LM86CIMMNOPB - NATIONAL SEMICONDUCTOR

LM83

LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire

Interface

Literature Number: SNIS111A

LM83

Triple-Diode Input and Local Digital Temperature Sensor

with Two-Wire Interface

General Description

The LM83 is a digital temperature sensor with a 2 wire serial

interface that senses the voltage and thus the temperature of

three remote diodes using a Delta-Sigma analog-to-digital

converter with a digital over-temperature detector. The LM83

accurately senses its own temperature as well as the tem-

perature of three external devices, such as Pentium II®Pro-

cessors or diode connected 2N3904s. The temperature of

anyASIC can be detected using the LM83 as long as a dedi-

cated diode (semiconductor junction) is available on the die.

Using the SMBus interface a host can access the LM83’s

registers at any time. Activation of a T_CRIT_A output oc-

curs when any temperature is greater than a programmable

comparator limit, T_CRIT. Activation of an INT output occurs

when any temperature is greater than its corresponding pro-

grammable comparator HIGH limit.

The host can program as well as read back the state of the

T_CRIT register and the four T_HIGH registers. Three state

logic inputs allow two pins (ADD0, ADD1) to select up to 9

SMBus address locations for the LM83. The sensor powers

up with default thresholds of 127˚C for T_CRIT and all

T_HIGHs. The LM83 is pin for pin and register compatible

with the LM84 as well as the Maxim MAX1617 and the Ana-

log Devices ADM1021.

Features

nAccurately senses die temperature of 3 remote ICs, or

diode junctions

nOn-board local temperature sensing

nSMBus and I

C compatible interface, supports

SMBus 1.1 TIMEOUT

nTwo interrupt outputs: INT and T_CRIT_A

nRegister readback capability

n7 bit plus sign temperature data format, 1 ˚C resolution

n2 address select pins allow connection of 9 LM83s on a

single bus

Key Specifications

jSupply Voltage 3.0V to 3.6V

jSupply Current 0.8mA (max)

jLocal Temp Accuracy (includes quantization error)

0˚C to +85˚C ±3.0˚C (max)

jRemote Diode Temp Accuracy (includes quantization

error) +25˚C to +100˚C ±3˚C (max)

0˚C to +125˚C ±4˚C (max)

Applications

nSystem Thermal Management

nComputers

nElectronic Test Equipment

nOffice Electronics

nHVAC

Simplified Block Diagram

SMBus™is a trademark of the Intel Corporation.

Pentium II®is a registered trademark of the Intel Corporation.

I2C®is a registered trademark of the Philips Corporation.

DS101058-1

November 1999

LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface

Connection Diagram Ordering Information

Order

Number

Package

Number

Transport

Media

LM83CIMQA MQA16A

(QSOP-16) 95 Units in

Rail

LM83CIMQAX MQA16A

(QSOP-16)

2500 Units on

Tape and

Reel

Typical Application

Pin Description

Label Pin #Function Typical Connection

D1+, D2+, D3+ 1, 3, 5

Diode Current Source To Diode Anode. Connected to remote discrete

diode junction or to the diode junction on a remote

IC whose die temperature is being sensed. When

not used they should be left floating.

2Positive Supply Voltage

Input DC Voltage from 3.0 V to 3.6 V

QSOP-16

DS101058-2

TOP VIEW

DS101058-3

LM83

www.national.com 2

Pin Description (Continued)

Label Pin #Function Typical Connection

D− 4 Diode Return Current

Sink To all Diode Junction Cathodes using a star

connection to pin. Must float when not used.

ADD0–ADD1 10, 6 User-Set SMBus (I

Address Inputs Ground (Low, “0”), V

(High, “1”) or open

(“TRI-LEVEL”)

GND 7, 8 Power Supply Ground Ground

NC 9, 13, 15

Manufacturing test pins. Left floating. PC board traces may be routed

through the pads for these pins, although the

components that drive these traces should share

the same supply as the LM83 so that the Absolute

Maximum Rating, Voltage at Any Pin, is not

violated.

INT 11 Interrupt Output,

open-drain Pull Up Resistor, Controller Interrupt or Alert Line

SMBData 12 SMBus (I

C) Serial

Bi-Directional Data Line,

open-drain output

From and to Controller, Pull-Up Resistor

SMBCLK 14 SMBus (I

C) Clock Input From Controller, Pull-Up Resistor

T_CRIT_A 16 Critical Temperature

Alarm, open-drain output Pull Up Resistor, Controller Interrupt Line or

System Shutdown

LM83

www.national.com3

Absolute Maximum Ratings (Note 1)

Supply Voltage −0.3 V to 6.0 V

Voltage at Any Pin −0.3 V to

+ 0.3 V)

D− Input Current ±1mA

Input Current at All Other Pins (Note

2) 5 mA

Package Input Current (Note 2) 20 mA

SMBData, T_CRIT_A, INT Output

Sink Current 10 mA

SMBCLK, SMBData, T_CRIT_A, INT

Output Voltage 6.0 V

Storage Temperature −65˚C to +150˚C

Soldering Information, Lead Temperature

QSOP Package (Note 3)

