LM89-1CIM

LM89 NSC | Alldatasheet

Document overview

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Technical content

Features

n Accurately senses die temperature of remote ICs or diode junctions n Offset register allows sensing a variety of thermal diodes accurately n On-board local temperature sensing n 10 bit plus sign remote diode temperature data format, 0.125 ˚C resolution n T_CRIT_A output useful for system shutdown n ALERT output supports SMBus 2.0 protocol n SMBus 2.0 compatible interface, supports TIMEOUT n 8-pin MSOP and SOIC packages Key Specifications j Supply Voltage 3.0 V to 3.6 V j Supply Current 0.8 mA (typ) j Local Temp Accuracy (includes quantization error) TA=25˚C to 125˚C ±3.0 ˚C (max) j Remote Diode Temp Accuracy (includes quantization error) TA=30˚C,TD=80˚C ±0.75 ˚C (max) TA=30˚C to 50˚C, TD=60˚C to 100˚C ±1.0 ˚C (max) TA=0˚C to 85˚C, TD=25˚C to 125˚C ±3.0 ˚C (max)

Applications

n Processor/Computer System Thermal Management (e.g. Laptop, Desktop, Workstations, Server) n Electronic Test Equipment n Office Electronics Simplified Block Diagram 20041501 Pentium™ is a trademark of Intel Corporation. December 2004 LM89±0.75˚C Accurate, Remote Diode and Local Digital Temperature Sensor with Two-Wire Interface © 2004 National Semiconductor Corporation DS200415 www.national.com

Ordering Information

LM89CIMM T15C MUA08A (MSOP-8) 1000 Units onTape and Reel LM89-1CIMM T19C MUA08A (MSOP-8) 1000 Units onTape and Reel LM89CIMMX T15C MUA08A (MSOP-8) 3500 Units on Tape and Reel LM89-1CIMMX T19C MUA08A (MSOP-8) 3500 Units on Tape and Reel LM89CIM LM89CIM M08A (SOIC-8) 95 Units in Rail LM89-1CIM LM89-1CIM M08A (SOIC-8) 95 Units in Rail LM89CIMX LM89CIM M08A (SOIC-8) 2500 Units on Tape and Reel LM89-1CIMX LM89-1CIM M08A (SOIC-8) 2500 Units on Tape and Reel Pin Descriptions Label Pin # Function Typical Connection VDD 1 Positive Supply Voltage Input DC Voltage from 3.0 V to 3.6 V. VDD should be bypassed with a 0.1µF capacitor in parallel with 100pF. The 100pF capacitor should be placed as close as possible to the power supply pin. A bulk capacitance of approximately 10µF needs to be in the near vicinity to the LM89 V DD. D+ 2 Diode Current Source To Diode Anode. Connected to remote discrete diode-connected transistor junction or to the diode-connected transistor junction on a remote IC whose die temperature is being sensed. A 2.2 nF diode bypass capacitor is required to filter high frequency noise. Place the 2.2 nF capacitor between and as close as possible to the LM89’s D+ and D− pins. Make sure the traces to the 2.2 nF capacitor are matched. D− 3 Diode Return Current Sink To Diode Cathode. T_CRIT_A

4 T_CRIT Alarm Output,

Open-Drain, Active-Low Pull-Up Resistor, Controller Interrupt or Power Supply Shutdown Control GND 5 Power Supply Ground Ground ALERT 6 Interrupt Output, Open-Drain, Active-Low Pull-Up Resistor, Controller Interrupt or Alert Line SMBData 7 SMBus Bi-Directional Data Line, Open-Drain Output From and to Controller, Pull-Up Resistor SMBCLK 8 SMBus Input From Controller, Pull-Up Resistor LM89 www.national.com 2

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Absolute Maximum Ratings(Note 1) Supply Voltage −0.3 V to 6.0 V Voltage at SMBData, SMBCLK, ALERT, T_CRIT_A −0.5V to 6.0V Voltage at Other Pins −0.3 V to (VDD + 0.3 V) D− Input Current ±1m A Input Current at All Other Pins (Note 2) ±5m A Package Input Current (Note 2) 30 mA SMBData, ALERT, T_CRIT_A Output Sink Current 10 mA Storage Temperature −65˚C to +150˚C Soldering Information, Lead Temperature SOIC-8 or MSOP-8 Packages (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) Operating Temperature Range 0˚C to +125˚C

