse (low-going pulse if PLS_INV = 0 or high-going
pulse if PLS_INV = 1). The maximum pulse width is (2 x PLS_MAXWIDTH[7:0] + 1) x TI. Where TI is PLS_
INTERVAL[7:0] in units of CK_FIR clock cycles. If PLS_INTERVAL[7:0] = 0 or PLS_MAXWIDTH[7:0] = 255, no pulse
width checking is performed and the output pulses have 50% duty cycle.
PLS_
INTERVAL[7:0] 210B[7:0] 0 0 R/W
PLS_INTERVAL[7:0] determines the interval time between pulses. The time between output pulses is PLS_
INTERVAL[7:0] x 4 in units of CK_FIR clock cycles. If PLS_INTERVAL[7:0] = 0, the FIFO is not used and pulses are
output as soon as the CE issues them. PLS_INTERVAL[7:0] is calculated as follows:
PLS_INTERVAL[7:0] = Floor ( Mux frame duration in CK_FIR cycles/
CE pulse updates per Mux frame/4 )
For example, since the 71M654xT CE code is written to generate 6 pulses in one integration interval, when the FIFO is
enabled(i.e.,PLS_INTERVAL[7:0]≠0)andthattheframedurationis1950CK_FIRclockcycles,PLS_INTERVAL[7:0]
shouldbewrittenwithFloor(1950/6/4)=81sothatthevepulsesareevenlyspacedintimeovertheintegrationinterval
and the last pulse is issued just prior to the end of the interval.
PLS_INV 210C[0] 0 0 R/W Inverts the polarity of WPULSE, VARPULSE, XPULSE and YPULSE. Normally, these pulses are active low. When
inverted, they become active high.
PORT_E 270C[5] 0 0 R/W Enables outputs from the pins DIO0–DIO14. PORT_E = 0 after reset and power-up blocks the momentary output
pulse that would occur on DIO0 to DIO14.
PQ[20:0]
2886[4:0]
2887[7:0]
2888[7:0]
0 0 R Temperature compensation value computed by the quadratic compensation formula.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
PQMASK 2511[2:0] 0 0 R/W
Sets the length of the PQ mask. The mask is ANDed with the last four bits of PQ according to the table below.
PQMASK also determines the length of PULSE_AUTO in TMUX.
PQMASK MASK PULSE_AUTO WIDTH
000 0000 1s
001 1000 2s
010 1100 4s
011 1110 8s
100 1111 16s
PRE_E 2704[5] 0 0 R/W Enablesthe8xpreamplier.
PREBOOT SFRB2[7] – – R Indicates that preboot sequence is active.
RCMD[4:0] SFR FC[4:0] 0 0 R/W When the MPU writes a non-zero value to RCMD[4:0], the IC issues a command to the appropriate remote sensor.
When the command is complete, the IC clears RCMD[4:0].
RESET 2200[3] 0 0 W When set, writes a one to WF_RSTBIT and then causes a reset.
RFLY_DIS 210C[3] 0 0 R/W Controls how the IC drives the power pulse for the 71M6x03. When set, the power pulse is driven high and low.
Whencleared,itisdrivenhighfollowedbyanopencircuity-backinterval.
RMT2_E 2709[3] 0 0 R/W Enables the remote interface.
RMT4_E 2709[4] 0 0 R/W Enables the remote interface.
RMT6_E 2709[5] 0 0 R/W Enables the remote interface.
RMT_RD[15:8]
RMT_RD[7:0]
2602[7:0]
2603[7:0] 0 0 R Response from remote read request.
RTC_FAIL 2890[4] 0 0 R/W Indicates that a count error has occurred in the RTC and that the time is not trustworthy. This bit can be cleared by
writing a 0.
RTC_RD 2890[6] 0 0 R/W Freezes the RTC shadow register so it is suitable for MPU reads. When RTC_RD is read, it returns the status of the
shadow register: 0 = up to date, 1 = frozen.
RTC_SBSC[7:0] 2892[7:0] – – R Time remaining until the next 1 second boundary. LSB = 1/256 second.
RTC_TMIN[5:0] 289E[5:0] 0 – R/W The target minutes register. See RTC_THR below.
RTC_THR[4:0] 289F[4:0] 0 – R/W The target hours register. The RTC_T interrupt occurs when RTC_MIN becomes equal to RTC_TMIN and RTC_HR
becomes equal to RTC_THR.
RTC_WR 2890[7] 0 0 R/W
Freezes the RTC shadow register so it is suitable for MPU writes. When RTC_WR is cleared, the contents of the
shadow register are written to the RTC counter on the next RTC clock (~500 Hz). When RTC_WR is read, it returns
1 as long as RTC_WR is set. It continues to return one until the RTC counter actually updates.
