Quad ADC with Diagnostics
Data Sheet
ADAU1977
Rev. C Document Feedback
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FEATURES
Programmable microphone bias (5 V to 9 V) with diagnostics
Four 10 V rms capable direct-coupled differential inputs
On-chip PLL for master clock
Low EMI design
109 dB ADC dynamic range
−95 dB THD + N
Selectable digital high-pass filter
24-bit ADC with 8 kHz to 192 kHz sample rates
Digital volume control with autoramp function
I2C/SPI control
Software-controllable clickless mute
Software power-down
Right justified, left justified, I2S justified, and TDM modes
Master and slave operation modes
40-lead LFCSP package
Qualified for automotive applications
APPLICATIONS
Automotive audio systems
Active noise cancellation system
GENERAL DESCRIPTION
The ADAU1977 incorporates four high performance analog-to-
digital converters (ADCs) with direct-coupled inputs capable of
10 V rms. The ADC uses multibit sigma-delta (Σ-Δ) architecture
with continuous time front end for low EMI. The ADCs can be
connected to the electret microphone (ECM) directly and pro-
vide the bias for powering the microphone. Built-in diagnostic
circuitry detects faults on input lines and includes comprehensive
diagnostics for faults on microphone inputs. The faults reported
are short to battery, short to microphone bias, short to ground,
short between positive and negative input pins, and open input
terminals. In addition, each diagnostic fault is available as an
IRQ flag for ease in system design. An I2C/SPI control port is
also included. The ADAU1977 uses only a single 3.3 V supply.
The part internally generates the microphone bias voltage. The
microphone bias is programmable in a few steps from 5 V to 9 V.
The low power architecture reduces the power consumption.
An on-chip PLL can derive the master clock from an external
clock input or frame clock (sample rate clock). When fed with
a frame clock, the PLL eliminates the need for a separate high
frequency master clock in the system. The ADAU1977 is
available in a 40-lead LFCSP package.
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
MICBIAS
MB_GND
DIAGNOSTICS
AIN1P
VBOOST_IN
VBOOST_OUT
SCL/CCLK
SDA/COUT
ADDR1/CIN
ADDR0/CLATCH
FAULT
PD/RST
AIN1N
AIN2P
AIN2N
AIN3P
AIN3N
AIN4P
AIN4N
VBAT
AVDDx AVDD2
AGNDx
BG
REF
ATTENUATOR 14dB
PROGRAMM ABLE G AIN
DECIMATOR/HPF
DC CALI BRATION
I2C/SPI
CONTROL
SERIAL AUDIO P ORT
5V TO 9V
PROG
BIAS
SW
VBAT
VREF
MCLKIN
PLL_FILT
AVDD1
AVDD3
AVDD2
DGND
AGND3
AGND2
AGND1
PGND
SA_MODE
PLL
AGND2
PGND
DVDD
IOVDD
LRCLK
BCLK
SDATAOUT1
SDATAOUT2
BOOST
CONVERTER
I
OUT
50mA
3.3V TO 1.8V
REGULATOR
ADAU1977
10296-001
ADC
ADC
ADC
ADC
AGND1
AGND2
AGND3
AVDD1
AVDD3
ADAU1977 Data Sheet
Rev. C | Page 2 of 68
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 3
Specifications ..................................................................................... 4
Analog Performance Specifications ........................................... 4
Diagnostic and Fault Specifications ........................................... 5
Digital Input/Output Specifications........................................... 6
Power Supply Specifications........................................................ 6
Digital Filters Specifications ....................................................... 7
Timing Specifications .................................................................. 8
Absolute Maximum Ratings .......................................................... 10
Thermal Resistance .................................................................... 10
ESD Caution ................................................................................ 10
Pin Configuration and Function Descriptions ........................... 11
Typical Performance Characteristics ........................................... 13
Theory of Operation ...................................................................... 15
Overview ...................................................................................... 15
Power Supply and Voltage Reference ....................................... 15
Power-On Reset Sequence ........................................................ 15
PLL and Clock ............................................................................. 16
DC-to-DC Boost Converter ...................................................... 17
Microphone Bias ......................................................................... 18
Analog Inputs .............................................................................. 18
ADC ............................................................................................. 22
ADC Summing Modes .............................................................. 22
Diagnostics .................................................................................. 23
Serial Audio Data Output Ports—Data Format ..................... 25
Control Ports ................................................................................... 30
I2C Mode ...................................................................................... 31
SPI Mode ..................................................................................... 34
Register Summary .......................................................................... 36
Register Details ............................................................................... 37
Master Power and Soft Reset Register ..................................... 37
PLL Control Register ................................................................. 38
DC-to-DC Boost Converter Control Register ....................... 39
MICBIAS and Boost Control Register .................................... 40
Block Power Control and Serial Port Control Register ......... 41
Serial Port Control Register1 .................................................... 42
Serial Port Control Register2 .................................................... 43
Channel Mapping for Output Serial Ports Register ............... 44
Channel Mapping for Output Serial Ports Register ............... 46
Serial Output Drive and Overtemperature Protection
Control Register ......................................................................... 48
Post ADC Gain Channel 1 Control Register .......................... 49
Post ADC Gain Channel 2 Control Register .......................... 50
Post ADC Gain Channel 3 Control Register .......................... 51
Post ADC Gain Channel 4 Control Register .......................... 52
High-Pass Filter and DC Offset Control Register and
Master Mute ................................................................................ 53
Diagnostics Control Register .................................................... 54
Diagnostics Report Register Channel 1 .................................. 55
Diagnostics Report Register Channel 2 .................................. 56
Diagnostics Report Register Channel 3 .................................. 57
Diagnostics Report Register Channel 4 .................................. 58
Diagnostics Interrupt Pin Control Register 1 ......................... 59
Diagnostics Interrupt Pin Control Register 2 ......................... 60
Diagnostics Adjustments Register 1 ........................................ 61
Diagnostics Adjustments Register 2 ........................................ 62
ADC Clipping Status Register .................................................. 63
Digital DC High-Pass Filter and Calibration Register .......... 64
Applications Circuit ....................................................................... 65
Outline Dimensions ....................................................................... 66
Ordering Guide .......................................................................... 66
Automotive Products ................................................................. 66
Data Sheet ADAU1977
Rev. C | Page 3 of 68
REVISION HISTORY
1/14—Rev. B to Rev. C
Change to Features Section .............................................................. 1
Change to Dynamic Range (A-Weighted) Parameter, Table 1 .... 4
Change to Figure 9 .......................................................................... 13
Change to Figure 36 ........................................................................ 32
Change to Figure 46 ........................................................................ 65
9/13—Rev. A to Rev. B
Changes to Figure 1 .......................................................................... 1
Moved Revision History Section ..................................................... 3
Changes to Figure 14 ...................................................................... 16
Changes to Figure 46 ...................................................................... 65
3/13—Rev. 0 to Rev. A
Changed CP-40-9 to CP-40-14 ......................................... Universal
Changes to Hysteresis AINxP and AINxN Shorted Together
Parameter, Table 2 ............................................................................. 4
Changes to Thermal Resistance Section and Table 8 ................... 9
Changes to SPI Mode Section ....................................................... 32
Changes to Channel Mapping for Output Serial Ports Register
Section and Table 34 ....................................................................... 44
Changes to Figure 46 ...................................................................... 63
Changes to Ordering Guide ........................................................... 64
1/13—Revision 0: Initial Version
ADAU1977 Data Sheet
Rev. C | Page 4 of 68
SPECIFICATIONS
Performance of all channels is identical, exclusive of the interchannel gain mismatch and interchannel phase deviation specifications.
AVDDx/IOVDD = 3.3 V; DVDD (internally generated) = 1.8 V; VBAT = 14.4 V; TA = −40°C to +105°C, unless otherwise noted; master
clock = 12.288 MHz (48 kHz fS, 256 × fS mode); input sample rate = 48 kHz; measurement bandwidth = 20 Hz to 20 kHz; word width =
24 bits; load capacitance (digital output) = 20 pF; load current (digital output) = ±1 mA; digital input voltage high = 2.0 V; digital input
voltage low = 0.8 V.
ANALOG PERFORMANCE SPECIFICATIONS
Table 1.
Parameter Test Conditions/Comments Min Typ Max Unit
LINE INPUT APPLICATION See Figure 46
Full-Scale Differential Input Voltage DC-coupled, VCM at AINxP/AINxN = 7 V 10 V rms
Full-Scale Single-Ended Input Voltage DC-coupled, VCM at AINxP/AINxN = 7 V 5 V rms
MICROPHONE INPUT APPLICATION See Figure 46, MICBIAS = 8.5 V
Differential Input Voltage DC-coupled, VCM at AINxP = 5.66 V, AINxN = 2.83 V 2 V rms
QUASI DC INPUT
Single-Ended Input Voltage 5 V peak
Input Common-Mode Voltage VCM at AINxP/AINxN pins 0 8 V dc
Peak Input Voltage VCM + V ac peak at AINxP/AINxN pins 0 14 V
MICROPHONE BIAS
Output Voltage Programmable from 5 V to 9 V in steps of 0.5 V; the
output voltage is within the specified load
regulation
5 9 V
Load Regulation From no load to maximum load of 25 mA at 5 V −1 +0.2 +1 %
From no load to maximum load of 45 mA at 9 V −1 +0.3 +1 %
Output Current At MICBIAS = 5 V 25 mA
At MICBIAS = 9 V 45 mA
Output Noise 20 Hz to 20 kHz, MICBIAS = 5 V 22 32 µV rms
20 Hz to 20 kHz, MICBIAS = 9 V 35 54 µV rms
Power Supply Rejection Ratio (PSRR) 350 mV rms, 1 kHz ripple on VBOOST_IN at 10 V 60 dB
Interchannel Isolation at MICBIAS Pin Referred to full scale at 1 kHz 60 dB
Start-Up Time With CLOAD = 1 nF 40 ms
BOOST CONVERTER
Input Voltage 2.97 3.3 3.63 V
Input Current L = 4.7 µH, fSW = 1.536 MHz, MICBIAS = 9 V at 45 mA load 195 mA
L = 2.2 µH, fSW = 3.072 MHz, MICBIAS = 9 V at 45 mA load 220 mA
Output Current MICBIAS = 5 V 50 mA
MICBIAS = 9 V 88 mA
Load Regulation From no load to maximum load of 50 mA at MICBIAS
= 5 V
−1 +1 %
From no load to maximum load of 88 mA at MICBIAS
= 9 V
−1 +1 %
Input Overcurrent Threshold 900 mA peak
Switching Frequency fS = 48 kHz L = 2.2 µH 3.072 MHz
fS = 48 kHz, L = 4.7 µH 1.536 MHz
External Load Capacitor at VBOOST_OUT Pin 4.7 10 22 µF
ANALOG-TO-DIGITAL CONVERTERS
Input Resistance
Differential Between AINxP and AINxN 50 kΩ
Single-Ended (Rin1977) Between AINxP and AINxN 25 kΩ
ADC Resolution 24 Bits
Dynamic Range (A-Weighted)1 Input = 1 kHz, −60 dBFS
Line Input Referred to full-scale differential input = 10 V rms 103 109 dB
Microphone Input Referred to full-scale differential input = 2 V rms 95 dB
Total Harmonic Distortion Plus Noise
(THD + N)
Input = 1 kHz, −1 dBFS (0 dBFS = 10 V rms input) −95 −89 dB
Data Sheet ADAU1977
Rev. C | Page 5 of 68
Parameter Test Conditions/Comments Min Typ Max Unit
Digital Gain Post ADC Gain step size = 0.375 dB −35.625 +60 dB
Gain Error −10 +10 %
Interchannel Gain Mismatch −0.25 +0.25 dB
Gain Drift 0.6 ppm/°C
Common-Mode Rejection Ratio (CMRR) 1 V rms, 1 kHz 60 dB
1 V rms, 20 kHz 56 dB
Power Supply Rejection Ratio (PSRR) 100 mV rms, 1 kHz on AVDDx = 3.3 V 70 dB
Interchannel Isolation 100 dB
Interchannel Phase Deviation 0 Degrees
REFERENCE
Internal Reference Voltage VREF pin 1.47 1.50 1.54 V
Output Impedance 20 kΩ
ADC SERIAL PORT
Output Sample Rate 8 192 kHz
1 For fS ranging from 44.1 kHz to 192 kHz.
DIAGNOSTIC AND FAULT SPECIFICATIONS
Applicable to differential microphone input using MICBIAS on AINxP and AINxN pins.
Table 2.
Parameter
Test Conditions/
Comments Min Typ Max Unit
INPUT VOLTAGE THRESHOLDS FOR FAULT DETECTION1
Hysteresis AINxP or AINxN Shorted to VBAT
SHT_B_TRIP = 10
0.79 × VBAT
0.85 × VBAT
0.86 × VBAT
V
SHT_B_TRIP = 01 0.84 × VBAT 0.9 × VBAT 0.91 × VBAT V
SHT_B_TRIP = 00 0.89 × VBAT 0.95 × VBAT 0.96 × VBAT V
SHT_B_TRIP = 11 0.93 × VBAT 0.975 × VBAT 0.99 × VBAT V
Hysteresis AINxP and AINxN Shorted Together SHT_T_TRIP = 00 MICBIAS(0.5 ± 0.015) MICBIAS(0.5 ±
0.035)
MICBIAS(0.5 ±
0.047)
V
SHT_T_TRIP = 01 MICBIAS(0.5 ± 0.001) MICBIAS(0.5 ±
0.017)
MICBIAS(0.5 ±
0.03)
V
SHT_T_TRIP = 10 MICBIAS(0.5 ± 0.05) MICBIAS(0.5 ±
0.071)
MICBIAS(0.5 ±
0.08)
V
Hysteresis AINxP or AINxN Shorted to Ground SHT_G_TRIP = 10 0.04 × VREF 0.1 × VREF 0.13 × VREF V
SHT_G_TRIP = 01 0.08 × VREF 0.133 × VREF 0.16 × VREF V
SHT_G_TRIP = 00 0.12 × VREF 0.2 × VREF 0.22 × VREF V
SHT_G_TRIP = 11 0.19 × VREF 0.266 × VREF 0.28 × VREF V
Hysteresis AINxP Shorted to MICBIAS SHT_M_TRIP = 10 0.82 × MICBIAS 0.85 × MICBIAS 0.89 × MICBIAS V
SHT_M_TRIP = 01 0.87 × MICBIAS 0.9 × MICBIAS 0.94 × MICBIAS V
SHT_M_TRIP = 00 0.92 × MICBIAS 0.95 × MICBIAS 1.0 × MICBIAS V
SHT_M_TRIP = 11 0.95 × MICBIAS 0.975 × MICBIAS 1.0 × MICBIAS V
Hysteresis AINxP or AINxN Open Circuit2 Refer to the
AINxP shorted to
MICBIAS and the
AINxN shorted
to ground
specifications for
upper and lower
thresholds.
FAULT DURATION Programmable 10 100 150 ms
1 The threshold limits are tested with VREF = 1.5 V, MICBIAS = 5 V to 8.5 V, and VBAT = 11 V to 18 V set using an external source. When VBAT ≤ MICBIAS, a short to VBAT
cannot be distinguished from a short to MICBIAS, and reporting a short to VBAT fault takes precedence over a short to MICBIAS fault.
2 The AINxP open terminal fault cannot be distinguished from the AINxN open terminal fault because the voltage at the AINxP and AINxN pins remain at MICBIAS and
ground, respectively, when either of these two terminals becomes open circuit.
ADAU1977 Data Sheet
Rev. C | Page 6 of 68
DIGITAL INPUT/OUTPUT SPECIFICATIONS
Table 3.
Parameter Test Conditions/Comments Min Max Unit
INPUT
High Level Input Voltage (VIH) 0.7 × IOVDD V
Low Level Input Voltage (VIL) 0.3 × IOVDD V
Input Leakage Current ±10 µA
Input Capacitance 5 pF
OUTPUT
High Level Output Voltage (V
OH
)
I
OH
= 1 mA
IOVDD − 0.60
V
Low Level Output Voltage (VOL) IOL = 1 mA 0.4 V
POWER SUPPLY SPECIFICATIONS
L = 4.7 µH, AVDDx = 3.3 V, DVDD = 1.8 V, IOVDD = 3.3 V, fS = 48 kHz (master mode), unless otherwise noted.