Electrical Characteristics

Temperature Range T MIN≤TA≤TMAX LM89 0˚C ≤TA≤+85˚C Supply Voltage Range (VDD) +3.0V to +3.6V Temperature-to-Digital Converter Characteristics Unless otherwise noted, these specifications apply for VDD=+3.0Vdc to 3.6Vdc.Boldface limits apply for TA =T J = TMIN≤TA≤TMAX; all other limits TA=T J=+25˚C, unless otherwise noted. Parameter Conditions Typical Limits Units (Note 6) (Note 7) (Limit) Temperature Error Using Local Diode T A = +25˚C to +125˚C, (Note 8) ±1 ±3 ˚C (max) Temperature Error Using Remote Diode of 0.13 micron Pentium 4 with typical non-ideality of 1.0021 and series R= 3.64Ω. For other processors email hardware.monitor.team @nsc.com to obtain the latest data. (TD is the Remote Diode Junction Temperature) TA = +30˚C T D = +80˚C ±0.75 ˚C (max) TA = +30˚C to +50˚C TD = +60˚C to +100˚C ±1 ˚C (max) TA = +0˚C to +85˚C TD = +25˚C to +125˚C ±3 ˚C (max) Remote Diode Measurement Resolution 11 Bits 0.125 ˚C Local Diode Measurement Resolution 8 Bits 1˚ C Conversion Time of All Temperatures at the Fastest Setting (Note 10) 31.25 34.4 ms (max) Quiescent Current (Note 9) SMBus Inactive, 16Hz conversion rate 0.8 1.7 mA (max) Shutdown 315 µA D− Source Voltage 0.7 V Diode Source Current (D+ − D−)=+ 0.65V; high level 160 315 µA (max) 110 µA (min) Low level 13 20 µA (max) 7 µA (min) ALERT and T_CRIT_A Output Saturation Voltage IOUT = 6.0 mA 0.4 V (max) Power-On Reset Threshold Measure on V DD input, falling edge 2.4 1.8 V (max) V (min) Local and Remote HIGH Default Temperature settings (Note 11) +70 ˚C Local and Remote LOW Default Temperature settings (Note 11) 0 ˚C Local T_CRIT Default Temperature Setting (Note 11) +85 ˚C LM89 www.national.com 4