Vapor Phase (60 seconds) 215˚C

Infrared (15 seconds) 220˚C

ESD Susceptibility (Note 4)

Human Body Model 2000 V

Machine Model 200 V

Operating Ratings

(Notes 1, 5)

Specified Temperature Range T

MIN

to T

MAX

LM83 −40˚C to +125˚C

Supply Voltage Range (V

) +3.0V to +3.6V

Temperature-to-Digital Converter Characteristics

Unless otherwise noted, these specifications apply for V

=+3.0Vdc to 3.6Vdc. Boldface limits apply for T

MIN

MAX

;all other limits T

=+25˚C, unless otherwise noted.

Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

Temperature Error using Local

Diode ((Note 8)) T

= 0 ˚C to +85˚C,

=+3.3V ±1±3˚C (max)

= −40 ˚C to +125˚C,

=+3.3V ±4˚C (max)

Temperature Error using Remote

Diode ((Note 8)) T

= +60 ˚C to +100˚C,

=+3.3V ±3˚C (max)

= 25 ˚C to +100˚C,

=+3.3V ±3˚C (max)

= 0 ˚C to +125˚C,

=+3.3V ±4˚C (max)

Diode Channel to Channel Matching 0 ˚C

Resolution 8 Bits

1˚C

Conversion Time of All

Temperatures (Note 10) 460 600 ms (max)

Quiescent Current (Note 9) SMBus (I

C) Inactive 0.500 0.80 mA (max)

D− Source Voltage 0.7 V

Diode Source Current (D+ − D−)=+ 0.65V; high

level 125 µA (max)

60 µA (min)

Low level 15 µA (max)

5µA (min)

T_CRIT_A and INT Output

Saturation Voltage I

OUT

= 3.0 mA 0.4 V (max)

Power-On Reset Threshold On V

input, falling

edge 2.3

1.8 V (max)

V (min)

Local and Remote T_CRIT and

HIGH Default Temperature settings (Note 11) +127 ˚C

LM83

www.national.com 4

Logic Electrical Characteristics

DIGITAL DC CHARACTERISTICS

Unless otherwise noted, these specifications apply for V

=+3.0 to 3.6 Vdc. Boldface limits apply for T

MIN

MAX

;all other limits T

=+25˚C, unless otherwise noted.

Symbol Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

SMBData, SMBCLK

IN(1)

Logical “1” Input Voltage 2.1 V (min)

IN(0)

Logical “0”Input Voltage 0.8 V (max)

IN(HYST)

SMBData and SMBCLK Digital

Input Hysteresis 300 mV

IN(1)

Logical “1” Input Current V

0.005 1.5 µA (max)

IN(0)

Logical “0” Input Current V

= 0 V −0.005 1.5 µA (max)

ADD0, ADD1

IN(1)

Logical “1” Input Voltage V

1.5 V (min)

IN(0)

Logical “0”Input Voltage GND 0.6 V (max)

IN(1)

Logical “1” Input Current V

2µA (max)

IN(0)

Logical “0” Input Current V

=0V -2 µA (max)

ALL DIGITAL INPUTS

Input Capacitance 20 pF

ALL DIGITAL OUTPUTS

High Level Output Current V

100 µA (max)

SMBus Low Level Output

Voltage I

=3mA

=6mA 0.4

0.6 V (max)

LM83

www.national.com5

Logic Electrical Characteristics (Continued)

SMBus DIGITAL SWITCHING CHARACTERISTICS

Unless otherwise noted, these specifications apply for V

=+3.0 Vdc to +3.6 Vdc, C

(load capacitance) on output lines = 80

pF. Boldface limits apply for T

MIN

to T

MAX

;all other limits T

= +25˚C, unless otherwise noted.

The switching characteristics of the LM83 fully meet or exceed the published specifications of the SMBus or I

C bus. The fol-

lowing parameters are the timing relationships between SMBCLK and SMBData signals related to the LM83. They are not the

C or SMBus bus specifications.

Symbol Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

SMB

SMBus Clock Frequency 100

10 kHz (max)

kHz (min)

LOW

SMBus Clock Low Time 10 % to 10 % 1.3

25 µs (min)

ms (max)

LOW

MEXT Cumulative Clock Low Extend Time 10 ms (max)

HIGH

SMBus Clock High Time 90 % to 90% 0.6 µs (min)

R,SMB

SMBus Rise Time 10% to 90% 1 µs (max)

F,SMB

SMBus Fall Time 90% to 10% 0.3 ns (max)

Output Fall Time C

= 400 pF,

=3mA 250 ns (max)

TIMEOUT

SMBData and SMBCLK Time Low for

Reset of Serial Interface (Note 12) 25

40 ms (min)

ms (max)

SMBCLK (Clock) Period 10 µs (min)

SU;DAT

Data In Setup Time to SMBCLK High 100 ns (min)

HD;DAT

Data Out Stable after SMBCLK Low 300

TBD ns (min)

ns (max)

HD;STA

SMBData Low Setup Time to SMBCLK

Low 100 ns (min)

SU;STO

SMBData High Delay Time after

SMBCLK High (Stop Condition Setup) 100 ns (min)

SU;STA

SMBus Start-Condition Setup Time 0.6 µs (min)

BUF

SMBus Free Time 1.3 µs (min)

SMBus Communication

DS101058-4

LM83

www.national.com 6

Logic Electrical Characteristics (Continued)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions.