Table 4.
Parameter Test Conditions/Comments Min Typ Max Unit
DVDD On-chip LDO 1.62 1.8 1.98 V
AVDDx 3.0 3.3 3.6 V
IOVDD 1.62 3.3 3.6 V
VBAT 1 14.4 18 V
IOVDD Current Master clock = 256 fS
Normal Operation fS = 48 kHz 450 µA
fS = 96 kHz 880 µA
fS = 192 kHz 1.75 mA
Power-Down fS = 48 kHz to 192 kHz 20 µA
AVDDx Current
Normal Operation Boost off, 4-channel ADC, DVDD internal 14 mA
Boost on, 4-channel ADC, DVDD internal 14.5 mA
Boost off, 4-channel ADC, DVDD external 9.6 mA
Boost on, 4-channel ADC, DVDD external 10.1 mA
Power-Down 270 µA
Boost Converter Current
Normal Operation Boost on, 4-channel ADC, MICBIAS = 8.5 V, no load 34 mA
Boost on, 4-channel ADC, MICBIAS = 8.5 V, 42 mA 168 mA
Power-Down 180 µA
DVDD Current
Normal Operation DVDD external = 1.8 V 4.5 mA
Power-Down 65 µA
VBAT Current VBAT = 14.4 V
Normal Operation 575 625 µA
Power-Down 575 625 µA
POWER DISSIPATION
Normal Operation Master clock = 256 fS, 48 kHz
AVDDx DVDD internal, MICBIAS = 8.5 V at 42 mA load 265 mW
Power-Down, All Supplies PD/RST pin held low 9 mW
1 When VBAT ≤ MICBIAS, a short to VBAT cannot be distinguished from a short to MICBIAS, and reporting a short to VBAT fault takes precedence over a short to MICBIAS fault.
Data Sheet ADAU1977
Rev. C | Page 7 of 68
DIGITAL FILTERS SPECIFICATIONS
Table 5.
Parameter Mode Factor Min Typ Max Unit
ADC DECIMATION FILTER
All modes, typical at f
S
= 48 kHz
Pass Band 0.4375 × fS 21 kHz
Pass-Band Ripple ±0.015 dB
Transition Band 0.5 × fS 24 kHz
Stop Band 0.5625 × fS 27 kHz
Stop-Band Attenuation
79
dB
Group Delay fS = 8 kHz to 96 kHz 22.9844/fS 479 µs
fS = 192 kHz 35 µs
HIGH-PASS FILTER
All modes, typical at 48 kHz
Cutoff Frequency At −3 dB point 0.9375 Hz
Phase Deviation At 20 Hz 10 Degrees
Settling Time
ADC DIGITAL GAIN All modes 0 60 dB
Gain Step Size 0.375 dB
ADAU1977 Data Sheet
Rev. C | Page 8 of 68
TIMING SPECIFICATIONS
Table 6.
Limit at
Parameter Min Max Unit Description
INPUT MASTER CLOCK (MCLK)
Duty Cycle 40 60 % MCLKIN duty cycle; MCLKIN at 256 × fS, 384 × fS, 512 × fS, and 768 × fS
fMCLK See Table 10 MHz MCLKIN frequency, PLL in MCLK mode
RESET
Reset Pulse 15 ns RST low
PLL
Lock Time 10 ms
I2C PORT
fSCL 400 kHz SCL frequency
tSCLH 0.6 µs SCL high
tSCLL 1.3 µs SCL low
tSCS 0.6 µs Setup time; relevant for repeated start condition
tSCH 0.6 µs Hold time; after this period of time, the first clock pulse is generated
tDS 100 ns Data setup time
tDH 0 Data hold time
tSCR 300 ns SCL rise time
tSCF 300 ns SCL fall time
t
SDR
300
ns
SDA rise time
tSDF 300 ns SDA fall time
tBFT 1.3 µs Bus-free time; time between stop and start
tSUSTO 0.6 µs Setup time for stop condition
SPI PORT
tCCPH 35 ns CCLK high
tCCPL 35 ns CCLK low
fCCLK 10 MHz CCLK frequency
tCDS 10 ns CIN setup to CCLK rising
tCDH 10 ns CIN hold from CCLK rising
tCLS 10 ns CLATCH setup to CCLK rising
tCLH 40 ns CLATCH hold from CCLK rising
tCLPH 10 ns CLATCH high
tCOE 30 ns COUT enable from CLATCH falling
t
COD
30
ns
COUT delay from CCLK falling
tCOTS 30 ns COUT tristate from CLATCH rising
ADC SERIAL PORT
t
ABH
10
ns
BCLK high, slave mode
tABL 10 ns BCLK low, slave mode
tALS 10 ns LRCLK setup to BCLK rising, slave mode
tALH 5 ns LRCLK hold from BCLK rising, slave mode
tABDD 18 ns SDATAOUTx delay from BCLK falling
Data Sheet ADAU1977
Rev. C | Page 9 of 68
Figure 2. Serial Output Port Timing
Figure 3. SPI Port Timing
Figure 4. I2C Port Timing
BCLK
LRCLK
SDATAOUTx
LEFT JUSTIFIED
MODE
SDATAOUTx
RIGHT JUSTIFIED
MODE
LSB
SDATAOUTx
I
2
S MODE
MSB MSB – 1
MSB
MSB
8-BI T CLOCKS
(24-BIT DATA)
12-BI T CLOCKS
(20-BIT DATA)
14-BI T CLOCKS
(18-BIT DATA)
16-BI T CLOCKS
(16-BIT DATA)
tABL
tABDD
tABDD
tABH
tABDD
t
ALS
tALH
10296-002
CLATCH
CCLK
CIN
COUT
tCLS
tCDS
tCDH
tCOD
tCCPH
tCCPL
tCLH tCLPH
tCOE
tCOTS
10296-003
t
SCH
t
SCLH
t
SCR
t
SCLL
t
SCF
SDA
SCL
t
SCH
t
SCS
t
DH
t
SDF
t
SDR
t
DS
STOP START
t
SUSTO
t
BFT
10296-004
ADAU1977 Data Sheet
Rev. C | Page 10 of 68
ABSOLUTE MAXIMUM RATINGS
Table 7.
Parameter Rating
Analog Supply (AVDDx) −0.3 V to +3.63 V
Digital Supply
DVDD −0.3 V to +1.98 V
IOVDD −0.3 V to +3.63 V
Input Current (Except Supply Pins) ±20 mA
Analog Input Voltage (AINx, VBAT Pins) −0.3 V to +18 V
Digital Input Voltage (Signal Pins) −0.3 V to +3.63 V
Operating Temperature Range (Ambient)
−40°C to +105°C
Junction Temperature Range −40°C to +125°C
Storage Temperature Range −65°C to +150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
θJA represents thermal resistance, junction-to-ambient, and θJC
represents the thermal resistance, junction-to-case. All
characteristics are for a standard JEDEC board per JESD51.
Table 8. Thermal Resistance
Package Type θJA θJC Unit
40-Lead LFCSP 32.8 1.93 °C/W
ESD CAUTION
Data Sheet ADAU1977
Rev. C | Page 11 of 68
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 5. Pin Configuration, 40-Lead LFCSP
Table 9. Pin Function Descriptions
Pin No. Mnemonic In/Out1 Description
1 AGND1 P Analog Ground.
2 VREF O Voltage Reference. Decouple this pin to AGNDx with 10 µF||100 nF capacitors.
3
PLL_FILT
O
PLL Loop Filter. Return this pin to AVDDx using recommended loop filter components.
4 AVDD2 P Analog Power Supply. Connect this pin to analog 3.3 V supply.
5 AGND2 P Analog Ground.
6 PD/ RST I Power-Down Reset (Active Low).
7 MCLKIN I Master Clock Input.
8 FAULT O Fault Output. Programmable logic output.
9 SA_MODE I Standalone Mode. Connect this pin to IOVDD using a 10 kΩ pull-up resistor for standalone mode.
10 DVDD O 1.8 V Digital Power Supply Output. Decouple this pin to DGND with a 0.1 µF capacitor.
11
DGND
P
Digital Ground.
12 IOVDD P Digital Input and Output Power Supply. Connect this pin to a supply in the range of 1.8 V to 3.3 V.
13 SDATAOUT1 O ADC Serial Data Output Pair 1.
14 SDATAOUT2 O ADC Serial Data Output Pair 2.
15 LRCLK I/O Frame Clock for the ADC Serial Port.
16 BCLK I/O Bit Clock for the ADC Serial Port.
17 SDA/COUT I/O Serial Data Output I2C/Control Data Output (SPI).
18 SCL/CCLK I Serial Clock Input I2C/Control Clock Input (SPI).
19 ADDR0/CLATCH I Chip Address Bit 0 Setting I2C/Chip Select Input for Control Data (SPI).
20 ADDR1/CIN I Chip Address Bit 1 Setting I2C/Control Data Input (SPI).
21 PGND P Power Ground Boost Converter.
22
PGND
P
Power Ground Boost Converter.
23 SW I Inductor Switching Terminal.
24 SW I Inductor Switching Terminal.
25 VBOOST_OUT O Boost Converter Output. Decouple this pin to PGND with a 10 µF capacitor.
26 VBOOST_IN I MICBIAS Regulator Input. Connect this pin to VBOOST_OUT (Pin 25).
27 MICBIAS O Microphone Bias Output. Decouple this pin to AGNDx using a 10 µF capacitor.
28 MB_GND P Analog Return Ground for the Microphone Bias Regulator. Connect this pin directly to AGNDx
for best noise performance.
29 AGND3 P Analog Ground.
30 VBAT I Voltage Sense for Diagnostics. Connect this pin to a load dump suppressed battery voltage.
Decouple this to AGNDx using a 0.1 µF capacitor.
PIN 1
INDICATOR
1AGND1 2
VREF 3
PLL_FILT4
AVDD2 5
AGND2 6
PD/RST 7
MCLKIN 8
FAULT 9
SA_MODE
NOTES
1. THE EXPOSED PAD M US T BE CONNECTED TO THE GRO UND P LANE ON T HE P CB.
10DVDD
23 SW
24 SW
25 VBOOST_OUT
26 VBOOST_IN
27 MICBIAS
28 MB_GND
29 AGND3
30 VBAT
22 PGND
21 PGND
11DGND 12IOVDD 13SDATAOUT1
15LRCLK
17SDA/COUT 16BCLK
18SCL/CCLK 19
ADDR0/CLATCH 20ADDR1/CIN
14SDATAOUT2
33 AIN1P
34 AIN2N
35 AIN2P
36 AIN3N
37 AIN3P
38 AIN4N
39 AIN4P
40 AVDD1
32 AIN1N
31 AVDD3
TOP VIEW
(No t t o Scal e)
ADAU1977
10296-005
ADAU1977 Data Sheet
Rev. C | Page 12 of 68
Pin No. Mnemonic In/Out1 Description
31 AVDD3 P Analog Power Supply. Connect this pin to an analog 3.3 V supply.
32 AIN1N I Analog Input Channel 1 Inverting Input.
33 AIN1P I Analog Input Channel 1 Noninverting Input.
34 AIN2N I Analog Input Channel 2 Inverting Input.
35 AIN2P I Analog Input Channel 2 Noninverting Input.
36 AIN3N I Analog Input Channel 3 Inverting Input.
37 AIN3P I Analog Input Channel 3 Noninverting Input.
38 AIN4N I Analog Input Channel 4 Inverting Input.
39 AIN4P I Analog Input Channel 4 Noninverting Input.
40 AVDD1 P Analog Power Supply. Connect this pin to an analog 3.3 V supply.
EP Exposed Pad. The exposed pad must be connected to the ground plane on the printed circuit
board (PCB).
1 I = input, O = output, I/O = input/output, and P = power.
Data Sheet ADAU1977
Rev. C | Page 13 of 68
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 6. Fast Fourier Transform, 2 mV Differential Input at fS = 48 kHz
Figure 7. Fast Fourier Transform, −1 dBFS Differential Input
Figure 8. THD + N vs. Input Amplitude
Figure 9. CMRR Differential Input, Referenced to 1 V Differential Input
Figure 10. Fast Fourier Transform, No Input
Figure 11. ADC Pass-Band Ripple at fS = 48 kHz
20 204 6 8 10 12 14 16 18
–160
0
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
FREQUENCY (kHz)
AMPLITUDE (dBFS)
10296-006
20 204 6 8 10 12 14 16 18
FREQUENCY (kHz)
AMPLITUDE (dBFS)
–160
0
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
10296-007
0 2 12
4 6
INPUT AMPL IT UDE ( V rms)
THD + N ( dB)
810
–160
0
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
10296-008
–100
0
–95
–90
–85
–80
–75
–70
–65
–60
–55
–50
–45
–40
–35
–30
–25
–20
–15
–10
–5
20 20k
100 1k
CMRR (dB)
FREQUENCY (Hz) 10k
10296-009
0 2 20
4 6 8 10 12 14 16 18
FREQUENCY (kHz)
AMPLITUDE (dBFS)
–160
0
–150
–140
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
10296-010
0.10
0.08
0.06
0.04
0.02
0
–0.10
–0.08
–0.06
–0.04
–0.02
018000160001400012000100008000600040002000
MAG NITUDE ( dB)
FRE QUENCY ( Hz )
10296-011
ADAU1977 Data Sheet
Rev. C | Page 14 of 68
Figure 12. ADC Filter Stop-Band Response at fS = 48 kHz
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100 0400005000 10000 15000 20000 25000 30000 35000
MAG NITUDE ( dB)
FRE QUENCY ( Hz )
10296-012
Data Sheet ADAU1977
Rev. C | Page 15 of 68
THEORY OF OPERATION
OVERVIEW
The ADAU1977 incorporates four high performance ADCs
with an integrated boost converter for microphone bias, the
associated microphone diagnostics for fault detection, and a
phase-locked loop circuit for generating the necessary on-chip
clock signals.
POWER SUPPLY AND VOLTAGE REFERENCE
The ADAU1977 requires a single 3.3 V power supply. Separate
power supply input pins are provided for the analog and boost
converter. These pins should be decoupled to AGND with 100 nF
ceramic chip capacitors placed as close as possible to the pins to
minimize noise pickup. A bulk aluminum electrolytic capacitor
of at least 10 μF must be provided on the same PCB as the ADC.
It is important that the analog supply be as clean as possible for
best performance.
The supply voltage for the digital core (DVDD) is generated
using an internal low dropout regulator. The typical DVDD
output is 1.8 V and must be decoupled using a 100 nF ceramic
capacitor and a 10 µF capacitor. Place the 100 nF ceramic
capacitor as close as possible to the DVDD pin.
The voltage reference for the analog blocks is generated
internally and output at the VREF pin (Pin 2). The typical
voltage at the pin is 1.5 V with an AVDDx of 3.3 V.
All digital inputs are compatible with TTL and CMOS levels.
All outputs are driven from the IOVDD supply. The IOVDD
can be in the range of 1.8 V to 3.3 V. The IOVDD pin must
be decoupled with a 100 nF capacitor placed as close to the
IOVDD pin as possible. It is recommended to connect the
AGND, DGND, PGND, and exposed pad to a single GND
plane on the PCB for best performance.
The ADC internal voltage reference is output from the VREF pin
and should be decoupled using a 100 nF ceramic capacitor in
parallel with a 10 μF capacitor. The VREF pin has limited
current capability. The voltage reference is used as a reference to
the ADC; therefore, it is recommended not to draw current
from this pin for external circuits. When using this reference,
use a noninverting amplifier buffer to provide a reference to
other circuits in the application.
In reset mode, the VREF pin is disabled to save power and is
enabled only when the RST pin is pulled high.
POWER-ON RESET SEQUENCE
The ADAU1977 requires that a single 3.3 V power supply be
provided externally at the AVDDx pin. The part internally generates
DVDD (1.8 V), which is used for the digital core of the ADC.
The DVDD supply output pin (Pin 10) is provided to connect
the decoupling capacitors to DGND. The typical recommended
values for the decoupling capacitors are 100 nF in parallel with
10 µF. During a reset, the DVDD regulator is disabled to reduce
power consumption. After the PD/RST pin (Pin 6) is pulled high,
the part enables the DVDD regulator. However, the internal ADC
and digital core reset is controlled by the internal POR signal
(power-on reset) circuit, which monitors the DVDD level.