RTC_SEC[5:0]
RTC_MIN[5:0]
RTC_HR[4:0]
RTC_DAY[2:0]
RTC_DATE[4:0]
RTC_MO[3:0]
RTC_YR[7:0]
2893[5:0]
2894[5:0]
2895[4:0]
2896[2:0]
2897[4:0]
2898[3:0]
2899[7:0]
–
–
–
–
–
–
–
–
–
–
–
–
–
–
R/W
The RTC interface registers. These are the year, month, day, hour, minute and second parameters for the RTC. The
RTCissetbywritingtotheseregisters.Year00andallothersdivisibleby4aredenedasaleapyear.
SEC 00 to 59
MIN 00 to 59
HR 00 to 23 (00 = Midnight)
DAY 01 to 07 (01 = Sunday)
DATE 01 to 31
MO 01 to 12
YR 00 to 99
Each write operation to one of these registers must be preceded by a write to 0x20A0.
RTM_E 2106[1] 0 0 R/W Real Time Monitor enable. When 0, the RTM output is low.
RTM0[9:8]
RTM0[7:0]
RTM1[7:0]
RTM2[7:0]
RTM3[7:0]
210D[1:0]
210E[7:0]
210F[7:0]
2110[7:0]
2111[7:0]
0
0
0
0
0
0
0
0
0
0
R/W
Four RTM probes. Before each CE code pass, the values of these registers are serially output on the RTM pin. The
RTM registers are ignored when RTM_E = 0. Note that RTM0 is 10 bits wide. The others assume the upper two bits
are 00.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
SBASE:[10:0] 2519[2:0]
251A[7:0] 0 0 R/W Base temperature for limit checking
SECURE SFR B2[6] 0 0 R/W Inhibitserasureofpage0andashaddressesabovethebeginningofCEcodeasdenedbyCE_LCTN[5:0].Also
inhibitsthereadofashviatheSPIandICEport.
SFILT 251D[3:0] 0 0 R/W Filter variable for wake on temperature extremes.
SLEEP 28B2[7] 0 0 W Puts the part to SLP mode. Ignored if system power is present. The part wakes when the Wake timer expires, when
push button is pushed, or when system power returns.
SLOT_EXT[3:0] 2112[3:0] 0 0 R/S If non-zero, will extend the duration of time slot zero by up to 15 extra crystal cycles. The ADC result for time slot
zerowillbeleft-shiftedninebitsifSLOT_EXT=0andfourbitsifSLOT_EXT≠0.
SMAX[6:0] 251B[6:0] 0 0 R/W Maximum temperature for limit checking
SMIN[6:0] 251C[6:0] 0 0 R/W Minimum temperature for limit checking
SPI_CMD[7:0] SFR FD[7:0] – – R SPI command register for the 8-bit command from the bus master.
SPI_E 270C[4] 1 1 R/W SPI port enable.
SPI_SAFE 270C[3] 0 0 R/W Limits SPI writes to SPI_CMD and a 16-byte region in DRAM. No other writes are permitted.
SPI_STAT[7:0] 2708[7:0] 0 0 R
SPI_STAT contains the status results from the previous SPI transaction.
Bit 7: Ready error: The 71M654xT was not ready to read or write as directed by the previous command.
Bit 6: Read data parity: This bit is the parity of all bytes read from the 71M654xT in the previous command. Does not
include the SPI_STAT byte.
Bit 5: Write data parity: This bit is the overall parity of the bytes written to the 71M654xT in the previous command. It
includes CMD and ADDR bytes.
Bit 4-2: Bottom 3 bits of the byte count. Does not include ADDR and CMD bytes. One, two, and three byte
instructions return 111.
Bit 1: SPI FLASH mode: This bit is zero when the TEST pin is zero.
Bit0:SPIFLASHmodeready:UsedinSPIFLASHmode.Indicatesthattheashisreadytoreceiveanotherwrite
instruction.
STEMP[15:0] 2881[7:0]
2882[7:0] – – R The result of the temperature measurement.
SUM_SAMPS[12:8]
SUM_SAMPS[7:0]
2107[4:0]
2108[7:0] 0 0 R/W The number of multiplexer cycles per XFER_BUSY interrupt. Maximum value is 8191 cycles.
TC_A[9:0] 2508[1:0]
2509[7:0] 0 0 R/W Temperature compensation factor for quadratic compensation.
TC_B[11:0] 250A[3:0]
205B[7:0] 0 0 R/W Temperature compensation factor for quadratic compensation.
TC_C[11:0] 289C[3:0]
289D[7:0] 0 0 R/W Temperature compensation factor for quadratic compensation.
TEMP_22[12:8]
TEMP_22[7:0]
230A[4:0]
230B[7:0] 0 – R Storage location for STEMP at 22NC. STEMP is an 11-bit word.
TEMP_BAT 28A0[4] 0 – R/W Causes VBAT to be measured whenever a temperature measurement is performed.