Note 2: When the input voltage (VI) at any pin exceeds the power supplies (VI<GND or VI>VCC), the current at that pin should be limited to 5 mA. The 20 mA

maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.

Parasitic components and or ESD protection circuitry are shown in the figure below for the LM83’s pins. The nominal breakdown voltage of the zener D3 is 6.5 V.

Care should be taken not to forward bias the parasitic diode, D1, present on pins: D+, D−,ADD1 andADD0. Doing so by more than 50 mV may corrupt a temperature

or voltage measurement.

Pin Name D1 D2 D3 D4 Pin Name D1 D2 D3 D4

T_CRIT_A & INT x

x SMBData x x

D+ x x x NC (pins9&15) x x x

D− xxxx SMBCLK x x

ADD0, ADD1 x x x NC (pin 13) x x

Note: An x indicates that the diode exists.

Note 3: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National Semicon-

ductor Linear Data Book for other methods of soldering surface mount devices.

Note 4: Human body model, 100 pF discharged through a 1.5 kΩresistor. Machine model, 200 pF discharged directly into each pin.

Note 5: Thermal resistance of the QSOP-16 package is xyz˚C/W, junction-to-ambient when attached to a printed circuit board with 2 oz. foil as shown in

Figure 3

SMBus TIMEOUT

DS101058-7

See drawing DS10105807

DS101058-13

FIGURE 1. ESD Protection Input Structure

LM83

www.national.com7

Logic Electrical Characteristics (Continued)

Note 6: Typicals are at TA= 25˚C and represent most likely parametric norm.

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: The Temperature Error will vary less than ±1.0 ˚C for a variation in VCC of3Vto3.6Vfrom the nominal of 3.3 V.

Note 9: Quiescent current will not increase substantially with an active SMBus.

Note 10: This specification is provided only to indicate how often temperature data is updated. The LM83 can be read at any time without regard to conversion state

(and will yield last conversion result).

Note 11: Default values set at power up.

Note 12: Holding the SMBData and/or SMBCLK lines Low for a time interval greater than tTIMEOUT will cause the LM83 to reset SMBData and SMBCLK to the IDLE

state of an SMBus communication (SMBCLK and SMBData set High).

1.0 Functional Description

The LM83 temperature sensor incorporates a band-gap type

temperature sensor using a Local or three Remote diodes

and an 8-bit ADC (Delta-Sigma Analog-to-Digital Converter).

The LM83 is compatible with the serial SMBus and I

C two

wire interfaces. Digital comparators compare Local (LT) and

Remote (D1RT, D2RT and D3RT) temperature readings to

user-programmable setpoints (LHS, D1RHS, D2RHS,

D3RHS and TCS).Activation of the INT output indicates that

a comparison is greater than the limit preset in a HIGH reg-

ister. The T_CRIT setpoint (TCS) interacts with all the tem-

perature readings. Activation of the T_CRIT_A output indi-

cates that any or all of the temperature readings have

exceed the T_CRIT setpoint.

1.1 CONVERSION SEQUENCE

The LM83 converts its own temperature as well as 3 remote

diode temperatures in the following sequence:

1. Local Temperature (LT)

1. Remote Diode 2 (D2RT)

2. Remote Diode 1 (D1RT)

3. Remote Diode 3 (D3RT)

This round robin sequence takes approximately 480 ms to

complete as each temperature is digitized in approximately

120 ms.

1.2 INT OUTPUT and T_HIGH LIMITS

Each temperature reading (LT, D1RT, D2RT, and D3RT) is

associated with a T_HIGH setpoint register (LHS, D1RHS,

D2RHS, D3RHS).At the end of a temperature reading a digi-

tal comparison determines whether that reading has exceed

its HIGH setpoint. If the temperature reading is greater than

the HIGH setpoint, a bit is set in one of the Status Registers,

to indicate which temperature reading, and the INT output is

activated.

Local and remote temperature diodes are sampled in se-

quence by the A/D converter. The INT output and the Status

DS101058-5

FIGURE 2. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)

DS101058-24

FIGURE 3. Printed Circuit Board Used for Thermal Resistance Specifications

LM83

www.national.com 8

1.0 Functional Description (Continued)

which occurs approximately 60 ms after a temperature diode

is sampled. INT is deactivated when the Status Register,

containing the set bit, is read and a temperature reading is

less than or equal to it’s corresponding HIGH setpoint, as

shown in

Figure 4

Figure 5

shows a simplified logic diagram

for the INT output and related circuitry.