Temperature-to-Digital Converter Characteristics (Continued) Unless otherwise noted, these specifications apply for VDD=+3.0Vdc to 3.6Vdc.Boldface limits apply for TA =T J = TMIN≤TA≤TMAX; all other limits TA=T J=+25˚C, unless otherwise noted. Parameter Conditions Typical Limits Units (Note 6) (Note 7) (Limit) Remote T_CRIT Default Temperature Setting (Note 11) +110 ˚C Logic Electrical Characteristics DIGITAL DC CHARACTERISTICSUnless otherwise noted, these specifications apply for VDD=+3.0 to 3.6 Vdc.Boldface lim- its apply for TA =T J =T MIN to TMAX; all other limits TA=T J=+25˚C, unless otherwise noted. Symbol Parameter Conditions Typical Limits Units (Note 6) (Note 7) (Limit) SMBData, SMBCLK INPUTS V IN(1) Logical “1” Input Voltage 2.1 V (min) VIN(0) Logical “0”Input Voltage 0.8 V (max) VIN(HYST) SMBData and SMBCLK Digital Input Hysteresis 400 mV IIN(1) Logical “1” Input Current V IN =V DD 0.005 ±10 µA (max) IIN(0) Logical “0” Input Current V IN = 0 V −0.005 ±10 µA (max) CIN Input Capacitance 5 pF ALL DIGITAL OUTPUTS I OH High Level Output Current V OH =V DD 10 µA (max) VOL SMBus Low Level Output Voltage IOL = 4mA IOL = 6mA 0.4 0.6 V (max) SMBus DIGITAL SWITCHING CHARACTERISTICSUnless otherwise noted, these specifications apply for VDD=+3.0 Vdc to +3.6 Vdc, CL (load capacitance) on output lines = 80 pF.Boldface limits apply for TA =T J =T MIN to TMAX; all other limits TA =T J = +25˚C, unless otherwise noted. The switching characteristics of the LM89 fully meet or exceed the published specifi- cations of the SMBus version 2.0. The following parameters are the timing relationships between SMBCLK and SMBData sig- nals related to the LM89. They adhere to but are not necessarily the SMBus bus specifications. Symbol Parameter Conditions Typical Limits Units (Note 6) (Note 7) (Limit) f SMB SMBus Clock Frequency 100 kHz (max) kHz (min) tLOW SMBus Clock Low Time from V IN(0)max to VIN(0)max 4.7 µs (min) ms (max) tHIGH SMBus Clock High Time from V IN(1)min to VIN(1)min 4.0 µs (min) tR,SMB SMBus Rise Time (Note 12) 1 µs (max) tF,SMB SMBus Fall Time (Note 13) 0.3 µs (max) tOF Output Fall Time C L = 400pF, IO = 3mA, (Note 13) 250 ns (max) tTIMEOUT SMBData and SMBCLK Time Low for Reset of Serial Interface (Note 14) ms (min) ms (max) tSU;DAT Data In Setup Time to SMBCLK High 250 ns (min) tHD;DAT Data Out Stable after SMBCLK Low 300 900 ns (min) ns (max) tHD;STA Start Condition SMBData Low to SMBCLK Low (Start condition hold before the first clock falling edge) 100 ns (min) t SU;STO Stop Condition SMBCLK High to SMBData Low (Stop Condition Setup) 100 ns (min) tSU;STA SMBus Repeated Start-Condition Setup Time, SMBCLK High to SMBData Low 0.6 µs (min) tBUF SMBus Free Time Between Stop and Start Conditions 1.3 µs (min) LM89 www.national.com5

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 > VDD), the current at that pin should be limited to 5 mA. be taken not to forward bias the parasitic diode, D1, present on pins: D+, D−. Doing so by more than 50 mV may corrupt a temperature measurements. Note: An “x” indicates that the diode exists. Note 3: See the URL ”http://www.national.com/packaging/“ for other recommendations and methods of soldering surface mount devices. Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor. Machine model, 200pF discharged directly into each pin. A = 25˚C and represent most likely parametric norm. Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). dissipation of the LM89 and the thermal resistance. See (Note 5) for the thermal resistance to be used in the self-heating calculation. Note 9: Quiescent current will not increase substantially with an SMBus. (and will yield last conversion result). Note 11: Default values set at power up. Note 12: The output rise time is measured from (VIN(0)max + 0.15V) to (VIN(1)min − 0.15V). Note 13: The output fall time is measured from (VIN(1)min - 0.15V) to (VIN(1)min + 0.15V). SMBData and SMBCLK pins to a high impedance state. FIGURE 1. ESD Protection Input Structure

1.0 Functional Description

register or less than the limit preset in a LOW limit register. curs when the temperature is above the T_CRIT setpoint. discussed further in Section 4.1 DIODE NON-IDEALITY. the value placed in the offset registers.

1.1 CONVERSION SEQUENCE

cess the busy bit (D7) in the Status register (02h) is high. supply current as shown inFigure 2.

1.2 THE ALERT OUTPUT

ent only in how the user interacts with the LM89. must be cleared to trigger an ALERT in all modes.

1.2.1 ALERT Output as a Temperature Comparator

be set high. This is not the power-on-default state. FIGURE 2. Conversion Rate Effect on Power Supply

1.0 Functional Description (Continued)

1.2.2 ALERT Output as an Interrupt

ALERT CONFIGURE REGISTER (xBF) must be set low. This is the power-on-default state.