TEMP_BSEL 28A0[7] 0 – R/W Selects which battery is monitored by the temperature sensor: 1 = VBAT, 0 = VBAT_RTC
TBYTE_BUSY 28A0[3] 0 0 R Indicates that hardware is still writing the 0x28A0 byte. Additional writes to this byte will be locked out while it is one.
Write duration could be as long as 6ms.
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Table 13. I/O RAM Locations in Alphabetical Order (continued)
NAME LOCATION RST WK DIR DESCRIPTION
TEMP_PER[2:0] 28A0[2:0] 0 – R/W
Sets the period between temperature measurements. Automatic measurements can be enabled in any mode (MSN,
BRN, or SLP). TEMP_PER = 0 disables automatic temperature updates, in which case TEMP_START may be used
by the MPU to initiate a one-shot temperature measurement.
TEMP_PER TIME (s)
0 No temperature updates
1-6 2(3+TEMP_PER)
7 Continuous updates
In automatic mode, TEMP_START is the indicator of the temperature sensor status:
TEMP_START = 1 (temperature sensor is busy, cannot measure temperature)
TEMP_START = 0 (temperature sensor is idle, can measure temperature)
TEMP_PWR 28A0[6] 0 – R/W
Selects the power source for the temp sensor:
1 = VV3P3D, 0 = VBAT_RTC. This bit is ignored in SLP mode, where the temp sensor is always
powered by VBAT_RTC.
TEMP_START 28B4[6] 0 0 R/W
When TEMP_PER = 0 automatic temperature measurements are disabled, and TEMP_START may be set by the
MPU to initiate a one-shot temperature measurement. TEMP_START is ignored in SLP mode. Hardware clears
TEMP_START when the temperature measurement is complete.
In automatic mode, TEMP_START is the indicator of the temperature sensor status:
TEMP_START = 1 (temperature sensor is busy, cannot measure temperature)
TEMP_START = 0 (temperature sensor is idle, can measure temperature)
TMUX[5:0] 2502[5:0] – – R/W Selects one of 32 signals for TMUXOUT.
TMUX2[4:0] 2503[4:0] – – R/W Selects one of 32 signals for TMUX2OUT.
TMUXRA[2:0] 270A[2:0] 000 000 R/W The TMUX setting for the remote isolated sensor (71M6x03).
VREF_CAL 2704[7] 0 0 R/W Brings the ADC reference voltage out to the VREF pin. This feature is disabled when VREF_DIS=1.
VREF_DIS 2704[6] 0 1 R/W Disables the internal ADC voltage reference.
VSTAT[2:0] SFR F9[2:0] – – R
This word describes the source of power and the status of VDD.
000 System Power OK. VV3P3A>3.0v. Analog modules are functional and
accurate. [V3AOK,V3OK] = 11
001 System Power Low. 2.8v<VV3P3A<3.0v. Analog modules not accurate.
Switchover to battery power is imminent. [V3AOK,V3OK] = 01
010 Battery power and VDD OK. VDD>2.25v. Full digital functionality.
[V3AOK,V3OK] = 00, [VDDOK,VDDgt2] = 11
011
Battery power and VDD>2.0. Flash writes are inhibited. If the TRIMVDD[5]
fuse is blown, PLL_FAST (I/O RAM 0x2200[4]) is cleared.
[V3AOK,V3OK] = 00, [VDDOK,VDDgt2] = 01
101
Battery power and VDD<2.0. When VSTAT=101, processor is nearly out of
voltage. Processor failure is imminent.
[V3AOK,V3OK] = 00, [VDDOK,VDDgt2] = 00
WAKE_ARM 28B2[5] 0 – R/W Arms the WAKE timer and loads it with WAKE_TMR[7:0]. When SLEEP or LCD_ONLY is asserted by the MPU, the
WAKE timer becomes active.
WAKE_TMR[7:0] 2880[7:0] 0 – R/W Timer duration is WAKE_TMR+1 seconds.
WD_RST 28B4[7] 0 0 W Reset the WD timer. The WD is reset when a 1 is written to this bit. Writing a one clears and restarts the watch dog
timer.
WF_DIO4 28B1[2] 0 – R DIO4wakeagbit.IfDIO4isconguredtowakethepart,thisbitissetwheneverthede-bouncedversionofDIO4
rises.ItisheldinresetifDI04isnotconguredforwakeup.
WF_DIO55 28B1[0] 0 – R DIO55wakeagbit.IfDIO55isconguredtowakethepart,thisbitissetwheneverthede-bouncedversionof
DIO55rises.ItisheldinresetifDI055isnotconguredforwakeup.
WF_TEMP 28B1[6] 0 – R Indicates that the temperature range check hardware caused the part to wake up.
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CE Interface Description
CE Program
The CE performs the precision computations necessary to
accurately measure energy. These computa tions include
offset cancellation, phase compensation, product smooth-
ing, product summation, frequency detection, VAR calcula-
tion, sag detection and voltage phase measurement.