The INT output can be disabled by setting the INT mask bit,

D7, of the configuration register. INT can be programmed to

be active high or low by the state of the INT inversion bit, D1,

in the configuration register. A “0” would program INT to be

active low. INT is an open-drain output.

1.3 T_CRIT_A OUTPUT and T_CRIT LIMIT

T_CRIT_A is activated when any temperature reading is

greater than the limit preset in the critical temperature set-

point register (T_CRIT), as shown in

Figure 6

. The Status

Registers can be read to determine which event caused the

alarm. A bit in the Status Registers is set high to indicate

which temperature reading exceeded the T_CRIT setpoint

temperature and caused the alarm, see

Section 2.3

Local and remote temperature diodes are sampled in se-

quence by the A/D converter. The T_CRIT_A output and the

Status Register flags are updated at the completion of a con-

version. T_CRIT_A and the Status Register flags are reset

only after the Status Register is read and if a temperature

conversion is below the T_CRITsetpoint, as shown in

Figure

Figure 7

shows a simplified logic diagram of the

T_CRIT_A and related circuitry.

Located in the Configuration Register are the mask bits for

each temperature reading, see

Section 2.5

. When a mask bit

is set, its corresponding status flag will not propagate to the

T_CRIT_A output, but will still be set in the Status Registers.

Setting all four mask bits or programming the T_CRIT set-

point to 127˚C will disable the T_CRIT_A output.

1.4 POWER ON RESET DEFAULT STATES

LM83 always powers up to these known default states:

1. Command Register set to 00h

2. Local Temperature set to 0˚C

DS101058-14

*Note: Status Register Bits are reset by a read of Status Register where

bit is located.

FIGURE 4. INT Temperature Response Diagram with

D2RHS and D3RHS set to 127˚C.

DS101058-21

FIGURE 5. INT output related circuitry logic diagram

DS101058-6

*Note: Status Register Bits are reset by a read of Status Register where

bit is located.

FIGURE 6. T_CRIT_A Temperature Response Diagram

with remote diode 1 and local temperature masked.

DS101058-20

FIGURE 7. T_CRIT_A output related circuitry logic

diagram

LM83

www.national.com9

1.0 Functional Description (Continued)

3. Diode 1, Diode 2, and Diode 3 Remote Temperature set

to 0˚C until the LM83 senses a diode present between

the D+ and D− input pins.

4. Status Registers 1 and 2 set to 00h.

5. Configuration Register set to 00h; INT enabled and all

T_CRIT setpoints enabled to activate T_CRIT_A.

6. Local and all Remote T_CRIT set to 127˚C

1.5 SMBus INTERFACE

The LM83 operates as a slave on the SMBus, so the

SMBCLK line is an input (no clock is generated by the LM83)

and the SMBData line is bi-directional. According to SMBus

specifications, the LM83 has a 7-bit slave address. Bit 4 (A3)

of the slave address is hard wired inside the LM83 to a 1.

The remainder of the address bits are controlled by the state

of the address select pins ADD1 and ADD0, and are set by

connecting these pins to ground for a low, (0) , to V

for a

high, (1), or left floating (TRI-LEVEL).

Therefore, the complete slave address is:

A6 A5 A4 1 A2 A1 A0

MSB LSB

and is selected as follows:

Address Select Pin State LM83 SMBus

Slave Address

ADD0 ADD1 A6:A0 binary

0 0 001 1000

0 TRI-LEVEL 001 1001

0 1 001 1010

TRI-LEVEL 0 010 1001

TRI-LEVEL TRI-LEVEL 010 1010

TRI-LEVEL 1 010 1011

1 0 100 1100

1 TRI-LEVEL 100 1101

1 1 100 1110

The LM83 latches the state of the address select pins during

the first read or write on the SMBus. Changing the state of

the address select pins after the first read or write to any de-

vice on the SMBus will not change the slave address of the

LM83.

1.6 TEMPERATURE DATA FORMAT

Temperature data can be read from the Local and Remote

Temperature, T_CRIT, and HIGH setpoint registers; and writ-

ten to the T_CRIT and HIGH setpoint registers. Temperature

data is represented by an 8-bit, two’s complement byte with

an LSB (Least Significant Bit) equal to 1˚C:

Temperature Digital Output

Binary Hex

+125˚C 0111 1101 7Dh

+25˚C 0001 1001 19h

+1˚C 0000 0001 01h

0˚C 0000 0000 00h

−1˚C 1111 1111 FFh

−25˚C 1110 0111 E7h

−55˚C 1100 1001 C9h

1.7 OPEN-DRAIN OUTPUTS

The SMBData, INT and T_CRIT_A outputs are open-drain

outputs and do not have internal pull-ups. A “high” level will

not be observed on these pins until pull-up current is pro-

vided from some external source, typically a pull-up resistor.