1. Master reads the LM89 STATUS REGISTER to deter-
2. LM89 clears STATUS REGISTER, resets the ALERT
3. Master attends to conditions that caused the ALERT to
4. Master resets the ALERT mask (D7 in the Configuration

1.2.3 ALERT Output as an SMBus ALERT

operation as little as possible. transmission of their address. the LM89 will be fully compatible with all competitive parts. response to an ARA and releasing the ALERT output pin. the end of the interrupt service routine. FIGURE 3. ALERT Comparator Temperature Response FIGURE 4. ALERT Output as an Interrupt Temperature

1. Master Senses SMBus alert line low
2. Master sends a START followed by the Alert Response

Address (ARA) with a Read Command.

1. Alerting Device(s) send ACK.
2. Alerting Device(s) send their Address. While transmitting
3. Master attends to conditions that caused the ALERT to

started, setpoint limits adjusted, etc.

1. Master resets the ALERT mask (D7 in the Configuration

should ever be assigned this address. the LM89 to respond to the ARA command.

1.3 T_CRIT_A OUTPUT and T_CRIT LIMIT

temperature and caused the alarm, see Section 2.3.

1.4 POWER-ON-DEFAULT STATES

LM89 remains in these states until after the first conversion.

1. Command Register set to 00h
2. Local Temperature set to 0˚C
3. Remote Diode Temperature set to 0˚C until the end of
4. Status Register set to 00h.
5. Configuration register set to 00h; ALERT enabled, Re-
6. 85˚C Local T_CRIT temperature setpoint
7. 110˚C Remote T_CRIT temperature setpoint
8. 70˚C Local and Remote HIGH temperature setpoints
9. 0˚C Local and Remote LOW temperature setpoints
10. Filter and Alert Configure Register set to 00h; filter dis-
11. Conversion Rate Register set to 8h; conversion rate set

1.5 SMBus INTERFACE

1.6 TEMPERATURE DATA FORMAT

(T_CRIT, LOW, HIGH) are read/write. FIGURE 5. ALERT Output as an SMBus ALERT FIGURE 6. T_CRIT_A Temperature Response Diagram

available in two 8-bit registers: Temperature Digital Output Binary Hex +125˚C 0111 1101 0000 0000 7D00h +25˚C 0001 1001 0000 0000 1900h +1˚C 0000 0001 0000 0000 0100h +0.125˚C 0000 0000 0010 0000 0020h 0˚C 0000 0000 0000 0000 0000h −0.125˚C 1111 1111 11100000 FFE0h −1˚C 1111 11110000 0000 FF00h −25˚C 1110 0111 0000 0000 E700h −55˚C 1100 1001 0000 0000 C900h Local 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, ALERT 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 provided by some external source, typically a pull-up resis- tor. Choice of resistor value depends on many system fac- tors 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 LM89. The maximum resistance of the pull-up to provide a 2.1V high level, based on LM89 specification for High Level Output Current with the supply voltage at 3.0V, is 82kΩ(5%) or 88.7kΩ(1%).

1.8 DIODE FAULT DETECTION

The LM89 is equipped with operational circuitry designed to detect fault conditions concerning the remote diode. In the event that the D+ pin is detected as shorted to V DD or floating, the Remote Temperature High Byte (RTHB) register is loaded with +127˚C, the Remote Temperature Low Byte (RTLB) register is loaded with 0, and the OPEN bit (D2) in the status register is set. As a result, if the Remote T_CRIT setpoint register (RCS) is set to a value less than +127˚C the ALERT and T_Crit output pins will be pulled low, if the Alert Mask and T_Crit Mask are disabled. If the Remote HIGH Setpoint High Byte Register (RHSHB) is set to a value less than +127˚C then ALERT will be pulled low, if the Alert Mask is disabled. The OPEN bit itself will not trigger and ALERT. In the event that the D+ pin is shorted to ground or D−, the Remote Temperature High Byte (RTHB) register is loaded with −128˚C (1000 0000) and the OPEN bit (D2) in the status register will not be set. Since operating the LM89 at −128˚C is beyond it’s operational limits, this temperature reading represents this shorted fault condition. If the value in the Remote Low Setpoint High Byte Register (RLSHB) is more than −128˚C and the Alert Mask is disabled, ALERT will be pulled low. Remote diode temperature sensors that have been previ- ously released and are competitive with the LM89 output a code of 0˚C if the external diode is short-circuited. This change is an improvement that allows a reading of 0˚C to be truly interpreted as a genuine 0˚C reading and not a fault condition.