The CE program is supplied by Maxim Integrated as a
data image that can be merged with the MPU operational
code for meter applications. Typically, the CE program
provided with the demonstration code covers most appli-
cations and does not need to be modified. Other varia-
tions of CE code are available. Contact your local Maxim
Integrated representative to obtain the appropriate CE
code required for a specific application.
CE Data Format
All CE words are 4 bytes. Unless specified otherwise,
they are in 32-bit two’s complement format
(-1 = 0xFFFFFFFF). Calibration para meters are defined in
flash memory (or external EEPROM) and must be copied
to CE data memory by the MPU before enabling the CE.
Internal variables are used in internal CE calculations.
Input variables allow the MPU to control the behavior of
the CE code. Output variables are outputs of the CE cal-
culations. The corresponding MPU address for the most
signi ficant byte is given by 0x0000 + 4 x CE_address and
by 0x0003 + 4 x CE_address for the least significant byte.
Constants
• Sampling Frequency: 2520.62Hz.
• F0: Frequency of the mains phases (typically 50Hz or
60Hz).
• IMAX: RMS current corresponding to 250mV peak
(176.8 mVRMS) at the inputs IA and IB. IMAX needs
to be adjusted if the preamplifier is activated for the
IAP-IAN inputs. For a 250μΩ shunt resistor, IMAX
becomes 707A (176.8 mVRMS/250FI = 707.2ARMS).
• VMAX: RMS voltage corresponding to 250mV peak at
the VA and VB inputs.
• NACC: Accumulation count for energy measurements
is SUM_SAMPS[12:0]. The duration of the accumu-
lation interval for energy measurements is SUM_
SAMPS[12:0]/FS.
• X: Gain constant of the pulse generators. Its value is
determined by PULSE_FAST and PULSE_SLOW.
• Voltage LSB (for sag threshold) = VMAX x 7.8798
x10-9 V.
The system constants IMAX and VMAX are used by the
MPU to convert internal digital quantities (as used by the
CE) to external, i.e., metering quantities. Their values are
determined by the scaling of the voltage and current sen-
sors used in an actual meter.
Environment
Before starting the CE using the CE_E bit (I/O RAM
0x2106[0]), the MPU has to establish the proper environ-
ment for the CE by implementing the following steps:
• Locate the CE code in flash memory using CE_LCTN[5:0].
• Load the CE data into RAM.
• Establish the equation to be applied in EQU[2:0].
• Establish the number of samples per accumulation
period in SUM_SAMPS[12:0].
• Establish the number of cycles per ADC multiplexer
frame (MUX_DIV[3:0]).
• Apply proper values to MUXn_SEL, as well as proper
selections for DIFFn_E and RMT_E in order to config-
ure the analog inputs.
• Initialize any MPU interrupts, such as CE_BUSY,
XFER_BUSY, or the power failure detection interrupt.
• VMAX = 600V, IMAX = 707A, and kH = 1Wh/pulse are
assumed as default settings
When different CE codes are used, a different set of envi-
ronment parameters need to be established. The exact
NAME LOCATION RST WK DIR DESCRIPTION
WAKE_ARM 28B2[5] 0 – R/W Arms the WAKE timer and loads it with WAKE_TMR[7:0]. When SLEEP or LCD_ONLY is asserted by the MPU, the
WAKE timer becomes active.
WF_PB 28B1[3] – – R Indicates that the PB caused the part to wake.
WF_RX 28B1[4] 0 – R Indicates that RX caused the part to wake.
WF_CSTART
WF_RST
WF_RSTBIT
WF_OVF
WF_ERST
WF_BADVDD
28B0[7]
28B0[6]
28B0[5]
28B0[4]
28B0[3]
28B0[2]
0
1
0
0
0
0
– R Indicates that the Reset pin, Reset bit, ERST pin, Watchdog timer, the cold start detector, or bad VBAT caused the
part to reset.
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values for these parameters are listed in the Application
Notes and other documentation which accompanies the
CE code.
The CE details described in this data sheet should
be considered typical and may not, in aggregate, be
indicative of any particular CE code. Contact your Maxim
Integrated representative for details about available stan-
dard CE codes.
CE Calculations
The MPU selects the basic configuration for the CE by
setting the EQU variable.
CE Input Data
Data from the AFE is placed into CE memory by hardware
at ADC0-ADC10. Table 15 describes the process.
Status and Control
The CESTATUS register (0x80) contains bits that reflect
the status of the signals that are applied to the CE.
CECONFIG (0x20) contains bits that control basic opera-
tion of the compute engine.
The CE code supports registers to establish the sag
threshold and gain for each of the input channels. When
the input RMS voltage level falls below an established
level, a warning is posted to the MPU. This level is called
the sag threshold, and it is set in the SAG_THR register.