Therefore, the device does not come out of a reset until DVDD
reaches 1.2 V and the POR signal is released. The DVDD settling
time depends on the charge-up time for the external capacitors
and on the AVDDx ramp-up time.
The internal POR circuit is provided with hysteresis to ensure
that a reset of the part is not initiated by an instantaneous glitch
on DVDD. The typical trip points are 1.2 V with RST high and
0.6 V (±20%) with RST low. This ensures that the core is not
reset until the DVDD level falls below the 0.6 V trip point.
As soon as the PD/RST pin is pulled high, the internal regulator
starts charging up the CEXT on the DVDD pin. The DVDD charge-
up time is based on the output resistance of the regulator and
the external decoupling capacitor. The time constant can be
calculated as
tC = ROUT × CEXT (ROUT = 20 Ω typical)
For example, if CEXT is 10 µF, then tC is 200 µs and is the time to
reach the DVDD voltage, within 63.6%.
The POR circuit releases an internal reset of the core when DVDD
reaches 1.2 V (see Figure 13). Therefore, it is recommended to
wait for at least the tC period to elapse before sending I2C or SPI
control signals.
Figure 13. Power-On Reset Timing
When applying a hardware reset to the part by pulling the
PD/RST pin (Pin 6) low and then high, there are certain time
restrictions. During the RST low pulse period, the DVDD starts
discharging. The discharge time constant is decided by the internal
resistance of the regulator and CEXT. The time required for DVDD
to fall from 1.8 V to 0.48 V (0.6 V − 20%) can be estimated using
the following equation:
tD = 1.32 × RINT × CEXT
where RINT = 64 kΩ typical. (RINT can vary due to process by ±20%.)
For example, if CEXT is 10 µF, then tD is 0.845 sec.
1.2V
0.48V
POR
DVDD (1.8V)
PD/RST
AVDDx
t
RESET
t
D
t
C
10296-013
ADAU1977 Data Sheet
Rev. C | Page 16 of 68
Depending on CEXT, tD may vary and in turn decide the minimum
hold period for the RST pulse. The RST pulse must be held low
for the tD time period to initialize the core properly.
The required RST low pulse period can be reduced by adding a
resistor across CEXT. The new tD value can then be calculated as
tD = 1.32 × REQ × CEXT
where REQ = 64 kΩ || REXT.
The resistor ensures that DVDD not only discharges quickly during
a reset or an AVDDx power loss but also resets the internal blocks
correctly. Note that some power loss in this resistor is to be
expected because the resistor constantly draws current from
DVDD. The typical value for CEXT is 10 µF and for REXT is 3 kΩ.
This results in a time constant of
tD = 1.32 × REQ × CEXT = 37.8 ms
where REQ = 2.866 kΩ (64 kΩ || 3 kΩ).
Using this equation at a set CEXT value, the REXT can be
calculated for a desired RST pulse period.
There is also a software reset register (S_RST, Bit 7 of Register 0x00)
available that can be used to reset the part, but it must be noted
that during an AVDDx power loss, the software reset may not
ensure proper initialization because DVDD may not be stable.
Figure 14. DVDD Regulator Output Connections
PLL AND CLOCK
The ADAU1977 has a built-in analog PLL to provide a jitter-
free master clock to the internal ADC. The PLL must be
programmed for the appropriate input clock frequency. The
PLL Control Register 0x01 is used for setting the PLL.
The CLK_S bit (Bit 4) of Register 0x01 is used for setting the
clock source for the PLL. The clock source can be either the
MCLKIN pin or the LRCLK pin (slave mode). In LRCLK mode,
the PLL can support sample rates between 32 kHz and 192 kHz.
In MCLK input mode, the MCS bits (Bits[2:0] of Register 0x01)
must be set to the desired input clock frequency for the MCLKIN
pin. Table 10 shows the input MCLK required for the most
common sample rates and the MCS bit settings.
The PLL_LOCK bit (Bit 7) of Register 0x01 indicates the lock
status of the PLL. It is recommended that after initial power-up
the PLL lock status be read to ensure that the PLL outputs the
correct frequency before unmuting the audio outputs.
Table 10. Required Input MCLK for Common Sample Rates
MCS
(Bits[2:0]) fS (kHz)
Frequency Multi-
plication Ratio
MCLKIN Frequency
(MHz)
000 32 128 × fS 4.096
001 32 256 × fS 8.192
010 32 384 × fS 12.288
011 32 512 × fS 16.384
100 32 768 × fS 24.576
000 44.1 128 × fS 5.6448
001 44.1 256 × fS 11.2896
010 44.1 384 × fS 16.9344
011 44.1 512 × fS 22.5792
100 44.1 768 × fS 33.8688
000
48
128 × f
S
6.144
001 48 256 × fS 12.288
010 48 384 × fS 18.432
011 48 512 × fS 24.576
100 48 768 × fS 36.864
000 96 64 × fS 6.144
001 96 128 × fS 12.288
010 96 192 × fS 18.432
011 96 256 × fS 24.576
100 96 384 × fS 36.864
000 192 32 × fS 6.144
001
192
64 × f
S
12.288
010 192 96 × fS 18.432
011 192 128 × fS 24.576
100 192 192 × fS 36.864
The PLL can accept the audio frame clock (sample rate clock) as
input, but the serial port must be configured as a slave and the
frame clock must be fed to the part from the master. It is strongly
recommended that the PLL be disabled, reprogrammed with the
new setting, and then reenabled. A lock bit is provided that can be
polled via the I2C to check whether the PLL has acquired lock.
The PLL requires an external filter, which is connected at the
PLL_FILT pin (Pin 3). The recommended PLL filter circuit for
MCLK or LRCLK mode is shown in Figure 15. Using NPO
capacitors is recommended for temperature stability. Place the
filter components close to the device for best performance.
Figure 15. PLL Filter
3.3V TO 1.8V
REGULATOR
DVDD
ADAU1977
IOVDD
+1.8V OR +3.3V
C
0.1µF
C
0.1µF
C
EXT
10µF
ML CC X 7R
R
EXT
3kΩ
AVDD1 AVDD3 AVDD2
+3.3V
TO INTERNAL
BLOCKS
10296-114
AVDDx
PLL_LF
LRCLK MO DE
39nF
4.87kΩ
2.2nF
AVDDx
PLL_LF
MCL K M ODE
5.6nF
1kΩ
390pF
10296-014
Data Sheet ADAU1977
Rev. C | Page 17 of 68
DC-TO-DC BOOST CONVERTER
The boost converter generates a supply voltage for the
microphone bias circuit from a fixed 3.3 V supply. The boost
converter output voltage is programmable using Register 0x03.
The boost converter output voltage is approximately 1 V above
the set microphone bias voltage. The boost converter uses the
clock from the PLL, and the switching frequency is dependent
on the sample rate of the ADC. The FS_RATE bits (Bits[6:5] of
Register 0x02) must be set to the desired sample rate. The boost
converter switching frequency can be selected to be 1.5 MHz or
3 MHz using Bit 4 of Register 0x02. For the 1.5 MHz switching
frequency, the recommended value for the inductor is 4.7 µH,
whereas for the 3 MHz switching frequency, the recommended
value for the inductor is 2.2 µH.
Table 11 lists the typical switching frequency based on the
sample rates.
Capacitor Selection
The boost converter output is available at the VBOOST_OUT pin
(Pin 25) and must be decoupled to PGND using a 10 µF ceramic
capacitor to remove the ripple at the switching frequency. The
capacitor must have low ESR and good temperature stability.
The MLCC X7R/NPO dielectric type with 25 V is recommended.
Care must be taken to place this capacitor as close as possible to
the VBOOST_OUT pin (Pin 25).
Table 11. Typical Switching Frequency Based on the Sample Rates
Boost Converter Switching Frequency
Base Sample Rate (kHz) Sample Rates (kHz) Inductor = 2.2 µH Inductor = 4.7 µH
32 8/16/32/64 (1024/12) × fS (1024/22) × fS
44.1 11.025/22.05/44.1/88.2/176.4 (1024/16) × fS (1024/30) × fS
48 12/24/48/96/192 (1024/16) × fS (1024/32) × fS
ADAU1977 Data Sheet
Rev. C | Page 18 of 68
MICROPHONE BIAS
The microphone bias is generated by the input voltage at the
VBOOST_IN pin (Pin 26) via a linear regulator to ensure low
noise performance and to reject the high frequency noise from
the boost converter. If the internal boost converter output is
used, the VBOOST_OUT pin (Pin 25) must be connected to
the VBOOST_IN pin (Pin 26). If an external supply is used for
the microphone bias, the supply can be fed at the VBOOST_IN
pin (Pin 26); in this case, leave the VBOOST_OUT pin (Pin 25)
open. The microphone bias voltage is programmable from 5 V
to 9 V by using the MB_VOLTS bits (Bits[7:4] of Register 0x03).
The microphone bias output voltage is available at the MICBIAS pin
(Pin 27). This pin can be decoupled to AGND using a maximum of
up to a 10 µF capacitor with an ESR of at least 1 Ω. For higher
value capacitors, especially those above 1 nF, the ESR of the capa-
citor should be ≥ 1 Ω to ensure the stability of the microphone
bias regulator. Register 0x03 can be used to enable the microphone
bias. Table 11 lists the switching frequency of the boost converter
based on the inductor value and common sample rates.
ANALOG INPUTS
The ADAU1977 has four differential analog inputs. The ADCs
can accommodate both dc- and ac-coupled input signals.
The block diagram shown in Figure 16 represents the typical
input circuit.
In most audio applications, the dc content of the signal is removed
by using a coupling capacitor. However, the ADAU1977 consists
of a unique input structure that allows direct coupling of the
input signal, eliminating the need for using a large coupling
capacitor at the input. Each input has a fixed 14 dB attenuator
connected to AGND for accommodating a 10 V rms differential
input. The typical input resistance is approximately 26 kΩ from
each input to AGND.
In dc-coupled applications, if the VCM at AINxP and AINxN is
the same, the dc content in the ADC output is close to 0. If the
input pins are presented with different common-mode dc levels,
the difference between the two levels appears at the ADC output
and can be removed by enabling the high-pass filter.
The high-pass filter has a 1.4 Hz, 6 dB per octave cutoff at a
48 kHz sample rate. The cutoff frequency scales directly with
the sample frequency. However, care is required in dc-coupled
applications to ensure that the common-mode dc voltage does
not exceed the specified limit. The common-mode loop can
accommodate a common-mode dc voltage from 0 V to 7 V. The
input required for the full-scale ADC output (0 dBFS) is typically
10 V rms differential.
Figure 16. Analog Input Block
V
REF
V
X
V
Y
2R
AINxP
AINxN
V
ID
= V INPUT DIFFERENTIAL
V
ICM+
= V
CM
AT AINx+
V
ICM–
= V
CM
AT AINx–
R
2R
R
R
R
R
R
10296-015
Data Sheet ADAU1977
Rev. C | Page 19 of 68
Line Inputs
This section describes some of the possible ways to connect the
ADAU1977 for line level inputs.
Line Input Balanced or Differential Input DC-Coupled Case
For example, in the case of a typical power amplifier for an auto-
mobile, the output can swing around 10 V rms differential with
approximately 7.2 V common-mode dc input voltage (assuming
a 14.4 V battery and bridge-tied load connection). The signal at
each input pin has a 5 V rms or 14.14 V p-p signal swing. With
a common-mode dc voltage of 7.2 V, the signal can swing between
(7.2 V + 7.07 V) = +14.27 V p-p and (7 V − 7.07 V) = 0.13 V at
each input. Therefore, this results in approximately a 28.54 V p-p
differential signal swing and measures around −0.16 dBFS (ac
only with dc high-pass filter) at the ADC output. See Figure 17.
Line Input Balanced or Differential Input AC-Coupled Case
For an amplifier output case with ac coupling, refer to Figure 18
for information about connecting the line level inputs to the
ADAU1977. In this case, the AINxP/AINxN pins must be
pulled up to the required common-mode level using the
resistors on MICBIAS. The VCM must be such that the input
never swings below a ground. In other words, if the input signal
is 14 V p-p, the VCM must be around 14 V/2 = 7 V to ensure that
the signal never swings below a ground. The microphone bias
can provide the required clean reference for generating the VCM.
The R1 value can be calculated as follows:
R1 = Rin1977 (MB − VCM)/VCM
where:
VCM is the peak-to-peak input swing divided by 2.
MB = 8.5 V.
Rin1977 is the single-ended input resistance (see Table 1).
However, in this case the equivalent input resistance of AINxP/
AINxN is reduced and can be calculated as R1 || Rin1977.
Input Resistance = R1 × Rin1977/(R1 + Rin1977)
where Rin1977 is the single-ended value from Table 1.
The C1 and C2 values can be determined for the required low
frequency cutoff using the following equation:
C1 or C2 = 1/(2 × π × fC × Input Resistance)
Line Input Unbalanced or Single-Ended Pseudo Differential
AC-Coupled Case
For a single-ended application, the signal swing is reduced by half
because only one input is used for the signal, and the other input is
connected to 0 V. As a result, the input signal capability is reduced
to 5 V rms in a single-ended application. With a common-mode dc
voltage of 7.2 V, the signal can swing between (7.2 V + 7.07 V)
= +14.27 V p-p and (7.2 V − 7 V) = 0.13 V. Therefore, this
results in approximately a 14.14 V p-p differential signal swing
and measures around −6.16 dBFS (ac only with dc high-pass
filter) at the ADC output. See Figure 19.
The values of the resistors (R1/R2) and capacitors (C1/C2) are
similar to those for the balanced ac-coupled case described in
the Line Input Balanced or Differential Input AC-Coupled Case
section.
Line Input Unbalanced or Single-Ended AC-Coupled Case
For a single-ended application, the signal swing is reduced by half
because only one input is used for the signal, and the other input is
connected to 0 V. As a result, the input signal capability is reduced
to 5 V rms in a single-ended application. With a common-mode dc
voltage of 7.2 V, the signal can swing between (7.2 V + 7.07 V) =
+14.27 V p-p and (7.2 V − 7 V) = 0.13 V. Therefore, this results
in approximately a 14.14 V p-p differential signal swing and
measures around −6.16 dBFS (ac only with dc high-pass filter)
at the ADC output. The difference in the common-mode dc
voltage between the positive and negative input (7.2 V) would
appear at the ADC output if the signal was not high-pass filtered.
See Figure 20.
The values of the resistor (R1) and capacitor (C1) are similar to
those for the balanced ac-coupled case described in the Line
Input Balanced or Differential Input AC-Coupled Case section.
ADAU1977 Data Sheet
Rev. C | Page 20 of 68
Figure 17. Connecting the Line Level Inputs—Differential DC-Coupled Case
Figure 18. Connecting the Line Level Inputs—Differential AC-Coupled Case
Figure 19. Connecting the Line Level Inputs—Pseudo Differential AC-Coupled Case
Figure 20. Connecting the Line Level Inputs—Single-Ended AC-Coupled Case
ATTENUATOR
14dB
AINx+
ADAU1977
AINx–
V
DIFF
= 10V rms AC
V
CM
= 7V DC
TYPICAL AUDIO P OW E R
AMPLIFIER OUTPUT
10296-016
ATTENUATOR
14dB
AINx+
C1
C3
R1 R2
C2 ADAU1977
AINx–
MICBIAS
V
DIF
f = 10V RM S AC
10296-017
TYPICAL AUDIO PO WER
AMPLIFIER OUTPUT
ATTENUATOR
14dB
AINx+
C1
C3
R1 R2
C2 ADAU1977
AINx–
MICBIAS
V
IN
= 5V rms AC
10296-018
TYPICALAUDIO PO WER
AMPLIFIER OUTPUT
ATTENUATOR
14dB
AINx+
C1
C3
R1
ADAU1977
AINx–
MICBIAS
VIN = 5V rms AC
10296-019
TYPICALAUDIO PO WER
AMPLIFIER OUTPUT
Data Sheet ADAU1977
Rev. C | Page 21 of 68
Microphone Inputs
This section describes some ways to connect the ADAU1977 for
microphone input applications. The MICBIAS voltage and the
bias resistor value depend on the ECM selected. The ADAU1977
can provide the MICBIAS from 5 V up to 9 V in 0.5 V steps. In
an application requiring multiple microphones, care must be
taken not to exceed the MICBIAS output current rating.