1.9 COMMUNICATING WITH THE LM89

The data registers in the LM89 are selected by the Com- mand Register. At power-up the Command Register is set to “00”, the location for the Read Local Temperature Register. The Command Register latches the last location it was set to. Each data register in the LM89 falls into one of four types of user accessibility: 1. Read only 2. Write only 3. Read/Write same address 4. Read/Write different address A Write to the LM89 will always include the address byte and the command byte. A write to any register requires one data byte. Reading the LM89 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 Register will point to one of the Read Temperature Reg- isters because that will be the data most frequently read from the LM89), 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 address byte, command byte, repeat start, and another address byte will accomplish a read. The data byte has the most significant bit first. At the end of a read, the LM89 can accept either acknowledge or No Acknowledge from the Master (No Acknowledge is typically used as a signal for the slave that the Master has read its last byte). It takes the LM89 31.25ms to measure the tem- perature of the remote diode and internal diode. When re- trieving all 10 bits from a previous remote diode temperature measurement, the master must insure that all 10 bits are from the same temperature conversion. This may be achieved by using one-shot mode or by setting the conver- sion rate and monitoring the busy bit such that no conversion occurs in between reading the MSB and LSB of the last temperature conversion. LM89 www.national.com 10

1.10 SERIAL INTERFACE RESET

returned to a known state in the communication protocol.

1. When SMBData is LOW, the LM89 SMBus state ma-

SMBData lines must be held low for at least 35ms.

1. When SMBData is HIGH, have the master initiate an

1.11 DIGITAL FILTER

(c) Serial Bus Read from a Register with the Internal Command Register preset to desired value. FIGURE 7. SMBus Timing Diagrams

Level 2 sets maximum filtering. not induce an offset as shown. FIGURE 8. Filter Output Response to a Step Input FIGURE 9. Digital Filter Response in a Pentium 4 processor System. The filter on and off curves were purposely offset to better show noise performance.

1.12 FAULT QUEUE

Configuration register (09h) to “1”.

1.13 ONE-SHOT REGISTER

is not stored. A zero will always be read from this register.

2.0 LM89 Registers

2.1 COMMAND REGISTER

the SMBus write communication. FIGURE 10. Fault Queue Temperature Response

2.0 LM89 Registers (Continued)

Command Select Address Power-On-Default State Register Name Register Function Read Address <P7:P0> hex Write Address <P7:P0> hex <D7:D0> binary <D7:D0> decimal 12h 12h 0000 0000 0 RTOLB Remote Temperature Offset Low Byte 13h 13h 0000 0000 0 RHSLB Remote HIGH Setpoint Low Byte 14h 14h 0000 0000 0 RLSLB Remote LOW Setpoint Low Byte 19h 19h 0110 1110 110 RCS Remote T_CRIT Setpoint 20h 20h 0101 0101 85 LCS Local T_CRIT Setpoint 21h 21h 0000 1010 10 TH T_CRIT Hysteresis B0h-BEh B0h-BEh Manufacturers Test Registers BFh BFh 0000 0000 0 RDTF Remote Diode Temperature Filter FEh NA 0000 0001 1 RMID Read Manufacturer’s ID FFh NA LM89 0011 0001 LM89-1 0011 0100 RDR Read Stepping or Die Revision Code

2.2 LOCAL and REMOTE TEMPERATURE REGISTERS (LT, RTHB, RTLB)

(Read Only Address 00h, 01h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 For LT and RTHB D7–D0: Temperature Data. LSB = 1˚C. Two’s complement format. (Read Only Address 10h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0.125 00000 For RTLB D7–D5: Temperature Data. LSB = 0.125˚C. Two’s complement format. The maximum value available from the Local Temperature register is 127; the minimum value available from the Local Temperature register is -128. The maximum value available from the Remote Temperature register is 127.875; the minimum value available from the Remote Temperature registers is −128.875.