Gain for each channel is adjusted in the GAIN_ADJ0
(voltage), GAIN_ADJ1 (current channel A) and GAIN_
ADJ2 (current channel B).
Transfer Variables
After each pass through CE program code, the CE
asserts a XFER_BUSY interrupt. This informs the MPU
that new data is available. It is the responsibility of MPU
code to retrieve the data from the CE in a timely manner.
Pulse Generation
WRATE (CE RAM 0x21) along with the PULSE_SLOW
and PULSE_FAST bits control the number of pulses that
are generated per measured Wh and VARh quantities. The
pulse rate is proportional to the WRATE value for a given
energy. The meter constant Kh is derived from WRATE as
the amount of energy measured for each pulse. That is,
if Kh = 1Wh/pulse, a power applied to the meter of 120 V
and 30 A results in one pulse per second; if the load is 240
V at 150 A, ten pulses per second are generated.
Normally, the CE takes the values from W0SUM_X
and VAR0SUM_X and moves them to APULSEW and
APULSER, respectively. Then, pulse generation logic in
the CE creates the actual pulses. However, the MPU can
take direct control of the pulse generation process by
setting EXT_PULSE = 1. In this case, the MPU sets the
pulse rate by directly loading APULSEW and APULSER.
Note that since creep management is an MPU function,
when the CE manages pulse output (EXT_PULSE = 0)
creep management is disabled.
The maximum pulse rate is 3 x FS = 7.56kHz.
The maximum time jitter is 1/6 of the multiplexer cycle
period(nominally67μs)andisindependentofthenum-
ber of pulses measured. Thus, if the pulse generator is
monitored for one second, the peak jitter is 67ppm. After
10 seconds, the peak jitter is 6.7ppm. The average jit-
ter is always zero. If it is attempted to drive either pulse
generator faster than its maximum rate, it simply outputs
at its maximum rate without exhibiting any rollover char-
acteristics. The actual pulse rate, using WSUM as an
example, is:
S
46
RATE Hz
=
where FS = sampling frequency (2520.6 Hz), X = Pulse
speed factor derived from the CE variables PULSE_
SLOW and PULSE_FAST.
Figure 17, Figure 18, and Figure 19 show the data flow
through the CE in simplified form. Functions not shown
include delay compensation, sag detection, scaling, and
the processing of meter equations.
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Table 14. Power Equations
CE Flow Diagrams
Table 15. CE Raw Data Access Locations
*Remote interface data.
EQU[2:0] WATT AND VAR FORMULA
(WSUM/VARSUM)
W0SUM/
VAR0SUM
W1SUM/
VAR1SUM
W2SUM/
VAR2SUM
I0SQ
SUM
I1SQ
SUM
I2SQ
SUM
3VA x (IA-IB/2) + VC x IC
(2 element 4W 3<phi>Delta) VA x (IA-IB)/2 — VC x IC IA-IB IB IC
4VA x (IA-IB)/2 + VB(IC-IB)/2
(2 element 4W 3<phi>Wye) VA x (IA-IB)/2 VB x (IC-IB) — IA-IB IC-IB IC
5VA x IA+VB x IB + VC x IC
(3 element 4W 3<ph> Wye) VA x IA VB x IB VC x IC IA IB IC
PIN MUXn_SEL HANDLE CE RAM LOCATION
DIFF0_E DIFF0_E
0 1 0 1
IADC0 0 000
IADC1 1 1
RMT2_E, DIFF2_E RMT2_E, DIFF2_E
0,0 0,1 1,0 1,1 0,0 0,1 1,0 1,1
IADC2 2 2 - - 22 2* 2*
IADC3 3 3
RMT4_E, DIFF4_E RMT4_E, DIFF4_E
0,0 0,1 1,0 1,1 0,0 0,1 1,0 1,1
IADC4 4 4 - - 44 4* 4*
IADC5 5 5
RMT6_E, DIFF6_E RMT6_E, DIFF6_E
0,0 0,1 1,0 1,1 0,0 0,1 1,0 1,1
IADC6 6 6 - - 66 6* 6*
IADC7 7 7
TherearenocongurationbitsforVADC8,9,10
VADC8 (VA) 8 8
VADC9 (VB) 9 9
VADC10 (VC) 10 10
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Table 16. CE Status Register
Table 17. CE Configuration Register
CESTATUS BIT NAME DESCRIPTION
31:4 Not used These unused bits are always zero.
3 F0 F0 is a square wave at the exact fundamental input frequency.
2 SAG_C Normally zero. Becomes one when VB remains below SAG_THR for SAG_CNT samples.
Does not return to zero until VB rises above SAG_THR.
1 SAG_B Normally zero. Becomes one when VB remains below SAG_THR for SAG_CNT samples.
Does not return to zero until VB rises above SAG_THR.
0 SAG_A Normally zero. Becomes one when VA remains below SAG_THR for SAG_CNT samples.
Does not return to zero until VA rises above SAG_THR.