Choice of resistor value depends on many system factors

but, in general, the pull-up resistor should be as large as

possible. This will minimize any internal temperature reading

errors due to internal heating of the LM83. The maximum re-

sistance of the pull up, based on LM83 specification for High

Level Output Current, to provide a 2.1V high level, is 30kΩ.

1.8 DIODE FAULT DETECTION

Before each external conversion the LM83 goes through an

external diode fault detection sequence. If a D+ input is

shorted to V

or floating then the temperature reading will

be +127 ˚C, and its OPEN bit in the Status Register will be

set. If the T_CRIT setpoint is set to less than +127 ˚C then

the D+ inputs RTCRIT bit in the Status Register will be set

which will activate the T_CRIT_A output, if enabled. If a D+

is shorted to GND or D−, its temperature reading will be 0 ˚C

and its OPEN bit in the Status Register will not be set.

LM83

www.national.com 10

1.0 Functional Description (Continued)

1.9 COMMUNICATING with the LM83

There are 19 data registers in the LM83, selected by the

Command Register. At power-up the Command Register is

set to “00”, the location for the Read Local Temperature Reg-

ister. The Command Register latches the last location it was

set to. Reading the Status Register resets T_CRIT_A and

INT, so long as a temperature comparison does not signal a

fault (see

Sections 1.2 and 1.3

). All other registers are pre-

defined as read only or write only. Read and write registers

with the same function contain mirrored data.

AWrite to the LM83 will always include the address byte and

the command byte. A write to any register requires one data

byte.

Reading the LM83 can take place either of two ways:

1. If the location latched in the Command Register is cor-

rect (most of the time it is expected that the Command

isters because that will be the data most frequently read

from the LM83), then the read can simply consist of an

address byte, followed by retrieving the data byte.

2. If the Command Register needs to be set, then an ad-

dress byte, command byte, repeat start, and another ad-

dress byte will accomplish a read.

The data byte has the most significant bit first. At the end of

a read, the LM83 can accept either Acknowledge or No Ac-

knowledge from the Master (No Acknowledge is typically

used as a signal for the slave that the Master has read its

last byte).

1.10 SERIAL INTERFACE ERROR RECOVERY

The LM83 SMBus lines will be reset to the SMBus idle state

if the SMBData or SMBCLK lines are held low for 40 ms or

more (t

TIMEOUT

). The LM83 may or may not reset the state of

DS101058-9

LM83

www.national.com11

1.0 Functional Description (Continued)

the serial interface logic if either of the SMBData or SMBCLK

lines are held low between 25 ms and 40 ms. TIMEOUT al-

lows a clean recovery in cases where the master may be re-

set while the LM83 is transmitting a low bit thus preventing

possible bus lock up.

Whenever the LM83 sees the start condition its serial inter-

face will reset to the beginning of the communication, thus

the LM83 will expect to see an address byte next. This sim-

plifies recovery when the master is reset while the LM83 is

transmitting a high.

LM83

www.national.com 12

1.0 Functional Description (Continued)

2.0 LM83 REGISTERS

2.1 COMMAND REGISTER

Selects which registers will be read from or written to. Data for this register should be transmitted during the Command Byte of

the SMBus write communication.