2.3 STATUS REGISTER (SR)

(Read Only Address 02h): D7 D6 D5 D4 D3 D2 D1 D0 Busy LHIGH LLOW RHIGH RLOW OPEN RCRIT LCRIT Power up default is with all bits “0” (zero). D0: LCRIT: When set to “1” indicates a Local Critical Temperature alarm. D1: RCRIT: When set to “1” indicates a Remote Diode Critical Temperature alarm. D2: OPEN: When set to “1” indicates a Remote Diode disconnect. D3: RLOW: When set to “1” indicates a Remote Diode LOW Temperature alarm D4: RHIGH: When set to “1” indicates a Remote Diode HIGH Temperature alarm. D5: LLOW: When set to “1” indicates a Local LOW Temperature alarm. D6: LHIGH: When set to “1” indicates a Local HIGH Temperature alarm. D7: Busy: When set to “1” ADC is busy converting.

2.4 CONFIGURATION REGISTER

(Read Address 03h /Write Address 09h): D7 D6 D5 D4 D3 D2 D1 D0 ALERT mask RUN/STOP 0 Remote T_CRIT_A mask

0 Local

T_CRIT_A mask

0 Fault Queue

Power up default is with all bits “0” (zero) D7: ALERT mask: When set to “1” ALERT interrupts are masked. LM89 www.national.com 14

D6: RUN/STOP: When set to “1” SHUTDOWN is enabled. D5: is not defined and defaults to “0”. D4: Remote T_CRIT mask: When set to “1” a diode temperature reading that exceeds T_CRIT setpoint will not activate the T_CRIT_A pin. D3: is not defined and defaults to “0”. D2: Local T_CRIT mask: When set to “1” a Local temperature reading that exceeds T_CRIT setpoint will not activate the T_CRIT_A pin. D1: is not defined and defaults to “0”. D0: Fault Queue: when set to “1” three consecutive remote temperature measurements outside the HIGH, LOW, or T_CRIT setpoints will trigger an “Outside Limit” condition resulting in setting of status bits and associated output pins..

2.5 CONVERSION RATE REGISTER

(Read Address 04h /Write Address 0Ah) Value Conversion Rate 00 62.5 mHz 01 125 mHz 02 250 mHz 03 500 mHz 04 1 Hz 05 2 Hz (Read Address 04h /Write Address 0Ah) Value Conversion Rate 06 4 Hz 07 8 Hz 08 16 Hz 09 32 Hz 10-255 Undefined

2.6 LOCAL and REMOTE HIGH SETPOINT REGISTERS (LHS, RHSHB, and RHSLB)

(Read Address 05h, 07h /Write Address 0Bh, 0Dh): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 For LHS and RHSHB: HIGH setpoint temperature data. Power up default is LHIGH = RHIGH = 70˚C. 1 LSB = 1˚C. Two’s complement format. (Read/Write Address 13h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0.125 00000 For RHSLB: Remote HIGH Setpoint Low Byte temperature data. Power up default is 0˚C. 1 LSB = 0.125˚C. Two’s complement format.

2.7 LOCAL and REMOTE LOW SETPOINT REGISTERS (LLS, RLSHB, and RLSLB)

(Read Address 06h, 08h, /Write Address 0Ch, 0Eh): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 For LLS and RLSHB: HIGH setpoint temperature data. Power up default is LHIGH = RHIGH = 0˚C. 1 LSB = 1˚C. Two’s complement format. (Read/Write Address 14h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0.125 00000 For RLSLB: Remote HIGH Setpoint Low Byte temperature data. Power up default is 0˚C. 1 LSB = 0.125˚C. Two’s complement format.

2.8 REMOTE TEMPERATURE OFFSET REGISTERS (RTOHB and RTOLB)

(Read/Write Address 11h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 LM89 www.national.com15

For RTOHB: Remote Temperature Offset High Byte. Power up default is LHIGH = RHIGH = 0˚C. 1 LSB = 1˚C. Two’s complement format. (Read/Write Address 12h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 0.5 0.25 0.125 00000 The offset value written to these registers will automatically be added to or subtracted from the remote temperature measurement that will be reported in the Remote Temperature registers.