CECONFIG BIT NAME DEFAULT DESCRIPTION
22 EXT_TEMP 0 When 1, the MPU controls temperature compensation through the GAIN_ADJn
registers (CE RAM 0x40-0x42), when 0, the CE is in control.
21 EDGE_INT 1 When 1, XPULSE produces a pulse for each zero-crossing of the mains phase
selected by FREQSEL[1:0] , which can be used to interrupt the MPU.
20 SAG_INT 1 When 1, activates YPULSE output when a sag condition is detected.
19:8 SAG_CNT 252
(0xFC)
The number of consecutive voltage samples below SAG_THR (CE RAM 0x24)
before a sag alarm is declared. The default value is equivalent to 100 ms.
7:6 FREQSEL[1:0] 0
FREQSEL[1:0] selects the phase to be used for the frequency monitor, sag
detection, and for the zero crossing counter (MAINEDGE_X).
FREQ SEL[1:0] PHASE SELECTED
0 0 A
0 1 B*
1 X Not allowed
5 EXT_PULSE 1
When zero, causes the pulse generators to respond to internal data (WPULSE =
WSUM_X, VPULSE = VARSUM_X). Otherwise, the generators respond to values
the MPU places in APULSEW and APULSER.
4:2 Reserved 0 Reserved.
1 PULSE_FAST 0
When PULSE_FAST = 1, the pulse generator input is increased 16x. When
PULSE_SLOW = 1, the pulse generator input is reduced by a factor of 64. These
two parameters control the pulse gain factor X (see table below). Allowed values
are either 1 or 0. Default is 0 for both (X = 6).
0 PULSE_SLOW 0
PULSE_FAST PULSE_SLOW X
00 1.5 x 22 = 6
10 1.5 x 26 = 96
01 1.5 x 2-4 = 0.09375
11 Do not use
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Table 18. Sag Threshold and Gain Adjustment Registers
Table 19. CE Transfer Registers
CE ADDRESS NAME DEFAULT DESCRIPTION
0x24 SAG_THR 2.39 x 107
The voltage threshold for sag warnings. The default value is equivalent to 113V
peak or 80 VRMS if VMAX = 600VRMS.
RMS
9
V2
SAG_THR
VMAX 7.8798 10
−
⋅
=
⋅⋅
0x40 GAIN_ADJ0 16384 This register scales the voltage measurement channels VADC8 (VA), VADC9 (VB)
AND VADC10 (VC). The default value of 16384 is equivalent to unity gain (1.000).
0x41 GAIN_ADJ1 16384 This register scales the neutral current channel for neutral current. The default
value of 16384 is equivalent to unity gain (1.000).
0x42 GAIN_ADJ2 16384 This register scales the IA current channel for Phase A. The default value of 16384
is equivalent to unity gain (1.000).
0x43 GAIN_ADJ3 16384 This register scales the IB current channel for Phase B. The default value of
16384 is equivalent to unity gain (1.000).
0x44 GAIN_ADJ4 16384 This register scales the IC current channel for Phase C. The default value of
16384 is equivalent to unity gain (1.000).
CE ADDRESS NAME DESCRIPTION
0x84† WSUM_X The signed sum: W0SUM_X+W1SUM_X. Not used for EQU[2:0] = 0 and EQU[2:0] = 1.
0x85 W0SUM_X The sum of Wh samples from each wattmeter element.
LSB = 9.4045 x 10-13 x VMAX x IMAX Wh (local)
LSB = 1.55124 x 10-12 x VMAX x IMAX Wh (remote)
0x86 W1SUM_X
0x87 W2SUM_X
0x88† VARSUM_X The signed sum: VAR0SUM_X+VAR1SUM_X. Not used for EQU[2:0] = 0 and EQU[2:0] = 1.
0x89 VAR0SUM_X The sum of VARh samples from each wattmeter element.
LSB = 9.4045 x 10-13 x VMAX x IMAX VARh (local)
LSB = 1.55124 x 10-12 x VMAX x IMAX VARh (remote)
0x8A VAR1SUM_X
0x8B VAR2SUM_X
0x8C I0SQSUM_X
The sum of squared current samples from each element.
LSB = 9.4045 x 10-13 IMAX2 A2h (local)
LSB = 2.55872 x 10-12 x IMAX2 A2h (remote)
0x8D I1SQSUM_X
0x8E I2SQSUM_X
0x8F I3SQSUM_X
0x90 V0SQSUM_X The sum of squared voltage samples from each element.
LSB= 9.4045 x 10-13 VMAX2 V2h (local)
LSB= 9.40448 x 10-13 x VMAX2 V2h (remote)
0x91 V1SQSUM_X
0x92 V2SQSUM_X
0x82 FREQ_X
Fundamental frequency:
6
32
6
32
2520.6Hz
LSB 0.509 10 Hz (for Local)
2
2520.6Hz
LSB 0.587 10 Hz (for Remote)
2
−
−
≡ ≈⋅
≡ ≈⋅
0x83 MAINEDGE_X The number of edge crossings of the selected voltage in the previous ac cumulation interval.