P7 P6 P5 P4 P3 P2 P1 P0

0 Command Select

P0-P7: Command Select

Command Se-

lect Address Power On Default State Register Name Register Function

<P7:P0>hex <D7:D0>binary <D7:D0>deci-

mal

00h 0000 0000 0 RLT Read Local Temperature

01h 0000 0000 0 RD2RT Read D2 Remote

Temperature

02h 0000 0000 0 RSR1 Read Status Register 1

03h 0000 0000 0 RC Read Configuration

04h 0000 0000 0 Reserved

05h 0111 1111 127 RLHS Read Local HIGH Setpoint

06h Reserved

07h 0111 1111 127 RD2RHS Read D2 Remote HIGH

Setpoint

08h Reserved

09h 0000 0000 WC Write Configuration

0Ah Reserved

0Bh 0111 1111 127 WD2LHS Write Local HIGH Setpoint

0Ch Reserved

0Dh 0111 1111 127 WD2RHS Write D2 Remote HIGH

Setpoint

0Eh-2Fh Reserved for Future Use

30h 0000 0000 0 RD1RT Read D1 Remote

Temperature

31h 0000 0000 0 RD3RT Read D3 Remote

Temperature

32h-34h Reserved for Future Use

35h 0000 0000 0 RSR2 Read Status Register 2

36h-37h Reserved for Future Use

38h 0111 1111 127 RD1RHS Read D1 Remote HIGH

Setpoint

39h Reserved for Future Use

3Ah 0111 1111 127 RD3RHS Read D3 Remote HIGH

Setpoint

3Bh-41h Reserved for Future Use

42h 0111 1111 127 RTCS Read T_CRIT Setpoint

43h-4Fh Reserved for Future Use

50h 0111 1111 127 WD1RHS Write D1 Remote HIGH

Setpoint

51h Reserved for Future Use

52h 0111 1111 127 WD3RHS Write D3 Remote HIGH

Setpoint

53h-59h Reserved for Future Use

5Ah 0111 1111 127 WTCS Write T_CRIT Setpoint

LM83

www.national.com13

1.0 Functional Description (Continued)

Command Se-

lect Address Power On Default State Register Name Register Function

<P7:P0>hex <D7:D0>binary <D7:D0>deci-

mal

5Ch-6Fh and

F0h-FDh Reserved for Future Use

FEh 0000 0001 1 RMID Read Manufacturers ID

FFh RSR Read Stepping or Die

Revision Code

2.2 LOCAL and D1, D2 and D3 REMOTE TEMPERATURE REGISTERS (LT, D1RT, D2RT, and D3RT)

(Read Only Address 00h, 01h, 30h and 31h):

D7 D6 D5 D4 D3 D2 D1 D0

MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

D7–D0: Temperature Data. One LSB = 1˚C. Two’s complement format.

2.3 STATUS REGISTERS 1 and 2

2.3.1 Status Register 1 (SR1) (Read Only Address 02h):

D7 D6 D5 D4 D3 D2 D1 D0

0 LHIGH 0 D2RHIGH 0 D2OPEN D2CRIT LCRIT

Power up default is with all bits “0” (zero).

D0: LCRIT: When set to a 1 indicates an Local Critical Temperature alarm.

D1: D2CRIT: When set to a 1 indicates a Remote Diode 2 Critical Temperature alarm.

D2: D2OPEN: When set to 1 indicates a Remote Diode 2 disconnect.

D4: D2RHIGH: When set to 1 indicates a Remote Diode 2 HIGH Temperature alarm.

D6: LHIGH: When set to 1 indicates a Local HIGH Temperature alarm.

D7, D5, and D3: These bits are always set to 0 and reserved for future use.

Status Register 2

2.3.2 Status Register 2 (SR2) (Read Only Address 35h):

D7 D6 D5 D4 D3 D2 D1 D0

D1RHIGH 0 D1OPEN D3RHIGH 0 D3OPEN D3CRIT D1CRIT

Power up default is with all bits “0” (zero).

D0: D1CRIT, when set to 1 indicates a Remote Diode 1 Critical Temperature alarm.

D1: D3CRIT, when set to 1 indicates a Remote Diode 3 Critical Temperature alarm.

D2: D3OPEN, when set to 1 indicates a Remote Diode 3 disconnect.

D4: D3RHIGH, when set to 1 indicates a Remote Diode 3 HIGH Temperature alarm.

D5: D1OPEN, when set to 1 indicates a Remote Diode 1 disconnect.

D7: D1RHIGH, when set to 1 indicates a Remote Diode 1

HIGH Temperature alarm.

D6, and D3: These bits are always set to 0 and reserved for future use.

2.4 MANUFACTURERS ID REGISTER

(Read Address FEh) Default value 01h.

2.5 CONFIGURATION REGISTER

(Read Address 03h/Write Address 09h):

D7 D6 D5 D4 D3 D2 D1 D0

INT mask 0D1

T_CRIT_A

mask

T_CRIT_A

mask

T_CRIT_A

mask

Local

T_CRIT_A

mask

INT Inversion 0

Power up default is with all bits “0” (zero).

D7: INT mask: When set to 1 INT interrupts are masked.

LM83

www.national.com 14

1.0 Functional Description (Continued)

D5: T_CRIT mask for Diode 1, when set to 1 a Diode 1 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D4: T_CRIT mask for Diode 2, when set to 1 a Diode 2 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D3: T_CRIT mask for Diode 3, when set to 1 a Diode 3 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D2: T_CRIT mask for Local reading, when set to 1 a Local temperature reading that exceeds T_CRIT setpoint will not activate

the T_CRIT_A pin.

D1: INT active state inversion. When INT Inversion is set to a 1 the active state of the INT output will be a logical high.Alow would

then select an active state of a logical low.

D6 and D0: These bits are always set to 0 and reserved for future use. A write of 1 will return a 0 when read.

2.6 LOCAL, DIODE 1, DIODE 2 and DIODE 3 HIGH SETPOINT REGISTERS (LHS, D1RHS, D2RHS and D3RHS)

(Read Address 05h, 07h, 38h, 3Ah /Write Address 0Bh, 0Dh,

50h, 52h):

D7 D6 D5 D4 D3 D2 D1 D0

MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

D7–D0: HIGH setpoint temperature data. Power up default is LHIGH = RD1HIGH=RD2HIGH=RD3HIGH = 127˚C.

2.7 T_CRIT REGISTER (TCS)

(Read Address 42h/Write Address 5Ah):

D7 D6 D5 D4 D3 D2 D1 D0

MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

D7–D0: T_CRIT setpoint temperature data. Power up default is T_CRIT = 127˚C.