ECM Balanced or Differential Input DC-Coupled Case
For example, in a typical ECM, the output signal swing depends
on the MICBIAS voltage. With a typical 8.5 V supply, the ECM can
output a 2 V rms differential signal. The signal at each input pin
has a 1 V rms or 2.8 V p-p signal swing. With a common-mode dc
level of 2/3 × MICBIAS on the AINxP and 1/3 × MICBIAS on
the AINxN pins, this results in around −14 dBFS (ac only with
dc high-pass filter) at the ADC output because the input is 14 dB
below the full-scale input of 10 V rms differential. See Figure 21.
ECM Pseudo Differential Input AC-Coupled Case
For a typical MEMS ECM module, the output signal swing is
low. With a typical 3.3 V supply, the ECM module can output a
2 V rms differential signal. The signal at the input pin has a 1 V rms
or 2.8 V p-p signal swing. For this application, it is recommended
to bias the input pins using resistors to 7 V dc, similar to the
case described in the Line Input Unbalanced or Single-Ended
Pseudo Differential AC-Coupled Case section. See Figure 22.
Figure 21. Connecting the Microphone Inputs—Differential Input DC-Coupled Case
Figure 22. Connecting the Microphone Inputs—Pseudo Differential Input AC-Coupled Case
ATTENUATOR
14dB
AINx+
R
RADAU1977
AINx–
MICBIAS
VIN = 2V rms AC DIF FERE NTI AL
VCM+ ≈ 2/3 × MICBIAS
VCM– ≈ 1/3 × MICBIAS
R = TY P ICAL 300Ω TO 500Ω
MICROPHONE
TYPICAL
ECM M ODULE
NOTES
1. THE DIAGNOSTICS FEATURE IS AVAILABLE.
10296-020
ATTENUATOR
14dB
AINx+
R2R1
C3
ADAU1977
AINx–
MICBIAS
V
MAX
= 5V rms AC
V
DD
TYPICAL ECM
WITH P RE AMP
MODULE
10296-021
NOTES
1. THE DIAGNOSTICS FEATURE IS NOT AVAILABLE.
ADAU1977 Data Sheet
Rev. C | Page 22 of 68
ADC
The ADAU1977 contains four Δ-Σ ADC channels configured
as two stereo pairs with configurable differential/single-ended
inputs. The ADC can operate at a nominal sample rate of 32 kHz
up to 192 kHz. The ADCs include on-board digital antialiasing
filters with 79 dB stop-band attenuation and linear phase response.
Digital outputs are supplied through two serial data output pins
(one for each stereo pair) and a common frame clock (LRCLK)
and bit clock (BCLK). Alternatively, one of the TDM modes can
be used to support up to 16 channels on a single TDM data line.
With smaller amplitude input signals, a 10-bit programmable
digital gain compensation for an individual channel is provided
to scale up the output word to full scale. Care must be taken to
avoid overcompensation (large gain compensation), which leads
to clipping and THD degradation in the ADC.
The ADCs also have a dc-offset calibration algorithm to null
the systematic dc offset of the ADC. This feature is useful for dc
measurement applications.
Inductor Selection
For the boost converter to operate efficiently, the inductor selection
is critical. The two most important parameters for the inductor
are the saturation current rating and the dc resistance. The recom-
mended saturation rating for the inductor must be >1 A. The dc
resistance affects the efficiency of the boost converter. Assuming
that the board trace resistances are negligible for 80% efficiency,
the dc resistance of the inductor should be less than 50 mΩ.
Table 12 lists some of the recommended inductors for the
application.
Table 12. Recommended Inductors1
Value Manufacturer Manufacturer Part Number
2.2 μH Würth Elektronik 7440430022
4.7 μH Würth Elektronik 7440530047
1 Check with the manufacturer for the appropriate temperature ratings for a
given application.
The boost converter has a soft start feature that prevents inrush
current from the input source.
The boost converter has built-in overcurrent and overtemperature
protection. The input current to the boost converter is monitored
and if it exceeds the set current threshold for 1.2 ms, the boost
converter shuts down. The fault condition is recorded into
Register 0x02 and asserts the fault interrupt pin. This condi
tion is cleared after reading the BOOST_OV bit (Bit 2) or the
BOOST_OC bit (Bit 0) in Register 0x02. The overcurrent
protection bit, OC_EN (Bit 1), or the overvoltage protection bit,
OV_EN (Bit 3), is on by default, and it is recommended not to
disable the bit.
Each protection circuit has two modes for recovery after a fault
event: autorecovery and manual recovery. The recovery mode
can be selected using Bit 0 of Register 0x03. The autorecovery
mode attempts to enable the boost converter after a set recovery
time, typically 20 ms. The manual recovery mode enables the boost
converter only if the user writes 1 to the MRCV bit (Bit 1). If the
fault persists, the boost converter remains in shutdown mode
until the fault is cleared.
The boost converter is capable of supplying the 42 mA of total
output current at the MICBIAS output. The boost converter has
overcurrent protection at the input; the threshold is around
900 mA peak. Ensure that the 3.3 V power supply feeding the
boost converter has built-in overcurrent protection because there is
no protection internal to ADAU1977 for a short circuit to any of
the ground pins (AGND/DGND/PGND) at the VBOOST_OUT
or VBOOST_IN pin.
By default, the boost converter is disabled on power-up to allow
the flexibility of connecting an external voltage source at the
VBOOST_IN pin to power the microphone bias circuit. The boost
converter can be enabled by using the BOOST_EN bit (Bit 2 of
Register 0x03).
ADC SUMMING MODES
The four ADCs can be grouped into either a single stereo ADC
or a single mono ADC to increase the signal-to-noise ratio (SNR)
for the application. Two options are available: one option for
summing two channels of the ADC and another option for
summing all four channels of the ADC. Summing is performed
in the digital block.
2-Channel Summing Mode
When the SUM_MODE Bits (Bits[7:6] of Register 0x0E) are
set to 01, the Channel 1 and Channel 2 ADC data are combined
and output from the SDATAOUT1 pin. Similarly, the Channel 3
and Channel 4 ADC data are combined and output from the
SDATAOUT2 pin. As a result, the SNR improves by 3 dB. For
this mode, both Channel 1 and Channel 2 must be connected to
the same input signal source. Similarly, Channel 3 and Channel 4
must be connected to the same input signal source.
4-Channel Summing Mode
When the SUM_MODE Bits (Bits[7:6] of Register 0x0E) are set
to 10, the Channel 1 through Channel 4 ADC data are combined
and output from the SDATAOUT1 pin. As a result, the SNR
improves by 6 dB. For this mode, all four channels must be
connected to the same input signal source.
Data Sheet ADAU1977
Rev. C | Page 23 of 68
DIAGNOSTICS
The diagnostics block monitors the input pins in real time and
reports a fault as an interrupt signal on the FAULT pin (Pin 8),
which triggers sending an interrupt request to an external
controller. The diagnostics status registers (Register 0x11 through
Register 0x14) for Channel 1 through Channel 4 are also updated.
Refer to the register map table (Table 25) and the register details
tables (Table 42, Table 43, Table 44, and Table 45) for more infor-
mation about the diagnostics register content. The diagnostics
can be enabled or disabled for each channel using Bits[3:0] of
Register 0x10. The diagnostics are provided only when MICBIAS
is enabled and the microphone is connected as recommended
in the appropriate application circuit (see Figure 21).
Diagnostics Reporting
The diagnostics status is reported individually for each channel
in Register 0x11 through Register 0x14. The faults listed in
Table 13 are reported on each input pin.
Table 13. Faults Reported
Fault AINxP AINxN
Short to Battery Yes Yes
Short to MICBIAS Yes No
Short to Ground Yes Yes
Short Between Positive and Negative Inputs Yes Yes
Open Input
Yes
Yes
Diagnostics Adjustments
Short Circuit to Battery Supply
When an input terminal is shorted to the battery, the voltage at
the terminal approaches the battery voltage. Any voltage higher
than the set threshold is reported as a fault. The threshold can
be set using the SHT_B_TRIP bits, Bits[1:0] of Register 0x17
(see Table 14).
Table 14. Setting the Short to Battery Threshold
SHT_B_TRIP
(Register 0x17, Bits[1:0]) Short to Battery Threshold
00 0.95 × VBAT
01 0.9 × VBAT
10 0.85 × VBAT
11
0.975 × VBAT
Short Circuit to MICBIAS
This feature is supported only on the AINxP terminal. When
an AINxP terminal is shorted to MICBIAS, the voltage at the
AINxP terminal approaches the MICBIAS voltage. Any voltage
higher than the set threshold is reported as a fault. The threshold
can be set using the SHT_M_TRIP bits, Bits[5:4] of Register 0x17
(see Table 15).
Table 15. Setting the Short to MICBIAS Threshold
SHT_M_TRIP
(Register 0x17, Bits[5:4]) Short to MICBIAS Threshold
00 0.95 × MICBIAS
01 0.9 × MICBIAS
10
0.85 × MICBIAS
11 0.975 × MICBIAS
Short Circuit to Ground
When an input terminal is shorted to ground, the terminal
voltage reaches close to 0 V. Any voltage lower than the set
threshold is reported as a fault. The threshold is referenced to
VREF and, therefore, scales with the voltage at the VREF pin.
The threshold can be set using the SHT_G_TRIP bits, Bits[3:2]
of Register 0x17 (see Table 16).
Table 16.
SHT_G_TRIP
(Register 0x17, Bits[3:2]) Short to Ground Threshold
00 0.2 × VREF
01 0.133 × VREF
10 0.1 × VREF
11
0.266 × VREF
Microphone Terminal Short Circuited
When both input terminals are shorted, both the AINxP and
AINxN input terminals are at the same voltage—around
MICBIAS/2. Any voltage between the set thresholds is reported
as a fault. The upper and lower threshold voltages can be set
using the SHT_T_TRIP bits, Bits[7:6] of Register 0x17 (see
Table 17).
The following equations can be used to calculate the upper and
lower thresholds:
Upper Threshold = MICBIAS(0.5 + x)
Lower Threshold = MICBIAS(0.5 − x)
where x can be set using the SHT_T_TRIP bits, Bits[7:6] of
Register 0x17 (see Table 17).
Table 17.
SHT_T_TRIP
(Register 0x17, Bits [7:6]) x
00
0.035
01 0.017
10 0.071
11 Reserved
ADAU1977 Data Sheet
Rev. C | Page 24 of 68
Microphone Terminals Open
In the event that any of the input terminals becomes open
circuited, AINxP is pulled to MICBIAS and AINxN is pulled to
a common ground. When the AINxP terminal is at a voltage
that is higher than the short to the MICBIAS threshold (set
using Bits[5:4] of Register 0x17) and the AINxN terminal
voltage is at a voltage that is less than the short to the ground
threshold (set using Bits[3:2] of Register 0x17), a fault is
reported. The fault cannot indicate which terminal is open
circuited because any terminal that is open circuited pulls AINxP
to MICBIAS and AINxN to a common ground.
FAULT Pin
The FAULT pin is an output pin that can be programmed to be
active high or active low logic using the IRQ_POL bit (Bit 4 of
Register 0x15). In addition, the FAULT pin can be set using the
IRQ_DRIVE bit (Bit 5 of Register 0x15) to drive always or to drive
only during a fault and is otherwise set to high-Z. The fault status
is registered in the IRQ_RESET bit (Bit 6 of Register 0x15). The
IRQ_RESET bit is a latched bit and is set in the event of a fault
and cleared only after the fault status bit is read.
Fault Timeout
To prevent the false triggering of a fault event, the fault timeout
adjust bits (Bits[5:4] of Register 0x18) are provided. These bits
can be used to set the time that the fault needs to persist before
being reported. The timeout can be set to 0 ms, 50 ms, 100 ms,
or 150 ms using the FAULT_TO bits (Bits[5:4] of Register 0x18).
The default value is 100 ms. A fault is recorded only if the
condition persists for more than a set minimum timeout.
Fault Masking
The faults can be masked to prevent triggering an interrupt
on the FAULT pin. Fault masking can be set using Bits[6:0] of
Register 0x16. The mask can be set for the faults listed in Table 18.
Table 18. Fault Masking
Fault AINxP AINxN
Short to Battery Yes Yes
Short to MICBIAS Yes No
Short to Ground
Yes
Yes
Short Between Positive and Negative Inputs Yes Yes
Open Input Yes Yes
When a fault mask bit is set, it is applied to all the channels.
There is no individual fault mask available per channel using this
bit. To mask individual channels, use the DIAG_MASK[4:1] bits
(Bits[3:0] of Register 0x15).
Diagnostics Sequence
The sequence shown in Figure 23 is recommended for reading
the faults reported by diagnostics.
Figure 23. Diagnostics Sequence
NORMAL FAUL T EVE NT
IRQ TO
SYSTEM MI CRO
FAULT
TIMEOUT
IRQ TO
SYSTEM MI CRO
FAULT
TIMEOUT
IRQ TO
SYSTEM MI CRO
FAULT
TIMEOUT
IRQ TO
SYSTEM MI CRO
FAULT
TIMEOUT
IRQ TO
SYSTEM MI CRO
I
2
C SEQ UENCEI
2
C SEQ UENCEI
2
C SEQ UENCEI
2
C SEQ UENCEI
2
C SEQ UENCE
NORMAL
FAULT
TIMEOUT
AINx+/
AINx–
FAULT
PIN
I
2
C
10296-023
Data Sheet ADAU1977
Rev. C | Page 25 of 68
In the event of a fault on an input pin, the FAULT pin goes low or
high depending on the setting of the IRQ_POL bit in Register 0x15
to send an interrupt request to the system microcontroller. The
system microcontroller responds to the interrupt request by
communicating with the ADAU1977 via the I2C.
The following is the typical interrupt service routine:
1. An interrupt request is generated from the ADAU1977 to
the system microcontroller.
2. Read Register 0x11 through Register 0x14. (It is recom-
mended to read all four diagnostics status registers—
Register 0x11 through Register 0x14—in one sequence.
Reading the registers as a single read may not report the
status accurately.)
3. Write Register 0x15, Bit 6 (the IRQ_RESET bit).
4. Wait for the fault timeout period to expire.
5. If the fault was temporary and did not persist, the interrupt
service ends and the intermittent fault is ignored. If the
fault persists, another interrupt request is generated from
the ADAU1977, and the user should continue on to Step 6.
6. Repeat Step 2 through Step 4 four times.
7. If after the fifth reading, the diagnostics still report the
presence of a fault, the fault exists on the respective input
and must be attended to.
SERIAL AUDIO DATA OUTPUT PORTS—DATA
FORMAT
The serial audio port comprises four pins: BCLK, LRCLK,
SDATAOUT1, and SDATAOUT2. The ADAU1977 ADC outputs
are available on the SDATAOUT1 and SDATAOUT2 pins in
serial format. The BCLK and LRCLK pins serve as the bit clock
and frame clock, respectively. The port can be operated as master
or slave and can be set either in stereo mode (2-channel mode)
or in TDM multichannel mode. The supported popular audio
formats are I2S, left justified (LJ), right justified (RJ).
Stereo Mode
In 2-channel or stereo mode, the SDATAOUT1 outputs ADC
data for Channel 1 and Channel 2, and the SDATOUT2 outputs
ADC data for Channel 3 and Channel 4. Figure 24 through
Figure 28 show the supported audio formats.
Figure 24. I2S Audio Format
Figure 25. LJ Audio Format
Figure 26. RJ Audio Format
BCLK
LRCLK
SDATAOUT1
(I
2
S MODE)
SDATAOUT2
(I
2
S MODE)
NOTES
1. SAI = 0.
2. SDAT A_F MT = 0 (I
2
S).
CHANNEL 1 CHANNEL 2
8 TO 3 2 BCLKs 8 TO 3 2 BCLKs
CHANNEL 3 CHANNEL 4
10296-024
BCLK
LRCLK
SDATAOUT1
(LJ MODE)
SDATAOUT2
(LJ MODE)
CHANNEL 1 CHANNEL 2
CHANNEL 3 CHANNEL 4
10296-025
NOTES
1. SDATA_FMT = 1 ( LJ ) .
BCLK
LRCLK
SDATAOUT1
(RJ MO DE)
SDATAOUT2
(RJ MO DE)
CHANNEL 1 CHANNEL 2
CHANNEL 3 CHANNEL 4
10296-026
NOTES
1. SDATA_FMT = 2 (RJ, 24- BIT) .
ADAU1977 Data Sheet
Rev. C | Page 26 of 68
TDM Mode
Register 0x05 through Register 0x08 provide programmability
for the TDM mode. The TDM slot width, data width, and
channel assignment, as well as the pin used to output the data,
are programmable.