Edge crossings are either direction and are debounced.
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Table 20. CE Pulse Generation Parameters
CE ADDRESS NAME DEFAULT DESCRIPTION
0x21 WRATE 547
ACC
VMAX IMAX K
Kh Wh / pulse
WRATE N X
⋅⋅
= ⋅
⋅⋅
where:
K = 66.1782 (Local Sensors)
K = 109.1587 (Remote Sensor)
NACC = SUM_SAMPS[12:0] (CE RAM 0x23)
X is a factor determined by PULSE_FAST and PULSE_SLOW. See
CECONFIGdenitionformoreinformation
The default value yields 1.0 Wh/pulse for VMAX = 600 V and IMAX = 208
A. The maximum value for WRATE is 32,768 (215).
0x22 KVAR 6444 Scale factor for VAR measurement.
0x23 SUM_SAMPS 2520 SUM_SAMPS (NACC).
0x45 APULSEW 0
Wh pulse (WPULSE) generator input to be updated by the MPU when
using external pulse generation. The output pulse rate is:
APULSEW x fS x 2-32 * WRATE x X x 2-14.
This input is buffered and can be updated by the MPU during a conversion
interval. The change takes effect at the beginning of the next interval.
0x46 WPULSE_CTR 0 WPULSE counter.
0x47 WPULSE_FRAC 0 Unsigned numerator, containing a fraction of a pulse. The value in this
register always counts up towards the next pulse.
0x48 WSUM_ACCUM 0 Roll-over accumulator for WPULSE.
0x49 APULSER 0 VARh (VPULSE) pulse generator input.
0x4A VPULSE_CTR 0 VPULSE counter.
0x4B VPULSE_FRAC 0 Unsigned numerator, containing a fraction of a pulse. The value in this
register always counts up towards the next pulse.
0x4C VSUM_ACCUM 0 Roll-over accumulator for VPULSE.
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Table 21. Other CE Parameters
CE ADDRESS NAME DEFAULT DESCRIPTION
0x25 QUANT_VA 0
Compensation factors for truncation and noise in voltage, current, real energy
and reactive energy for phase A.
0x26 QUANT_IA 0
0x27 QUANT_A 0
0x28 QUANT_VARA 0
0x29 †QUANT_VB 0
Compensation factors for truncation and noise in voltage, current, real energy
and reactive energy for phase B.
0x2A QUANT_IB 0
0x2B QUANT_B 0
0x2C QUANT_VARB 0
0x2D QUANT_VC 0
Compensation factors for truncation and noise in voltage, current, real energy
and reactive energy for phase C.
0x2E QUANT_IC 0
0x2F QUANT_C 0
0x30 QUANT_VARC 0
0x38 0x43453431 CElenameidentierinASCIIformat(CE41a01f).Thesevaluesare
overwritten as soon as the CE starts
0x39 0x6130316B
0x3A 0x00000000
LSB weights for use with Local Sensors:
QUANT_Ix_LSB = 5.08656 · 10-13 · IMAX2 (Amps2)
QUANT_Wx_LSB = 1.04173 · 10-9 · VMAX · IMAX (Watts)
QUANT_VARx_LSB = 1.04173 · 10-9 · VMAX · IMAX (Vars)
LSB weights for use with the 71M6x03 isolated sensors:
QUANT_Ix_LSB = 1.38392 · 10-12 · IMAX2 (Amps2)
QUANT_Wx_LSB = 1.71829 · 10-9 · VMAX · IMAX (Watts)
QUANT_VARx_LSB = 1.71829 · 10-9 · VMAX · IMAX (Vars)
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Table 22. CE Calibration Parameters
CE ADDRESS NAME DEFAULT DESCRIPTION
0x10 CAL_IA 16384 These constants control the gain of their respective channels. The nominal
value for each parameter is 214 = 16384. The gain of each channel is directly
proportional to its CAL parameter. Thus, if the gain of a channel is 1% slow, CAL
should be increased by 1%. Refer to the 71M6x03 Demo Board User’s Manual for
the equations to calculate these calibration parameters.