LM83

www.national.com15

3.0 SMBus Timing Diagrams

DS101058-10

(a) Serial Bus Write to the internal Command Register followed by a the Data Byte

DS101058-11

(b) Serial Bus Write to the internal Command Register

DS101058-12

FIGURE 8. Serial Bus Timing Diagrams

LM83

www.national.com 16

4.0 Application Hints

The LM83 can be applied easily in the same way as other

integrated-circuit temperature sensors, and its remote diode

sensing capability allows it to be used in new ways as well.

It can be soldered to a printed circuit board, and because the

path of best thermal conductivity is between the die and the

pins, its temperature will effectively be that of the printed cir-

cuit board lands and traces soldered to the LM83’s pins. This

presumes that the ambient air temperature is almost the

same as the surface temperature of the printed circuit board;

if the air temperature is much higher or lower than the sur-

face temperature, the actual temperature of the of the LM83

die will be at an intermediate temperature between the sur-

face and air temperatures. Again, the primary thermal con-

duction path is through the leads, so the circuit board tem-

perature will contribute to the die temperature much more

strongly than will the air temperature.

To measure temperature external to the LM83’s die, use a

remote diode. This diode can be located on the die of a tar-

get IC, allowing measurement of the IC’s temperature, inde-

pendent of the LM83’s temperature. The LM83 has been op-

timized to measure the remote diode of a Pentium II

processor as shown in

Figure 9

.Adiscrete diode can also be

used to sense the temperature of external objects or ambient

air. Remember that a discrete diode’s temperature will be af-

fected, and often dominated, by the temperature of its leads.

Most silicon diodes do not lend themselves well to this appli-

cation. It is recommended that a 2N3904 transistor base

emitter junction be used with the collector tied to the base.

A diode connected 2N3904 approximates the junction avail-

able on a Pentium microprocessor for temperature measure-

ment. Therefore, the LM83 can sense the temperature of this

diode effectively.

3.1 ACCURACY EFFECTS OF DIODE NON-IDEALITY

FACTOR

The technique used in today’s remote temperature sensors

is to measure the change in V

at two different operating

points of a diode. For a bias current ratio of N:1, this differ-

ence is given as:

where:

•ηis the non-ideality factor of the process the diode is

manufactured on,

•q is the electron charge,

•k is the Boltzmann’s constant,

•N is the current ratio,

•T is the absolute temperature in ˚K.

The temperature sensor then measures ∆V

and converts

to digital data. In this equation, k and q are well defined uni-

versal constants, and N is a parameter controlled by the tem-

perature sensor. The only other parameter is η, which de-

pends on the diode that is used for measurement. Since

∆V

is proportional to both ηand T, the variations in ηcan-

not be distinguished from variations in temperature. Since

the non-ideality factor is not controlled by the temperature

sensor, it will directly add to the inaccuracy of the sensor. For

the Pentium II Intel specifies a ±1% variation in ηfrom part

to part. As an example, assume a temperature sensor has

an accuracy specification of ±3 ˚C at room temperature of 25

˚C and the process used to manufacture the diode has a

non-ideality variation of ±1%. The resulting accuracy of the

temperature sensor at room temperature will be:

ACC

=±3˚C+(

1% of 298 ˚K) = ±6 ˚C.

The additional inaccuracy in the temperature measurement

caused by η, can be eliminated if each temperature sensor is

calibrated with the remote diode that it will be paired with.

3.2 PCB LAYOUT for MINIMIZING NOISE

In a noisy environment, such as a processor mother board,

layout considerations are very critical. Noise induced on

traces running between the remote temperature diode sen-

sor and the LM83 can cause temperature conversion errors.

The following guidelines should be followed:

1. Place a 0.1 µF power supply bypass capacitor as close

as possible to the V

pin and the recommended 2.2 nF

capacitor as close as possible to the D+ and D− pins.

Make sure the traces to the 2.2nF capacitor are

matched.

2. The recommended 2.2nF diode bypass capacitor actu-

ally has a range of 200pF to 3.3nF. The average tem-

perature accuracy will not degrade. Increasing the ca-

pacitance will lower the corner frequency where

differential noise error affects the temperature reading

thus producing a reading that is more stable. Con-

versely, lowering the capacitance will increase the cor-

ner frequency where differential noise error affects the

temperature reading thus producing a reading that is

less stable.

3. Ideally, the LM83 should be placed within 10cm of the

Processor diode pins with the traces being as straight,

short and identical as possible. Trace resistance of 1Ω

can cause as much as 1˚C of error.

4. Diode traces should be surrounded by a GND guard ring

to either side, above and below if possible. This GND

guard should not be between the D+ and D− lines. In the

event that noise does couple to the diode lines it would

be ideal if it is coupled common mode. That is equally to

the D+ and D− lines.(See

Figure 10

)

5. Avoid routing diode traces in close proximity to power

supply switching or filtering inductors.