By default, serial data is output on the SDATAOUT1 pin;
however, the SDATA_SEL bit (Bit 7 of Register 0x06) can be
used to change the setting so that serial data is output from the
SDATAOUT2 pin.
The TDM mode supports 2, 4, 8, or 16 channels. The ADAU1977
outputs four channels of data in the assigned slots (Figure 29
shows the data slot assignments). During the unused slots, the
output pin goes high-Z so that the same data line can be shared
with other devices on the TDM bus.
The TDM port can be operated as either a master or a slave.
In master mode, the BCLK and LRCLK are output from the
ADAU1977, whereas in slave mode, the BCLK and LRCLK pins
are set to receive the clock from the master in the system.
Both the nonpulse and pulse modes are supported. In nonpulse
mode, the LRCLK signal is typically 50% of the duty cycle, whereas
in pulse mode, the LRCLK signal must be at least one BCLK wide
(see Figure 27 and Figure 28).
Figure 27. TDM Nonpulse Mode Audio Format
Figure 28. TDM Pulse Mode Audio Format
BCLK
LRCLK
SDATA I
2
S
SDATA LJ
CHANNEL 1
CHANNEL 1
CHANNEL 2 CHANNEL N
CHANNEL 2 CHANNEL N
10296-027
32/24/ 16 BCLKs
8 TO 3 2 BCLKs
8 TO 3 2 BCLKs 8 TO 32 BCLKs 8 TO 3 2 BCLKs
8 TO 3 2 BCLKs 8 T O 32 BCLKs
32/24/ 16 BCLKs 32/24/ 16 BCLKs
SDATA I
2
SCHANNEL 1 CHANNEL 2 CHANNEL N
24 OR 16 BCLKs 24 O R 1 6 BCLKs 24 OR 16 BCL Ks
NOTES
1. SAI = 0 0 1 ( 2 CHANNEL S), 0 1 0 ( 4 CHANNEL S), 0 1 1 ( 8 CHANNEL S), 1 0 0 ( 1 6 CHANNEL S).
2. SDATA_FMT = 00 (I
2
S), 01 ( LJ) , 10 ( RJ, 24- BIT) , 11 (RJ, 16- BIT) .
3. BCLK_ EDGE = 0.
4. LRCL K_ M ODE = 0.
5. SLOT_WIDTH = 00 (32 BCLKs), 01 ( 24 BCLKs), 10 (16 BCLKs).
BCLK
LRCLK
SDATA I
2
S
SDATA LJ
CHANNEL 1
CHANNEL 1
CHANNEL 2 CHANNEL N
CHANNEL 2 CHANNEL N
10296-028
32/24/ 16 BCLKs
8 TO 3 2 BCLKs
8 TO 3 2 BCLKs 8 TO 3 2 BCL Ks 8 TO 32 BCL Ks
8 TO 3 2 BCLKs 8 T O 32 BCLKs
32/24/ 16 BCLKs 32/24/16 BCLKs
SDATA I
2
SCHANNEL 1 CHANNEL 2 CHANNEL N
24 OR 16 BCLKs 24 OR 16 BCL Ks 2 4 OR 1 6 BCL Ks
NOTES
1. SAI = 0 0 1 ( 2 CHANNEL S), 0 1 0 ( 4 CHANNEL S), 0 1 1 ( 8 CHANNEL S), 1 0 0 ( 1 6 CHANNEL S)
2. SDATA_FMT = 00 (I
2
S), 01 ( LJ) , 10 ( RJ, 24- BIT) , 11 (RJ, 16- BIT)
3. BCLK_ EDGE = 0
4. LRCL K_ M ODE = 1
5. SLOT_WIDTH = 00 (32 BCLKs), 01 ( 24 BCLKs), 10 (16 BCLKs)
Data Sheet ADAU1977
Rev. C | Page 27 of 68
Figure 29. TDM Mode Slot Assignment
NUMBER OF BCLK CYCLES = ( NUMBER OF BCLKs/SLOT) × NUMBER OF SLOTS
SLOT2SLOT1
SLOT1 SLOT2 SLOT3 SLOT4
SLOT1 SLOT2 SLOT3 SLOT4 SLOT5 SLOT6 SLOT7 SLOT8
SLOT1 SLOT2 SLOT3 SLOT4 SLOT5 SLOT6 SLOT7 SLOT8 SLOT9 SLOT10 SLOT11 SLOT12 SLOT13 SLOT14 SLOT15 SLOT16
LRCLK
BCLK
SDATAOUTx-TDM2
SDATAOUTx-TDM4
SDATAOUTx-TDM8
SDATAOUTx-TDM16
DATA WIDTH
16/24 BITS
SLOT WIDTH
16/24/32BITS
HIGH-Z HIGH-Z
10296-029
ADAU1977 Data Sheet
Rev. C | Page 28 of 68
The bit clock frequency depends on the sample rate, the slot
width, and the number of bit clocks per slot. Table 19 can be
used to calculate the BCLK frequency.
The sample rate (fS) can range from 8 kHz up to 192 kHz.
However, in master mode, the maximum bit clock frequency
(BCLK) is 24.576 MHz. For example, for a sample rate of
192 kHz, 128 × fS is the maximum possible BCLK frequency.
Therefore, only 128 bit clock cycles are available per TDM
frame. There are two options in this case: either operate with a
32-bit data width in TDM4 or operate with a 16-bit data width
in TDM8. In slave mode, this limitation does not exist because
the bit clock and frame clock are fed to the ADAU1977. Various
combinations of BCLK frequency and mode are available, but
care must be taken to choose the combination that is most
suitable for the application.
Connection Options
Figure 30 through Figure 34 show the available options for
connecting the serial audio port in I2S or TDM mode. In TDM
mode, it is recommended to include the pull-down resistor on
the data signal to prevent the line from floating when the
SDATAOUTx pin of ADAU1977 goes high-Z during an inactive
period. The resistor value should be such that no more than
2 mA is drawn from the SDATAOUTx pin. Although the resistor
value is typically in the range of 10 kΩ to 47 kΩ, the appropriate
resistor value depends on the devices on the data bus.
Table 19. Bit Clock Frequency TDM Mode
BCLK Frequency
Mode 16 Bit Clocks Per Slot 24 Bit Clocks Per Slot 32 Bit Clocks Per Slot
TDM2
32 × f
S
48 × f
S
64 × f
S
TDM4 64 × fS 96 × fS 128 × fS
TDM8 128 × fS 192 × fS 256 × fS
TDM16 256 × fS 384 × fS 512 × fS
Figure 30. Serial Port Connection Option 1—I2S/LJ/RJ Mode, ADAU1977 Master
Figure 31. Serial Port Connection Option 2—I2S/LJ/RJ Mode, ADAU1977 Slave
DSP
SLAVEMASTER
ADAU1977
BCLK
LRCLK
SDATAOUT1
SDATAOUT2
10296-030
DSP
MASTERSLAVE
ADAU1977
BCLK
LRCLK
SDATAOUT1
SDATAOUT2
10296-033
Data Sheet ADAU1977
Rev. C | Page 29 of 68
Figure 32. Serial Port Connection Option 3—TDM Mode, ADAU1977 Master
Figure 33. Serial Port Connection Option 4—TDM Mode, Second ADC Master
Figure 34. Serial Port Connection Option 5—TDM Mode, DSP Master
DSP
SLAVEMASTER
ADAU1977
BCLK
LRCLK
SDATAOUTx
SLAVE
ADAU1977
OR
SI M ILIAR ADC
BCLK
LRCLK
SDATAOUTx
10296-031
DSP
SLAVESLAVE
ADAU1977
BCLK
LRCLK
SDATAOUTx
MASTER
ADAU1977
OR
SI M ILIAR ADC
BCLK
LRCLK
SDATAOUTx
10296-034
DSP
MASTERSLAVE
ADAU1977
BCLK
LRCLK
SDATAOUTx
SLAVE
ADAU1977
OR
SI M ILIAR ADC
BCLK
LRCLK
SDATAOUTx
10296-032
ADAU1977 Data Sheet
Rev. C | Page 30 of 68
CONTROL PORTS
The ADAU1977 control port allows two modes of operation—
either 2-wire I2C mode or 4-wire SPI mode—that are used for
setting the internal registers of the part. Both the I2C and SPI
modes allow read and write capability of the registers. All the
registers are eight bits wide. The registers start at Address 0x00
and end at Address 0x1A.
The control port in both I2C and SPI modes is slave only and,
therefore, requires the master in the system to operate. The registers
can be accessed with or without the master clock to the part.
However, to operate the PLL, serial audio ports, and boost
converter, the master clock is necessary.
By default, the ADAU1977 operates in I2C mode, but the part can
be put into SPI mode by pulling the CLATCH pin low three times.
The control port pins are multifunctional, depending on the
mode in which the part is operating. Table 20 describes the
control port pin functions in both modes.
Table 20. Control Port Pin Functions
I2C Mode SPI Mode
Pin No. Pin Name Pin Functions Pin Type Pin Functions Pin Type
17 SDA/COUT SDA: data I/O COUT: output data O
18
SCL/CCLK
SCL: clock
I
CCLK: input clock
I
19 ADDR0/CLATCH I2C Device Address Bit 0 I CLATCH: input I
20 ADDR1/CIN I2C Device Address Bit 1 I CIN: input data I
Data Sheet ADAU1977
Rev. C | Page 31 of 68
I2C MODE
The ADAU1977 supports a 2-wire serial (I2C-compatible) bus
protocol. Two pins—serial data (SDA) and serial clock (SCL)—
are used to communicate with the system I2C master controller.
In I2C mode, the ADAU1977 is always a slave on the bus, meaning
that it cannot initiate a data transfer. Each slave device on the
I2C bus is recognized by a unique device address. The device
address and R/W byte for the ADAU1977 are shown in Table 21.
The address resides in the first seven bits of the I2C write. Bit 7
and Bit 6 of the I2C address for the ADAU1977 are set by the
levels on the ADDR1 and ADDR0 pins. The LSB of the first I2C
byte (the R/W bit) from the master identifies whether it is a read
or write operation. Logic Level 1 in LSB corresponds to a read
operation, and Logic Level 0 corresponds to a write operation.
Table 21. ADAU1977 I2C First Byte Format
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
ADDR1 ADDR0 1 0 0 0 1 R/W
The first seven bits of the I2C chip address for the ADAU1977
are xx10001. Bit 0 and Bit 1 of the address byte can be set using
the ADDR1 and ADDR0 pins to set the chip address to the
desired value.
The 7-bit I2C device address can be set to one of four possible
options using the ADDR1 and ADDR0 pins:
• I2C Device Address 0010001 (0x11)
• I2C Device Address 0110001 (0x31)
• I2C Device Address 1010001 (0x51)
• I2C Device Address 1110001 (0x71)
In I2C mode, both the SDA and SCL pins require that an
appropriate pull-up resistor be connected to IOVDD. The
voltage on these signal lines should not exceed the voltage on
the IOVDD pin. Figure 46 shows a typical connection diagram
for the I2C mode.
The value of the pull-up resistor for the SDA or SCL pin can be
calculated as follows.
Minimum RPULL UP = (IOVDD – VIL)/ISINK
where:
IOVDD is the I/O supply voltage, typically ranging from 1.8 V
up to 3.3 V.
VIL is the maximum voltage at Logic Level 0 (that is, 0.4 V, as
per the I2C specifications).
ISINK is the current sink capability of the I/O pin.
The SDA pin can sink 2 mA current; therefore, the minimum
value of RPULL UP for an IOVDD of 3.3 V is 1.5 kΩ.
Depending on the capacitance of the board, the speed of the bus
can be restricted to meet the rise time and fall time specifications.
For fast mode with a bit rate time of around 1 Mbps, the rise
time must be less than 550 ns. Use the following equation to
determine whether the rise time specification can be met:
t = 0.8473 × RPULL UP × CBOARD.
To meet the 300 ns rise time requirement, the CBOARD must be
less than 236 pF.
For the SCL pin, the calculations depend on the current sink
capability of the I2C master used in the system.
Addressing
Initially, each device on the I2C bus is in an idle state and monitors
the SDA and SCL lines for a start condition and the proper address.
The I2C master initiates a data transfer by establishing a start
condition, defined by a high-to-low transition on SDA while
SCL remains high. This indicates that an address/data stream
follows. All devices on the bus respond to the start condition
and acquire the next eight bits from the master (the 7-bit address
plus the R/W bit) MSB first. The master sends the 7-bit device
address with the read/write bit to all the slaves on the bus. The
device with the matching address responds by pulling the data
line (SDA) low during the ninth clock pulse. This ninth bit is
known as an acknowledge bit. All other devices withdraw from
the bus at this point and return to the idle condition.
The R/W bit determines the direction of the data. A Logic 0 on the
LSB of the first byte means that the master is to write information
to the slave, whereas a Logic 1 means that the master is to read
information from the slave after writing the address and repeating
the start address. A data transfer takes place until a master initiates
a stop condition. A stop condition occurs when SDA transitions
from low to high while SCL is held high.
Stop and start conditions can be detected at any stage during
the data transfer. If these conditions are asserted out of sequence
during normal read and write operations, the ADAU1977
immediately jumps to the idle condition.
ADAU1977 Data Sheet
Rev. C | Page 32 of 68
Figure 35. I2C Write to ADAU1977 Single Byte
Figure 36. I2C Read from ADAU1977 Single Byte
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
ADDR1 ADDR0 1 0 0 0 1
START STOP
SCL
SDA
FIRST BYTE (DEVI CE ADDRESS) SECO ND BYTE ( RE GI ST ER ADDRES S) THI RD BYTE ( DAT A)
R/W
10296-035
ACK
ADAU1977 ACK
ADAU1977
10296-036
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
ADDR1 ADDR0 1 0 0 0 1
SCL
SDA
THI RD BYTE ( DE VICE ADDRESS) DATA BY TE F ROM ADAU1 9 77
R/W
012345678910 11 12 13 14 15 16 17 18
ADDR1 ADDR0 1 0 0 0 1
START
SCL
SDA
FIRST BYTE (DEVI CE ADDRESS) SE COND BYTE (REGI ST ER ADDRES S)
R/W
NO ACK
STOP
ACK
ADAU1977
ACK
ADAU1977 ACK
ADAU1977
REPEAT START
Data Sheet ADAU1977
Rev. C | Page 33 of 68
I2C Read and Write Operations
Figure 37 shows the format of a single-word write operation.
Every ninth clock pulse, the ADAU1977 issues an acknowledge
by pulling SDA low.
Figure 38 shows the format of a burst mode write sequence.
This figure shows an example of a write to sequential single-
byte registers. The ADAU1977 increments its address register
after every byte because the requested address corresponds to a
register or memory area with a 1-byte word length.
Figure 39 shows the format of a single-word read operation.
Note that the first R/W bit is 0, indicating a write operation.
This is because the address still needs to be written to set up the
internal address. After the ADAU1977 acknowledges the receipt
of the address, the master must issue a repeated start command
followed by the chip address byte with the R/W bit set to 1
(read). This causes the ADAU1977 SDA to reverse and begin
driving data back to the master. The master then responds every
ninth pulse with an acknowledge pulse to the ADAU1977.
Figure 40 shows the format of a burst mode read sequence. This
figure shows an example of a read from sequential single-byte
registers. The ADAU1977 increments its address registers after
every byte because the ADAU1977 uses an 8-bit register address.
Figure 37 to Figure 40 use the following abbreviations:
S = start bit
P = stop bit
AM = acknowledge by master
AS = acknowledge by slave
Figure 37. Single-Word I2C Write Format
Figure 38. Burst Mode I2C Write Format
Figure 39. Single-Word I2C Read Format
Figure 40. Burst Mode I2C Read Format
SCHIPADDRESS,
R/W = 0 AS DATA BYT EAS PREGISTER ADDRESS
8 BIT S
10296-037
SCHIP
ADDRESS,
R/W = 0
AS AS ASREGISTER
ADDRESS
8 BITS
DATA
BYTE 1 DATA
BYTE 2 DATA
BYTE 3 DATA
BYTE 4
AS AS AS P...