0x11 CAL_VA 16384
0x13 CAL_IB 16384
0x14 CAL_VB 16384
0x12 PHADJ_A 0
These constants control the CT phase compensation. Com pensation does not
occur when PHADJ_X = 0. As PHADJ_X is increased, more compensation (lag) is
introduced. The range is P 215 – 1. If it is desired to delay the current by the angle
F, the equations are:
20 0.02229 tan(
PHADJ_ X 2 0.1487 0.0131 tan(
⋅ F)
=− ⋅ F)
at 60Hz
20
0.0155 tan(
PHADJ_ X 2 0.1241 0.009695 tan(
⋅ F)
=− ⋅ F)
at 50Hz
0x15 PHADJ_B 0
0x18 PHADJ_C 0
0x12 L_COMP2_A 16384
The shunt delay compensation is obtained using the equation provided below:
where:
fS = sampling frequency
f = mains frequency
0x15 L_COMP2_B 16384
0x18 L_COMP2_C 16384
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Figure 17. CE Data Flow—Multiplexer and ADC
Figure 18. CE Data Flow—Offset, Gain, and Phase Compensation
OFFSET
NULL
CAL_IA
PHASE
COMP LPF W0
LPF VAR0
90°
I0
PHADJ_0
F0
IA_RAW
OFFSET
NULL
CAL_VA
V0
GAIN_ADJ
F0
VA_RAW
F0
F0
GENERATOR
...OTHER PHASES
DECIMATOR
DE-MULTIPLEXER
∆∑
MOD
VREF
FS = 2184H
zF
S = 2184Hz
IB
MULTIPLEXER
VB
IC
VC
ID
IA
VA
IB_RAW
VB_RAW
IC_RAW
VC_RAW
ID_RAW
IA_RAW
VA_RAW
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Figure 19. CE Data Flow—Squaring and Summation
Ordering Information
F = Lead(Pb)-free/RoHS-compliant package.
R = Tape and reel.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PART TEMP RANGE ACCURACY (typ, %) FLASH (KB) PIN-PACKAGE
71M6545T-IGT/F -40°C to +85°C 0.1 64 64 LQFP
71M6545T-IGTR/F -40°C to +85°C 0.1 64 64 LQFP
71M6545HT-IGT/F -40°C to +85°C 0.1 64 64 LQFP
71M6545HT-IGTR/F -40°C to +85°C 0.1 64 64 LQFP
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
64 LQFP C64L+7 21-0665 90-0411
∑
WA WASUM_X
WB WBSUM_X
WC WCSUM_X
VARA VARASUM_X
VARB VARBSUM_X
VARC VARCSUM_X
∑
SUM
∑
IASQSUM_X
∑
IASQ
I2
V2
IA
IBSQSUM_XIBSQ
IB ICSQSUM_XICSQ
IC VASQSUM_XVASQ
VA
VBSQSUM_XVBSQ
VB VCSQSUM_XVCSQ
VC IDSQSUM_XIDSQ
ID
F0 F0
SQUARE
MPU
SUM_SAMS = 2184
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Typical Operating Circuit
VV3P3A VV3P3SYS
VBAT_RTC
GNDA GNDD
RAM
REGULATOR
POWER SUPPLY
71M6545T
71M6545HT
TEMPERATURE
SENSOR
VREF
PWR MODE
CONTROL
BATTERY
MONITOR
IADC0
VADC9 (VB)
IADC4
IADC5
VADC8 (VA)
IADC2
IADC3
NEUTRAL
SHUNT CURRENT SENSORS
LOAD
C
B
A
MUX AND ADC
IADC1
VADC10 (VC)
IADC6
IADC7
IN*
IC
IB
IA
RESISTOR DIVIDERS
NOTE: THIS SYSTEM IS
REFERENCED TO NEUTRAL
PULSE TRANSFORMERS
NEUTRAL
71M6xx3
*IN = OPTIONAL NEUTRAL CURRENT
PB
AMR
FLASH
MEMORY
ICE
TX
RX
SERIAL PORTS
TMUX COMPUTE
ENGINE
MPU
RTC
TIMERS
RAM
SPI INTERFACE
RTC
BATTERY
XIN
DIO
VV3P3D
24
XOUT
OSCILLATOR/PLL
DIO, PULSES,
LEDs
32kHz
DIO
I2C OR µWIRE
EEPROM
3.3VDC
PULSES
WPULSE
XPULSE
RPULSE
YPULSE
HOST
SPI_CKI
SPI_DI
SPI_DO
SPI_CSZ
XFER_BUSY
SAG
71M6xx3 71M6xx3
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
71M6545T/71M6545HT Energy Meter ICs
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Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 8/13 Initial release —
1 10/13 Removed “future product” status on 71M6545HT in the Ordering Information table,
updated the VREFErrorspecicationintheElectrical Characteristics 10, 62
2 12/13 Updated the CXL and CXS capacitor values from 10pF and 15pF to 22pF 12, 14
3 3/14
Updated the VREFcoefcientsintheElectrical Characteristics table; removed Note
2 from the EC notes; changed CXS and CXL notes in the Recommended External
Components table
8, 10, 12
4 1/15 Updated the Benets and Features section 1
5 12/15
Added a new Reading the Info Page section, a new Test Port table, a replacement for
Table 13, and removed Table 12; updated Table 11 and Table 19; renumbered tables
10-12 accordingly; corrected land pattern number
35, 47,
52, 54, 55,
58, 64