DS101058-15

Pentium or 3904 Temperature vs LM83 Temperature

Reading

LM83

www.national.com17

4.0 Application Hints (Continued)

6. Avoid running diode traces close to or parallel to high

speed digital and bus lines. Diode traces should be kept

at least 2cm. apart from the high speed digital traces.

7. If it is necessary to cross high speed digital traces, the

diode traces and the high speed digital traces should

cross at a 90 degree angle.

8. The ideal place to connect the LM83’s GND pin is as

close as possible to the Processors GND associated

with the sense diode. For the Pentium II this would be

pin A14.

9. Leakage current between D+ and GND should be kept

to a minimum. One nano-ampere of leakage can cause

as much as 1˚C of error in the diode temperature read-

ing. Keeping the printed circuit board as clean as pos-

sible will minimize leakage current.

Noise coupling into the digital lines greater than 300mVp-p

(typical hysteresis), overshoot greater than 500mV above

, and undershoot less than 500mV below GND, may pre-

vent successful SMBus communication with the LM83. SM-

Bus no acknowledge is the most common symptom, causing

unnecessary traffic on the bus. Although, the SMBus maxi-

mum frequency of communication is rather low (100kHz

max) care still needs to be taken to ensure proper termina-

tion within a system with multiple parts on the bus and long

printed circuit board traces. An R/C lowpass filter with a 3db

corner frequency of about 40MHz has been included on the

LM83’s SMBCLK input. Additional resistance can be added

in series with the SMBData and SMBCLK lines to further

help filter noise and ringing. Minimize noise coupling by

keeping digital traces out of switching power supply areas as

well as ensuring that digital lines containing high speed data

communications cross at right angles to the SMBData and

SMBCLK lines.

4.0 Typical Applications

DS101058-17

FIGURE 10. Ideal Diode Trace Layout

DS101058-22

FIGURE 11. LM83 Demo Board Diode Layout

LM83

www.national.com 18

4.0 Typical Applications (Continued)

DS101058-23

Any two or three D+ inputs can be connected in parallel to increase the number of High temperature setpoints for a particular temperature reading. If all three

D+ inputs are tied as shown here, D1+, D2+ and D3+ temperature readings will be identical, unless affected by PCB D+ trace resistance differences.

FIGURE 12. Connecting all Three LM83 Diode Inputs in Parallel will Increase the Number of HIGH Setpoints for a

Single Temperature Reading to Three.

LM83

www.national.com19

Physical Dimensions inches (millimeters) unless otherwise noted

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL

COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or

systems which, (a) are intended for surgical implant

into the body, or (b) support or sustain life, and

whose failure to perform when properly used in

accordance with instructions for use provided in the

labeling, can be reasonably expected to result in a

significant injury to the user.

2. A critical component is any component of a life

support device or system whose failure to perform

can be reasonably expected to cause the failure of

the life support device or system, or to affect its

safety or effectiveness.

National Semiconductor

Corporation

Americas

Tel: 1-800-272-9959

Fax: 1-800-737-7018

Email: support@nsc.com

National Semiconductor

Europe Fax: +49 (0) 180-530 85 86

Email: europe.support@nsc.com

Deutsch Tel: +49 (0) 69 9508 6208

English Tel: +44 (0) 870 24 0 2171

Français Tel: +33 (0) 1 41 91 8790

National Semiconductor

Asia Pacific Customer

Response Group

Tel: 65-2544466

Fax: 65-2504466

Email: ap.support@nsc.com

National Semiconductor

Japan Ltd.

Tel: 81-3-5639-7560

Fax: 81-3-5639-7507

www.national.com

16-Lead QSOP Package

Order Number LM83CIMQA or LM83CIMQAX

NS Package Number MQA16

LM83 Triple-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

IMPORTANT NOTICE

Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,

and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should

obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are

sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.

TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard

warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where

mandated by government requirements, testing of all parameters of each product is not necessarily performed.

TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and

applications using TI components. To minimize the risks associated with customer products and applications, customers should provide

adequate design and operating safeguards.

TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,

or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information

published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a

warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual

property of the third party, or a license from TI under the patents or other intellectual property of TI.

Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied

by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive

business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional

restrictions.

Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all

express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not

responsible or liable for any such statements.

TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably

be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing

such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and

acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products

and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be

provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in

such safety-critical applications.

TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are

specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military

specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at

the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.

TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are

designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated

products in automotive applications, TI will not be responsible for any failure to meet such requirements.

Following are URLs where you can obtain information on other Texas Instruments products and application solutions:

Products Applications

Audio www.ti.com/audio Communications and Telecom www.ti.com/communications

Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers

Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps

DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy

DSP dsp.ti.com Industrial www.ti.com/industrial

Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical

Interface interface.ti.com Security www.ti.com/security

Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense

Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive

Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video

RFID www.ti-rfid.com

OMAP Mobile Processors www.ti.com/omap

Wireless Connectivity www.ti.com/wirelessconnectivity

TI E2E Community Home Page e2e.ti.com

Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265