CHIP
ADDRESS,
R/W = 0
10296-038
DATA
BYTE 1
SCHIP
ADDRESS,
R/W = 0
AS AS PREGISTER
ADDRESS
8 BIT S
CHIP
ADDRESS,
R/W = 1
AS S
10296-039
DATA
BYTE 1
SCHIP
ADDRESS,
R/W = 0
AMREGISTER
ADDRESS
8 BITS
S
AS AS AS DATA
BYTE 2 AM ... P
CHIP
ADDRESS,
R/W = 1
10296-040
ADAU1977 Data Sheet
Rev. C | Page 34 of 68
SPI MODE
By default, the ADAU1977 is in I2C mode. To invoke SPI control
mode, pull CLATCH low three times. This can be done by per-
forming three dummy writes to the SPI port (the ADAU1977 does
not acknowledge these three writes; see Figure 41). Beginning
with the fourth SPI write, data can be written to or read from
the device. The ADAU1977 can be taken out of SPI mode only
by a full reset initiated by power cycling the device.
The SPI port uses a 4-wire interface, consisting of the CLATCH,
CCLK, CIN, and COUT signals, and it is always a slave port.
The CLATCH signal should go low at the beginning of a trans-
action and high at the end of a transaction. The CCLK signal
latches CIN on a low-to-high transition. COUT data is shifted out
of the ADAU1977 on the falling edge of CCLK and should be
clocked into a receiving device, such as a microcontroller, on
the CCLK rising edge. The CIN signal carries the serial input
data, and the COUT signal carries the serial output data. The
COUT signal remains tristated until a read operation is requested.
This allows direct connection to other SPI-compatible peripheral
COUT ports for sharing the same system controller port. All
SPI transactions have the same basic format shown in Table 24.
A timing diagram is shown in Figure 3. All data should be written
MSB first.
Chip Address R/W
The LSB of the first byte of an SPI transaction is a R/W bit. This bit
determines whether the communication is a read (Logic Level 1)
or a write (Logic Level 0). This format is shown in Table 22.
Table 22. ADAU1977 SPI Address and R/W Byte Format
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 0 0 R/W
Register Address
The 8-bit address word is decoded to a location in one of the
registers. This address is the location of the appropriate register.
Data Bytes
The number of data bytes varies according to the register being
accessed. During a burst mode write, an initial register address is
written followed by a continuous sequence of data for consecutive
register locations.
A sample timing diagram for a single-word SPI write operation to a
register is shown in Figure 42. A sample timing diagram of a single-
word SPI read operation is shown in Figure 43. The COUT pin
goes from being high-Z to being driven at the beginning of Byte 3.
In this example, Byte 0 to Byte 1 contain the device address, the
R/W bit, and the register address to be read. Subsequent bytes
carry the data from the device.
Standalone Mode
The ADAU1977 can also be operated in standalone mode.
However, in standalone mode, the boost converter, microphone
bias, and diagnostics blocks are powered down. To set the part
in standalone mode, pull the SA_MODE pin to IOVDD. In this
mode, some pins change functionality to provide more flexibility
(see Table 23 for more information).
Table 23. Pin Functionality in Standalone Mode
Pin Function Setting Description
ADDR0 0 I2S SAI format
1 TDM modes, determined by the
SDATAOUT2 pin
ADDR1 0 Master mode SAI
1 Slave mode SAI
SDA 0 MCLK = 256 × fS, PLL on
1 MCLK = 384 × fS, PLL on
SCL 0 48 kHz sample rate
1 96 kHz sample rate
SDATAOUT2 0 TDM4—LRCLK pulse
1
TDM8—LRCLK pulse
FAULT 0 Slot 1 to Slot 4 in TDM8
1 Slot 5 to Slot 8 in TDM8
If set for TDM8 mode, the FAULT pin is used as an input for
assigning the ADC data slot to prevent collision with other data
on TDM bus.
Table 24. Generic Control Word Format
Byte 0 Byte 1 Byte 2 Byte 31
Device Address[6:0], R/W Register Address[7:0] Data[7:0] Data[7:0]
1 Continues to end of data.
Data Sheet ADAU1977
Rev. C | Page 35 of 68
Figure 41. SPI Mode Initial Sequence
Figure 42. SPI Write to ADAU1977 Clocking (Single-Word Write Mode)
Figure 43. SPI Read from ADAU1977 Clocking (Single-Word Read Mode)
Figure 44. SPI Write to ADAU1977 (Multiple Bytes)
Figure 45. SPI Read from ADAU1977 (Multiple Bytes)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
CLATCH
CCLK
CIN
10296-041
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
CLATCH
CCLK
CIN
10296-042
REG IST E R ADDRE S S BY TE
DEVICE ADDRES S ( 7 BIT S ) R/W DATA BY TE
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
CLATCH
CCLK
CIN
COUT
10296-043
REG IST E R ADDRE S S BY TE
DEVICE ADDRES S ( 7 BIT S )
R/W DATA BYT E
DATA BY TE F ROM ADAU1977
REGISTER
ADDRESS
BYTE
DATA BY TE1 DATA BYT E 2DEVICE
ADDRESS
BYTE
DATA BY TE n – 1 DATA BYTE n
CLATCH
CCLK
CIN
10296-044
DEVICE
ADDRESS
BYTE
REGISTER
ADDRESS
BYTE
DATA BY TE2 DATA BYTE3DATA BY TE1 DATA BYTE n – 1 DATA BY TE n
CLATCH
CCLK
CIN
COUT
10296-045
ADAU1977 Data Sheet
Rev. C | Page 36 of 68
REGISTER SUMMARY
Table 25 is the control register summary. The registers can be accessed using the I2C control port or the SPI control port.
Table 25. ADAU1977 Register Summary
Reg Name Bits Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset RW
0x00 M_POWER [7:0] S_RST RESERVED PWUP 0x00 RW
0x01 PLL_CONTROL [7:0] PLL_LOCK PLL_MUTE RESERVED CLK_S RESERVED MCS 0x41 RW
0x02 BST_CONTROL [7:0] BST_GOOD FS_RATE BOOST_SW_
FREQ OV_EN BOOST_OV OC_EN BOOST_OC 0x4A RW
0x03 MB_BST_CONTROL [7:0] MB_VOLTS MB_EN BOOST_EN MRCV BOOST_RCVR 0x7D RW
0x04 BLOCK_POWER_SAI [7:0] LR_POL BCLKEDGE LDO_EN VREF_EN ADC_EN4 ADC_EN3 ADC_EN2 ADC_EN1 0x3F RW
0x05 SAI_CTRL0 [7:0] SDATA_FMT SAI FS 0x02 RW
0x06 SAI_CTRL1 [7:0] SDATA_SEL SLOT_WIDTH DATA_WIDTH LR_MODE SAI_MSB BCLKRATE SAI_MS 0x00 RW
0x07 SAI_CMAP12 [7:0] CMAP_C2 CMAP_C1 0x10 RW
0x08 SAI_CMAP34 [7:0] CMAP_C4 CMAP_C3 0x32 RW
0x09 SAI_OVERTEMP [7:0] SAI_DRV_C4 SAI_DRV_C3 SAI_DRV_C2 SAI_DRV_C1 DRV_HIZ OT_MCRV OT_RCVR OT 0xF0 RW
0x0A POSTADC_GAIN1 [7:0] PADC_GAIN1 0xA0 RW
0x0B POSTADC_GAIN2 [7:0] PADC_GAIN2 0xA0 RW
0x0C POSTADC_GAIN3 [7:0] PADC_GAIN3 0xA0 RW
0x0D POSTADC_GAIN4 [7:0] PADC_GAIN4 0xA0 RW
0x0E MISC_CONTROL [7:0] SUM_MODE RESERVED MMUTE RESERVED DC_CAL 0x02 RW
0x10 DIAG_CONTROL [7:0] RESERVED DIAG_EN4 DIAG_EN3 DIAG_EN2 DIAG_EN1 0x0F RW
0x11 DIAG_STATUS1 [7:0] RESERVED MIC_SHORT1 MICH_OPEN1 MICH_SB1 MICH_SG1 MICH_SMB1 MICL_SB1 MICL_SG1 0x00 RW
0x12 DIAG_STATUS2 [7:0] RESERVED MIC_SHORT2 MIC_OPEN2 MICH_SB2 MICH_SG2 MICH_SMB2 MICL_SB2 MICL_SG2 0x00 RW
0x13 DIAG_STATUS3 [7:0] RESERVED MIC_SHORT3 MIC_OPEN3 MICH_SB3 MICH_SG3 MICH_SMB3 MICL_SB3 MICL_SG3 0x00 RW
0x14 DIAG_STATUS4 [7:0] RESERVED MIC_SHORT4 MIC_OPEN4 MICH_SB4 MICH_SG4 MICH_SMB4 MICL_SB4 MICL_SG4 0x00 RW
0x15 DIAG_IRQ1 [7:0] RESERVED IRQ_RESET IRQ_DRIVE IRQ_POL DIAG_MASK4 DIAG_MASK3 DIAG_MASK2 DIAG_MASK1 0x20 RW
0x16 DIAG_IRQ2 [7:0] BST_FAULT_
MASK MIC_SHORT_
MASK MIC_OPEN_
MASK MICH_SB_
MASK MICH_SG_
MASK RESERVED MICL_SB_
MASK MICL_SG_
MASK 0x00 RW
0x17 DIAG_ADJUST1 [7:0] SHT_T_TRIP SHT_M_TRIP SHT_G_TRIP SHT_B_TRIP 0x00 RW
0x18 DIAG_ADJUST2 [7:0] RESERVED FAULT_TO RESERVED HYST_SM_EN HYST_SG_EN HYST_SB_EN 0x20 RW
0x19 ASDC_CLIP [7:0] RESERVED ADC_CLIP4 ADC_CLIP3 ADC_CLIP2 ADC_CLIP1 0x00 RW
0x1A DC_HPF_CAL [7:0] DC_SUB_C4 DC_SUB_C3 DC_SUB_C2 DC_SUB_C1 DC_HPF_C4 DC_HPF_C3 DC_HPF_C2 DC_HPF_C1 0x00 RW
Data Sheet ADAU1977
Rev. C | Page 37 of 68
REGISTER DETAILS
MASTER POWER AND SOFT RESET REGISTER
Address: 0x00, Reset: 0x00, Name: M_POWER
The power management control register is used for enabling boost regulator, microphone bias, PLL, band gap reference, ADC, and LDO
regulator.
Table 26. Bit Descriptions for M_POWER
Bits Bit Name Settings Description Reset Access
7 S_RST Software Reset. The software reset resets all internal circuitry and places
all control registers to their default state. It is not necessary to reset the
ADAU1977 during a power-up or power-down cycle.
0x0 RW
0 Normal Operation
1 Software Reset
[6:1] RESERVED Reserved. 0x00 RW
0 PWUP Master Power-Up Control. The master power-up control fully powers up or
powers down the ADAU1977. This must be set to 1 to power up the
ADAU1977. Individual blocks can be powered down via their respective
power control registers.
0x0 RW
0 Full Power-Down
1 Master Power-Up
ADAU1977 Data Sheet
Rev. C | Page 38 of 68
PLL CONTROL REGISTER
Address: 0x01, Reset: 0x41, Name: PLL_CONTROL
Table 27. Bit Descriptions for PLL_CONTROL
Bits Bit Name Settings Description Reset Access
7 PLL_LOCK PLL Lock Status. PLL lock status bit. When one PLL is locked. 0x0 R
0 PLL Not Locked
1 PLL Locked
6 PLL_MUTE PLL Unlock Automute. When set to 1, mutes the ADC output if PLL
becomes unlocked.
0x1 RW
0 No Automatic Mute on PLL Unlock
1 Automatic Mute with PLL Unlock
5 RESERVED Reserved. 0x0 RW
4 CLK_S PLL Clock Source Select. Selecting input clock source for PLL. 0x0 RW
0 MCLK Used for PLL Input
1 LRCLK Used for PLL Input; Only Supported for Sample Rates > 32 kHz
[2:0] MCS Master Clock Select. MCS bits determine the frequency multiplication
ratio of the PLL. It must be set based on the input MCLK frequency and
sample rate.
0x1 RW
001 256 × fS MCLK for 32 kHz up to 48 kHz (see the PLL section for other
sample rates)
010 384 × fS MCLK for 32 kHz up to 48 kHz (see the PLL section for other
sample rates)
011 512 × fS MCLK for 32 kHz up to 48 kHz (see the PLL section for other
sample rates)
100 768 × fS MCLK for 32 kHz up to 48 kHz (see the PLL section for other
sample rates)
000 128 × fS MCLK for 32 kHz up to 48 kHz (see the PLL section for other
sample rates)
Data Sheet ADAU1977
Rev. C | Page 39 of 68
Bits Bit Name Settings Description Reset Access
101 Reserved
110 Reserved
111 Reserved
DC-TO-DC BOOST CONVERTER CONTROL REGISTER
Address: 0x02, Reset: 0x4A, Name: BST_CONTROL
Table 28. Bit Descriptions for BST_CONTROL
Bits
Bit Name
Settings
Description
Reset
Access
7 BST_GOOD Boost Converter Output Status. 0x0 R
0
Boost Converter Output Not Stabilized
1 Boost Converter Output Good
[6:5] FS_RATE Sample Rate Control for Boost Switching Frequency. 0x2 RW
00
8 kHz/16 kHz/32 kHz/64 kHz/128 kHz f
S
01 11.025 kHz/22.05 kHz/44.1 kHz/88.2 kHz/176.4 kHz fS
10 12 kHz/24 kHz/48 kHz/96 kHz/192 kHz fS
11 Reserved
4 BOOST_SW_FREQ Boost Regulator Switching Frequency. 0x0 RW
0 1.5 MHz Switching Frequency
1 3 MHz Switching Frequency
3 OV_EN Overvoltage Fault Protection Enable. 0x1 RW
0 Disable
1 Enable
2 BOOST_OV Boost Converter Overvoltage Fault Status. 0x0 R
0 Normal Operation
1 Overvoltage Fault
1 OC_EN Overcurrent Fault Protection Enable. 0x1 RW
0 Disable
1 Enable
0 BOOST_OC Boost Converter Overcurrent Fault Status. 0x0 R
0 Normal Operation
1 Boost Overcurrent Protection Active
ADAU1977 Data Sheet
Rev. C | Page 40 of 68
MICBIAS AND BOOST CONTROL REGISTER
Address: 0x03, Reset: 0x7D, Name: MB_BST_CONTROL
Table 29. Bit Descriptions for MB_BST_CONTROL
Bits Bit Name Settings Description Reset Access
[7:4] MB_VOLTS MICBIAS Output Voltage. 0x7 RW
0000 5.0 V
0001 5.5 V
0010 6.0 V
0011
6.5 V
0100 7.0 V
0101 7.5 V
0110 8.0 V
0111 8.5 V
1000 9.0 V
1001 Reserved
1010 Reserved
1011 Reserved
1100 Reserved
1101 Reserved
1110
Reserved
1111 Reserved
3 MB_EN MICBIAS Enable. 0x1 RW
0
MICBIAS Powered Down
1 MICBIAS Enabled
2 BOOST_EN Boost Enable. 0x1 RW
0
Boost Off
1 Boost On
1 MRCV Boost Fault Manual Recovery. 0x0 W
0 Normal Operation
1 Attempt Manual Boost Fault Recovery
Data Sheet ADAU1977
Rev. C | Page 41 of 68
Bits Bit Name Settings Description Reset Access
0 BOOST_RCVR Boost Recovery Mode. 0x1 RW
0 Automatic Fault Recovery
1 Manual Fault Recovery; Use MRCV to Recover
BLOCK POWER CONTROL AND SERIAL PORT CONTROL REGISTER
Address: 0x04, Reset: 0x3F, Name: BLOCK_POWER_SAI
Table 30. Bit Descriptions for BLOCK_POWER_SAI
Bits Bit Name Settings Description Reset Access
7 LR_POL Sets LRCLK Polarity. 0x0 RW
0 LRCLK Low then High
1 LRCLK High then Low
6
BCLKEDGE
Sets the Bit Clock Edge on Which Data Changes.
0x0
RW
0 Data Changes on Falling Edge
1 Data Changes on Rising Edge
5 LDO_EN LDO Regulator Enable. 0x1 RW
0
LDO Powered Down
1 LDO Enabled
4 VREF_EN Voltage Reference Enable. 0x1 RW
0 Voltage Reference Powered Down
1 Voltage Reference Enabled
3 ADC_EN4 ADC Channel 3 Enable. 0x1 RW
0 ADC Channel Powered Down
1 ADC Channel Enabled
2 ADC_EN3 ADC Channel 3 Enable. 0x1 RW
0
ADC Channel Powered Down
1 ADC Channel Enabled
1 ADC_EN2 ADC Channel 2 Enable. 0x1 RW
0 ADC Channel Powered Down
1 ADC Channel Enabled
0 ADC_EN1 ADC Channel 1 Enable. 0x1 RW
0 ADC Channel Powered Down
1 ADC Channel Enabled
ADAU1977 Data Sheet
Rev. C | Page 42 of 68
SERIAL PORT CONTROL REGISTER1
Address: 0x05, Reset: 0x02, Name: SAI_CTRL0
Table 31. Bit Descriptions for SAI_CTRL0
Bits Bit Name Settings Description Reset Access
[7:6] SDATA_FMT Serial Data Format. 0x0 RW
00 I2S Data Delayed from Edge of LRCLK by 1 BCLK
01 Left Justified
10 Right Justified, 24-Bit Data
11
Right Justified, 16-Bit Data
[5:3] SAI Serial Port Mode. 0x0 RW
000 Stereo (I2S, LJ, RJ)
001
TDM2
010 TDM4
011 TDM8
100 TDM16
[2:0] FS Sampling Rate. 0x2 RW
000 8 kHz to 12 kHz
001 16 kHz to 24 kHz
010 32 kHz to 48 kHz
011
64 kHz to 96 kHz
100 128 kHz to 192 kHz
Data Sheet ADAU1977
Rev. C | Page 43 of 68
SERIAL PORT CONTROL REGISTER2
Address: 0x06, Reset: 0x00, Name: SAI_CTRL1
Table 32. Bit Descriptions for SAI_CTRL1
Bits Bit Name Settings Description Reset Access
7 SDATA_SEL SDATAOUTx Pin Selection in TDM4 or Greater Modes. 0x0 RW
0 SDATAOUT1 used for output
1
SDATAOUT2 used for output
[6:5] SLOT_WIDTH Number of BCLKs per Slot in TDM Mode. 0x0 RW
00 32 BCLKs per TDM slot
01 24 BCLKs per TDM slot
10 16 BCLKs per TDM slot
11 Reserved
4 DATA_WIDTH Output Data Bit Width. 0x0 RW
0 24-bit data
1 16-bit data
3 LR_MODE Sets LRCLK Mode. 0x0 RW
0 50% duty cycle clock
1 Pulse—LRCLK is a single BCLK cycle wide pulse
2 SAI_MSB Sets Data to be Input/Output either MSB or LSB First. 0x0 RW
0 MSB first data
1 LSB first data
1 BCLKRATE Sets the Number of Bit Clock Cycles per Data Channel Generated When in
Master Mode.
0x0 RW
0 32 BCLKs/channel
1 16 BCLKs/channel
0 SAI_MS Sets the Serial Port into Master or Slave Mode. 0x0 RW
0 LRCLK/BCLK Slave
1 LRCLK/BCLK Master
ADAU1977 Data Sheet
Rev. C | Page 44 of 68
CHANNEL MAPPING FOR OUTPUT SERIAL PORTS REGISTER
Address: 0x07, Reset: 0x10, Name: SAI_CMAP12
Table 33. Bit Descriptions for SAI_CMAP12
Bits Bit Name Settings Description Reset Access
[7:4] CMAP_C2 ADC Channel 2 Output Mapping. 0x1 RW
0000 Slot 1 for Channel
0001 Slot 2 for Channel
0010
Slot 3 for Channel (on SDATAOUT2 in stereo modes)
0011 Slot 4 for Channel (on SDATAOUT2 in stereo modes)
0100 Slot 5 for Channel (TDM8+ only)
0101 Slot 6 for Channel (TDM8+ only)
0110 Slot 7 for Channel (TDM8+ only)
0111 Slot 8 for Channel (TDM8+ only)
1000 Slot 9 for Channel (TDM16 only)
1001 Slot 10 for Channel (TDM16 only)
1010 Slot 11 for Channel (TDM16 only)
1011 Slot 12 for Channel (TDM16 only)
1100 Slot 13 for Channel (TDM16 only)
1101
Slot 14 for Channel (TDM16 only)
1110 Slot 15 for Channel (TDM16 only)
1111 Slot 16 for Channel (TDM16 only)
Data Sheet ADAU1977
Rev. C | Page 45 of 68
Bits Bit Name Settings Description Reset Access
[3:0] CMAP_C1 ADC Channel 1 Output Mapping. If CMAP is set to a slot that doesn’t exist
for a given serial mode, then that channel will not be driven. For example,
if CMAP is set to Slot 9 and the serial format is I2S, then that channel will
not be driven. If more than one channel is set to the same slot, only the
lowest channel number will be driven; other channels will not be driven.
0x0 RW
0000 Slot 1 for Channel
0001 Slot 2 for Channel
0010 Slot 3 for Channel (on SDATAOUT2 in stereo modes)
0011 Slot 4 for Channel (on SDATAOUT2 in stereo modes)
0100 Slot 5 for Channel (TDM8+ only)
0101
Slot 6 for Channel (TDM8+ only)
0110 Slot 7 for Channel (TDM8+ only)
0111 Slot 8 for Channel (TDM8+ only)
1000 Slot 9 for Channel (TDM16 only)
1001 Slot 10 for Channel (TDM16 only)
1010 Slot 11 for Channel (TDM16 only)
1011 Slot 12 for Channel (TDM16 only)
1100 Slot 13 for Channel (TDM16 only)
1101 Slot 14 for Channel (TDM16 only)
1110 Slot 15 for Channel (TDM16 only)
1111 Slot 16 for Channel (TDM16 only)
ADAU1977 Data Sheet
Rev. C | Page 46 of 68
CHANNEL MAPPING FOR OUTPUT SERIAL PORTS REGISTER
Address: 0x08, Reset: 0x32, Name: SAI_CMAP34
Table 34. Bit Descriptions for SAI_CMAP34
Bits Bit Name Settings Description Reset Access
[7:4] CMAP_C4 ADC Channel 4 Output Mapping. 0x3 RW
0000 Slot 1 for Channel
0001 Slot 2 for Channel
0010 Slot 3 for Channel (on SDATAOUT2 in stereo modes)
0011
Slot 4 for Channel (on SDATAOUT2 in stereo modes)
0100 Slot 5 for Channel (TDM8+ only)
0101 Slot 6 for Channel (TDM8+ only)
0110 Slot 7 for Channel (TDM8+ only)
0111 Slot 8 for Channel (TDM8+ only)
1000 Slot 9 for Channel (TDM16 only)
1001
Slot 10 for Channel (TDM16 only)
1010 Slot 11 for Channel (TDM16 only)
1011 Slot 12 for Channel (TDM16 only)
1100 Slot 13 for Channel (TDM16 only)
1101 Slot 14 for Channel (TDM16 only)
1110 Slot 15 for Channel (TDM16 only)
1111 Slot 16 for Channel (TDM16 only)
Data Sheet ADAU1977
Rev. C | Page 47 of 68
Bits Bit Name Settings Description Reset Access
[3:0] CMAP_C3 ADC Channel 3 Output Mapping. 0x2 RW
0000 Slot 1 for Channel
0001 Slot 2 for Channel
0010 Slot 3 for Channel (on SDATAOUT2 in stereo modes)
0011
Slot 4 for Channel (on SDATAOUT2 in stereo modes)
0100 Slot 5 for Channel (TDM8+ only)
0101 Slot 6 for Channel (TDM8+ only)
0110 Slot 7 for Channel (TDM8+ only)
0111 Slot 8 for Channel (TDM8+ only)
1000 Slot 9 for Channel (TDM16 only)
1001
Slot 10 for Channel (TDM16 only)
1010 Slot 11 for Channel (TDM16 only)
1011 Slot 12 for Channel (TDM16 only)
1100 Slot 13 for Channel (TDM16 only)
1101 Slot 14 for Channel (TDM16 only)
1110 Slot 15 for Channel (TDM16 only)
1111 Slot 16 for Channel (TDM16 only)
ADAU1977 Data Sheet
Rev. C | Page 48 of 68
SERIAL OUTPUT DRIVE AND OVERTEMPERATURE PROTECTION CONTROL REGISTER
Address: 0x09, Reset: 0xF0, Name: SAI_OVERTEMP
Table 35. Bit Descriptions for SAI_OVERTEMP
Bits Bit Name Settings Description Reset Access
7 SAI_DRV_C4 Channel 4 Serial Output Drive Enable. 0x1 RW
0 Channel Not Driven on Serial Output Port
1 Channel Driven on Serial Output Port; Slot Determined by CMAP
6 SAI_DRV_C3 Channel 3 Serial Output Drive Enable. 0x1 RW
0 Channel Not Driven on Serial Output Port
1 Channel Driven on Serial Output Port; Slot Determined by CMAP
5 SAI_DRV_C2 Channel 2 Serial Output Drive Enable. 0x1 RW
0 Channel Not Driven on Serial Output Port
1
Channel Driven on Serial Output Port; Slot Determined by CMAP
4 SAI_DRV_C1 Channel 1 Serial Output Drive Enable. 0x1 RW
0 Channel Not Driven on Serial Output Port
1
Channel Driven on Serial Output Port; Slot Determined by CMAP
3 DRV_HIZ Select Whether to Tristate Unused SAI Channels or to Actively Drive These
Data Slots.
0x0 RW
0
Unused Outputs Driven Low
1 Unused Outputs High-Z
2 OT_MCRV Overtemperature Manual Recovery Attempt. 0x0 W
0
Normal Operation
1 Attempt Manual Overtemperature Recovery
1 OT_RCVR Overtemperature Manual Recovery. 0x0 RW
0
Automatic Recovery from Overtemperature Fault
1 Manual Recovery from Overtemperature Fault, Must Set OT_MCRV Register
Data Sheet ADAU1977
Rev. C | Page 49 of 68
Bits Bit Name Settings Description Reset Access
0 OT Overtemperature Status. 0x0 R
0 Normal Operation
1 Overtemperature Fault
POST ADC GAIN CHANNEL 1 CONTROL REGISTER
Address: 0x0A, Reset: 0xA0, Name: POSTADC_GAIN1
Table 36. Bit Descriptions for POSTADC_GAIN1
Bits Bit Name Settings Description Reset Access
[7:0]
PADC_GAIN1
Channel 1 Post ADC Gain.
0xA0
RW
00000000 +60 dB Gain
00000001 +59.625 dB Gain
00000010 +59.25 dB Gain
... ...
10011111 +0.375 dB Gain
10100000 0 dB Gain
10100001 −0.375 dB Gain
... ...
11111110 −35.625 dB Gain
11111111 Mute
ADAU1977 Data Sheet
Rev. C | Page 50 of 68
POST ADC GAIN CHANNEL 2 CONTROL REGISTER
Address: 0x0B, Reset: 0xA0, Name: POSTADC_GAIN2
Table 37. Bit Descriptions for POSTADC_GAIN2
Bits Bit Name Settings Description Reset Access
[7:0] PADC_GAIN2 Channel 2 Post ADC Gain. 0xA0 RW
00000000 +60 dB Gain
00000001 +59.625 dB Gain
00000010
+59.25 dB Gain
... ...
10011111 +0.375 dB Gain
10100000 0 dB Gain
10100001 −0.375 dB Gain
... ...
11111110 −35.625 dB Gain
11111111 Mute
Data Sheet ADAU1977
Rev. C | Page 51 of 68
POST ADC GAIN CHANNEL 3 CONTROL REGISTER
Address: 0x0C, Reset: 0xA0, Name: POSTADC_GAIN3
Table 38. Bit Descriptions for POSTADC_GAIN3
Bits Bit Name Settings Description Reset Access
[7:0] PADC_GAIN3 Channel 3 Post ADC Gain. 0xA0 RW
00000000 +60 dB Gain
00000001 +59.625 dB Gain
00000010
+59.25 dB Gain
... ...
10011111 +0.375 dB Gain
10100000 0 dB Gain
10100001 −0.375 dB Gain
... ...
11111110 −35.625 dB Gain
11111111 Mute
ADAU1977 Data Sheet
Rev. C | Page 52 of 68
POST ADC GAIN CHANNEL 4 CONTROL REGISTER
Address: 0x0D, Reset: 0xA0, Name: POSTADC_GAIN4
Table 39. Bit Descriptions for POSTADC_GAIN4
Bits Bit Name Settings Description Reset Access
[7:0] PADC_GAIN4 Channel 4 Post ADC Gain. 0xA0 RW
00000000 +60 dB Gain
00000001 +59.625 dB Gain
00000010
+59.25 dB Gain
... ...
10011111 +0.375 dB Gain
10100000 0 dB Gain
10100001 −0.375 dB Gain
... ...
11111110 −35.625 dB Gain
11111111 Mute
Data Sheet ADAU1977
Rev. C | Page 53 of 68
HIGH-PASS FILTER AND DC OFFSET CONTROL REGISTER AND MASTER MUTE
Address: 0x0E, Reset: 0x02, Name: MISC_CONTROL
Table 40. Bit Descriptions for MISC_CONTROL
Bits Bit Name Settings Description Reset Access
[7:6] SUM_MODE Channel Summing Mode Control for Higher SNR. 0x0 RW
00 Normal 4-Channel Operation
01
2-Channel Summing Operation (See the ADC Summing Modes Section)
10 1-Channel Summing Operation (See the ADC Summing Modes Section)
11 Reserved
5 RESERVED Reserved. 0x0 RW
4 MMUTE Master Mute. 0x0 RW
0
Normal Operation
1 All Channels Muted
[3:1] RESERVED Reserved. 0x1 RW
0 DC_CAL DC Calibration Enable. 0x0 RW
0 Normal Operation
1 Perform DC Calibration
ADAU1977 Data Sheet
Rev. C | Page 54 of 68
DIAGNOSTICS CONTROL REGISTER
Address: 0x10, Reset: 0x0F, Name: DIAG_CONTROL
Table 41. Bit Descriptions for DIAG_CONTROL
Bits Bit Name Settings Description Reset Access
[7:4] RESERVED Reserved. 0x0 RW
3 DIAG_EN4 Diagnostics Enable Channel 4. 0x1 RW
0 Diagnostics Disabled
1 Diagnostics Enabled
2 DIAG_EN3 Diagnostics Enable Channel 3. 0x1 RW
0
Diagnostics Disabled
1 Diagnostics Enabled
1 DIAG_EN2 Diagnostics Enable Channel 2. 0x1 RW
0
Diagnostics Disabled
1 Diagnostics Enabled
0 DIAG_EN1 Diagnostics Enable Channel 1. 0x1 RW
0
Diagnostics Disabled
1 Diagnostics Enabled
Data Sheet ADAU1977
Rev. C | Page 55 of 68
DIAGNOSTICS REPORT REGISTER CHANNEL 1
Address: 0x11, Reset: 0x00, Name: DIAG_STATUS1
Table 42. Bit Descriptions for DIAG_STATUS1
Bits Bit Name Settings Description Reset Access
7 RESERVED Reserved. 0x0 RW
6
MIC_SHORT1
Mic Terminals Shorted.
0x0
R
0 Normal Operation
1 Mic Terminals Shorted
5
MICH_OPEN1
Mic Open Connection.
0x0
R
0 Normal Operation
1 Mic Open Connection
4
MICH_SB1
Mic High Shorted to Supply.
0x0
R
0 Normal Operation
1 Mic High Shorted to Supply
3 MICH_SG1 Mic High Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic High Shorted to Ground
2 MICH_SMB1 Mic High Shorted to MICBIAS. 0x0 R
0 Normal Operation
1 Mic High Shorted to MICBIAS
1 MICL_SB1 Mic Low Shorted to Supply. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Supply
0 MICL_SG1 Mic Low Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Ground
ADAU1977 Data Sheet
Rev. C | Page 56 of 68
DIAGNOSTICS REPORT REGISTER CHANNEL 2
Address: 0x12, Reset: 0x00, Name: DIAG_STATUS2
Table 43. Bit Descriptions for DIAG_STATUS2
Bits Bit Name Settings Description Reset Access
7 RESERVED Reserved. 0x0 RW
6
MIC_SHORT2
Mic Terminals Shorted.
0x0
R
0 Normal Operation
1 Mic Terminals Shorted
5
MIC_OPEN2
Mic Open Connection.
0x0
R
0 Normal Operation
1 Mic Open Connection
4
MICH_SB2
Mic High Shorted to Supply.
0x0
R
0 Normal Operation
1 Mic High Shorted to Supply
3 MICH_SG2 Mic High Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic High Shorted to Ground
2 MICH_SMB2 Mic High Shorted to MICBIAS. 0x0 R
0 Normal operation
1 Mic High Shorted to MICBIAS
1 MICL_SB2 Mic Low Shorted to Supply. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Supply
0 MICL_SG2 Mic Low Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Ground
Data Sheet ADAU1977
Rev. C | Page 57 of 68
DIAGNOSTICS REPORT REGISTER CHANNEL 3
Address: 0x13, Reset: 0x00, Name: DIAG_STATUS3
Table 44. Bit Descriptions for DIAG_STATUS3
Bits Bit Name Settings Description Reset Access
7 RESERVED Reserved. 0x0 RW
6
MIC_SHORT3
Mic Terminals Shorted.
0x0
R
0 Normal Operation
1 Mic Terminals Shorted
5
MIC_OPEN3
Mic Open Connection.
0x0
R
0 Normal Operation
1 Mic Open Connection
4
MICH_SB3
Mic High Shorted to Supply.
0x0
R
0 Normal Operation
1 Mic High Shorted to Supply
3 MICH_SG3 Mic High Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic High Shorted to Ground
2 MICH_SMB3 Mic High Shorted to MICBIAS. 0x0 R
0 Normal Operation
1 Mic High Shorted to MICBIAS
1 MICL_SB3 Mic Low Shorted to Supply. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Supply
0 MICL_SG3 Mic Low Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Ground
ADAU1977 Data Sheet
Rev. C | Page 58 of 68
DIAGNOSTICS REPORT REGISTER CHANNEL 4
Address: 0x14, Reset: 0x00, Name: DIAG_STATUS4
Table 45. Bit Descriptions for DIAG_STATUS4
Bits Bit Name Settings Description Reset Access
7 RESERVED Reserved. 0x0 RW
6
MIC_SHORT4
Mic Terminals Shorted.
0x0
R
0 Normal Operation
1 Mic Terminals Shorted
5
MIC_OPEN4
Mic Open Connection.
0x0
R
0 Normal Operation
1 Mic Open Connection
4
MICH_SB4
Mic High Shorted to Supply.
0x0
R
0 Normal Operation
1 Mic High Shorted to Supply
3 MICH_SG4 Mic High Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic High Shorted to Ground
2 MICH_SMB4 Mic High Shorted to MICBIAS. 0x0 R
0 Normal Operation
1 Mic High Shorted to MICBIAS
1 MICL_SB4 Mic Low Shorted to Supply. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Supply
0 MICL_SG4 Mic Low Shorted to Ground. 0x0 R
0 Normal Operation
1 Mic Low Shorted to Ground
Data Sheet ADAU1977
Rev. C | Page 59 of 68
DIAGNOSTICS INTERRUPT PIN CONTROL REGISTER 1
Address: 0x15, Reset: 0x20, Name: DIAG_IRQ1
Table 46. Bit Descriptions for DIAG_IRQ1
Bits Bit Name Settings Description Reset Access
7
RESERVED
Reserved.
0x0
RW
6 IRQ_RESET FAULT Pin Reset. 0x0 RW
0 Normal Operation
1 Reset FAULT Pin
5 IRQ_DRIVE FAULT Pin Drive Options. 0x1 RW
0
FAULT Pin Always Driven
1 FAULT Pin Only Driven During Fault, Otherwise High-Z
4 IRQ_POL FAULT Pin Polarity. 0x0 RW
0 Faults Set FAULT Pin Low
1
Faults Set FAULT Pin High
3 DIAG_MASK4 FAULT Pin Mask for All Channel 4 Faults. 0x0 RW
0 Faults on Channel 4 Trigger FAULT Pin
1 Faults on Channel 4 Do Not Trigger FAULT Pin
2 DIAG_MASK3 FAULT Pin Mask for All Channel 3 Faults. 0x0 RW
0 Faults on Channel 3 Trigger FAULT Pin
1 Faults on Channel 3 Do Not Trigger FAULT Pin
1 DIAG_MASK2 FAULT Pin Mask for All Channel 2 Faults. 0x0 RW
0 Faults on Channel 2 Trigger FAULT Pin
1
Faults on Channel 2 Do Not Trigger FAULT Pin
0 DIAG_MASK1 FAULT Pin Mask for All Channel 1 Faults. 0x0 RW
0 Faults on Channel 1 Trigger FAULT Pin
1 Faults on Channel 1 Do Not Trigger FAULT Pin
ADAU1977 Data Sheet
Rev. C | Page 60 of 68
DIAGNOSTICS INTERRUPT PIN CONTROL REGISTER 2
Address: 0x16, Reset: 0x00, Name: DIAG_IRQ2
Table 47. Bit Descriptions for DIAG_IRQ2
Bits Bit Name Settings Description Reset Access
7 BST_FAULT_MASK FAULT Pin Mask for Boost Faults. 0x0 RW
0 Boost Faults Assert FAULT Pin
1 Boost Faults Do Not Assert FAULT Pin
6 MIC_SHORT_MASK FAULT Pin Mask for Mic Terminal Short Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
5 MIC_OPEN_MASK FAULT Pin Mask for Mic Open Connection Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
4 MICH_SB_MASK FAULT Pin Mask for Mic High Short to Supply Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
3 MICH_SG_MASK FAULT Pin Mask for Mic High Short to Ground Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
1 MICL_SB_MASK FAULT Pin Mask for Mic Low Short to Supply Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
0 MICL_SG_MASK FAULT Pin Mask for Mic Low Short to Ground Fault. 0x0 RW
0 Faults Trigger FAULT Pin
1 Faults Do Not Trigger FAULT Pin
Data Sheet ADAU1977
Rev. C | Page 61 of 68
DIAGNOSTICS ADJUSTMENTS REGISTER 1
Address: 0x17, Reset: 0x00, Name: DIAG_ADJUST1
Table 48. Bit Descriptions for DIAG_ADJUST1
Bits Bit Name Settings Description Reset Access
[7:6] SHT_T_TRIP Short Fault to Other Terminal Trip Point Adjust. 0x0 RW
00 0.465 × MICBIAS to 0.535 × MICBIAS
01 0.483 × MICBIAS to 0.517 × MICBIAS
10
0.429 × MICBIAS to 0.571 × MICBIAS
11 Reserved
[5:4] SHT_M_TRIP Short Fault to Mic Bias Trip Point Adjust. 0x0 RW
00
0.95 × MICBIAS
01 0.9 × MICBIAS
10 0.85 × MICBIAS
11 0.975 × MICBIAS
[3:2] SHT_G_TRIP Short Fault to Ground Trip Point Adjust. 0x0 RW
00 0.2 × VREF
01 0.133 × VREF
10 0.1 × VREF
11
0.266 × VREF
[1:0] SHT_B_TRIP Short Fault to Supply/Battery Trip Point Adjust. 0x0 RW
00 0.95 × VBAT
01
0.9 × VBAT
10 0.85 × VBAT
11 0.975 × VBAT
ADAU1977 Data Sheet
Rev. C | Page 62 of 68
DIAGNOSTICS ADJUSTMENTS REGISTER 2
Address: 0x18, Reset: 0x20, Name: DIAG_ADJUST2
Table 49. Bit Descriptions for DIAG_ADJUST2
Bits Bit Name Settings Description Reset Access
[7:6] RESERVED Reserved. 0x0 RW
[5:4] FAULT_TO Fault Timeout Adjust. 0x2 RW
00 No Fault Timeout Period (That Is, the Time That the Fault Needs to Persist
Before Being Reported)
01 50 ms Fault Timeout Period
10 100 ms Fault Timeout Period (Default)
11 150 ms Fault Timeout Period
3 RESERVED Reserved. 0x0 RW
2
HYST_SM_EN
Hysteresis Short to MICBIAS Enable.
0x0
RW
0 Disable
1 Enable
1 HYST_SG_EN Hysteresis Short to Ground Enable. 0x0 RW
0 Disable
1 Enable
0 HYST_SB_EN Hysteresis Short to Battery Enable. 0x0 RW
0 Disable
1 Enable
Data Sheet ADAU1977
Rev. C | Page 63 of 68
ADC CLIPPING STATUS REGISTER
Address: 0x19, Reset: 0x00, Name: ASDC_CLIP
Table 50. Bit Descriptions for ASDC_CLIP
Bits Bit Name Settings Description Reset Access
[7:4] RESERVED Reserved. 0x0 RW
3 ADC_CLIP4 ADC Channel 4 Clip Status. 0x0 R
0 Normal Operation
1 ADC Channel Clipping
2 ADC_CLIP3 ADC Channel 3 Clip Status. 0x0 R
0
Normal Operation
1 ADC Channel Clipping
1 ADC_CLIP2 ADC Channel 2 Clip Status. 0x0 R
0
Normal Operation
1 ADC Channel Clipping
0 ADC_CLIP1 ADC Channel 1 Clip Status. 0x0 R
0
Normal Operation
1 ADC Channel Clipping
ADAU1977 Data Sheet
Rev. C | Page 64 of 68
DIGITAL DC HIGH-PASS FILTER AND CALIBRATION REGISTER
Address: 0x1A, Reset: 0x00, Name: DC_HPF_CAL
Table 51. Bit Descriptions for DC_HPF_CAL
Bits Bit Name Settings Description Reset Access
7 DC_SUB_C4 Channel 4 DC Subtraction from Calibration. 0x0 RW
0 No DC Subtraction
1 DC Value from DC Calibration Is Subtracted
6 DC_SUB_C3 Channel 3 DC Subtraction from Calibration. 0x0 RW
0 No DC Subtraction
1 DC Value from DC Calibration Is Subtracted
5
DC_SUB_C2
Channel 2 DC Subtraction from Calibration.
0x0
RW
0 No DC Subtraction
1 DC Value from DC Calibration Is Subtracted
4
DC_SUB_C1
Channel 1 DC Subtraction from Calibration.
0x0
RW
0 No DC Subtraction
1 DC Value from DC Calibration Is Subtracted
3
DC_HPF_C4
Channel 4 DC High-Pass Filter Enable.
0x0
RW
0 HPF Off
1 HPF On
2 DC_HPF_C3 Channel 3 DC High-Pass Filter Enable. 0x0 RW
0 HPF Off
1 HPF On
1 DC_HPF_C2 Channel 2 DC High-Pass Filter Enable. 0x0 RW
0 HPF Off
1 HPF On
0 DC_HPF_C1 Channel 1 DC High-Pass Filter Enable. 0x0 RW
0 HPF Off
1 HPF On
Data Sheet ADAU1977
Rev. C | Page 65 of 68
APPLICATIONS CIRCUIT
Figure 46. Typical Application Schematic—Two Microphones, Two Line Inputs, I2C and I2S Mode
I2C/SPI
CONTROL
MIC1
V
AC
= 2 V DIFF
C9
10µF ELECTROLYTIC
1nF MAX MLCC
C18
10µF C19
0.1µF
C20 C21
R17
+3. 3V (AVDD2)
C10
10µF
ML CC X7R
10µF
ML CC X7R
C11
0.1µF
C12
0.1µF
+3.3V
C13
0.1µF
C14
0.1µF
4.7µH
C15
0.1µF R
EXT
R9
R10
R11
R12
R15
R16
C7
0.1µF
C16
10µF
ML CC X7R
+14.4V
C1 TO C8 = 1000pF
R1 TO R4 T YP = 500Ω ±0.1%
R17
C20
C21
4.87kΩ
2200pF
39nF
PLL INPUT OPTION
LRCLK MCLK
1kΩ
390pF
5600pF
NOTES
1. R9, R10 = TYPICAL 2kΩ.
2. R11 THROUG H R1 4 USED F OR SETT ING T HE DEVICE IN I
2
C MODE.
3. R15, R16 = TYPICAL 47kΩ.
4. PLL LOOP FILTER:
5. FO R MO RE INFORMATIO NABOUT CAL CULATI NG THE VALUE OF R
EXT
, SEE THE POWER-O N RESET SEQUENCE SECTION.
AIN1+
MICBIAS
VBOOST_OUT
SW
AVDD1
AVDD3
AVDD2
DVDD
IOVDD
LRCLK
BCLK
SDATAOUT1 TO DSP
IOVDD
SDATAOUT2
SCL/CCLK
SDA/COUT
ADDR1/CIN
ADDR0/CLATCH
FAULT
PD/RESET
+1. 8V OR + 3. 3V
VBAT (LO AD DUMP SUPRESSED)
VBOOST_IN
MB_GND
VBAT
AVDDx AGND1 AGND3
AVDD2
AVDD1
PGND
ATTENUATOR
14dB
PROGRAMM ABL E GAI N
DECIMATOR/HPF
DC CALI BRATION
SERIALAUDIO PORT
AVDD3
ADC
BOOST
CONVERTER
I
OUT
50mA3.3V TO 1. 8V
REGULATOR
ADC
ADC
ADC
AGND2
AGNDx
AGND2
PGND
AGND1
AGND2
AGND3
DGND
VREF
MCLKIN
PLL_FILT
SA_MODE
C1 C2 C3 C4 C5 C6 C7 C8 R4R2
R3
R13 R14
R1
AIN1–
AIN2+
AIN2–
AIN3+
AIN3–
DIAGNOSTICS
AIN4+
AIN4–
MIC2
V
AC
= 2 V DIFF
LINE1
V
CM
= 7V, V
AC
= 10V DIFF
LINE2
V
CM
= 7V, V
AC
= 10V DIFF
MICRO-
CONTROLLER
5V TO 9V
PROG
BIAS
10296-046
ADAU1977
BG
REF PLL
ADAU1977 Data Sheet
Rev. C | Page 66 of 68
OUTLINE DIMENSIONS
Figure 47. 40-Lead Lead Frame Chip Scale Package [LFCSP_WQ]
6 mm × 6 mm Body, Very Very Thin Quad
(CP-40-14)
Dimensions shown in millimeters
ORDERING GUIDE
Model1, 2 Temperature Range Package Description Package Option
ADAU1977WBCPZ –40°C to +105°C 40-Lead LFCSP_WQ CP-40-14
ADAU1977WBCPZ-R7 –40°C to +105°C 40-Lead LFCSP_WQ, 7” Tape and Reel CP-40-14
ADAU1977WBCPZ-RL –40°C to +105°C 40-Lead LFCSP_WQ, 13” Tape and Reel CP-40-14
EVAL-ADAU1977Z Evaluation Board
1 Z = RoHS Compliant Part.
2 W = Qualified for Automotive Applications.
AUTOMOTIVE PRODUCTS
The ADAU1977W models are available with controlled manufacturing to support the quality and reliability requirements of automotive
applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers
should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in
automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain
the specific Automotive Reliability reports for these models.
0.50
BSC
BOTTOM VIEWTOP VI EW
PI N 1
INDICATOR
EXPOSED
PAD
PI N 1
INDICATOR
SEATING
PLANE
0.05 M AX
0.02 NOM
0.20 RE F
COPLANARITY
0.08
0.30
0.25
0.18
6.10
6.00 S Q
5.90
0.80
0.75
0.70
FOR PRO P E R CONNECTI ON O F
THE EXPOSED PAD, REFER TO
THE P IN CONFI GURAT IO N AND
FUNCTION DES CRIPTI ONS
SECTION OF THIS DATA SHEET.
0.45
0.40
0.35
0.25 M IN
4.05
3.90 S Q
3.75
COM P LIANT T O JEDE C S TANDARDS M O-220-WJJD.
40
1
11
20
21
30
31
10
05-06-2011-A
Data Sheet ADAU1977
Rev. C | Page 67 of 68
NOTES