2.9 LOCAL and REMOTE T_CRIT REGISTERS (RCS and LCS)

(Read/Write Address 20h, 19h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value SIGN 64 32 16 8 4 2 1 D7–D0: T_CRIT setpoint temperature data. Power up default is Local T_CRIT = 85˚C and Remote T_CRIT=110˚C. 1 LSB = 1˚C, two’s complement format.

2.10 T_CRIT HYSTERESIS REGISTER (TH)

(Read and Write Address 21h): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 1 6 8421 D7–D0: T_CRIT Hysteresis temperature. Power up default is TH = 10˚C. 1 LSB = 1˚C, maximum value = 31.

2.11 FILTER and ALERT CONFIGURE REGISTER

(Read and Write Address BFh): BIT D7 D6 D5 D4 D3 D2 D1 D0 Value 00000 Filter Level ALERT Configure D7-D3: is not defined defaults to "0". D2-D1: input filter setting as defined the table below: D2 D1 Filter Level 0 0 No Filter 0 1 Level 1 1 0 Level 1 1 1 Level 2 Level 2 sets maximum filtering. D0: when set to "1" comparator mode is enabled.

2.12 MANUFACTURERS ID REGISTER

(Read Address FEh) The default value is 01h.

2.13 DIE REVISION CODE REGISTER

(Read Address FFh) The LM89 version has a default value of 31h or 49 decimal. The LM89-1 version has a default value of 34h or 52 decimal. This register will increment by 1 every time there is a revision to the die by National Semiconductor.

3.0 Applications Hints

The LM89 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 circuit board lands and traces soldered to the LM89’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 surface temperature, the actual temperature of the LM89 die will be at an intermediate temperature between the surface and air temperatures. Again, the primary thermal conduction path is through the leads, so the circuit board temperature will contribute to the die temperature much more strongly than will the air temperature. To measure temperature external to the LM89’s die, use a remote diode. This diode can be located on the die of a target IC, allowing measurement of the IC’s temperature, independent of the LM89’s temperature. The LM89 has been LM89 www.national.com 16

3.0 Applications Hints (Continued)

optimized to measure the remote thermal diode of a 0.13 micron Pentium 4 or a Mobile Pentium 4 Processor-M pro- cessor. A discrete diode can also be used to sense the temperature of external objects or ambient air. Remember that a discrete diode’s temperature will be affected, and often dominated, by the temperature of its leads. Most silicon diodes do not lend themselves well to this application. It is recommended that a 2N3904 transistor base emitter junction be used with the collector tied to the base. An LM89 with a diode-connected 2N3904 approximates the temperature reading of the LM89 with a Pentium 4 micropro- cessor less 1˚C. T 2N3904 =T P4 − 1˚C

3.1 DIODE NON-IDEALITY

3.1.1 Diode Non-Ideality Factor Effect on Accuracy

When a transistor is connected as a diode, the following relationship holds for variables V BE, T and If: where:

• q = 1.6x10−19 Coulombs (the electron charge),
• T = Absolute Temperature in Kelvin
• k = 1.38x10−23joules/K (Boltzmann’s constant),
• η is the non-ideality factor of the process the diode is manufactured on,
• IS = Saturation Current and is process dependent,
• If= Forward Current through the base emitter junction
• VBE = Base Emitter Voltage drop In the active region, the -1 term is negligible and may be eliminated, yielding the following equation In the above equation, η and IS are dependant upon the process that was used in the fabrication of the particular diode. By forcing two currents with a very controlled ratio (N) and measuring the resulting voltage difference, it is possible to eliminate the I S term. Solving for the forward voltage difference yields the relationship: The voltage seen by the LM89 also includes the IFRS voltage drop of the series resistance. The non-ideality factor,η,i s the only other parameter not accounted for and depends on the diode that is used for measurement. Since ∆VBE is proportional to bothη and T, the variations inη cannot 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 4 and Mobile Pentium Processor-M Intel specifies a ±0.1% variation in η from part to part. As an example, assume a temperature sensor has an accuracy specification of ±1˚C at room temperature of 25 ˚C and the process used to manufacture the diode has a non-ideality variation of ±0.1%. The resulting accuracy of the temperature sensor at room temperature will be: The additional inaccuracy in the temperature measurement caused byη, can be eliminated if each temperature sensor is calibrated with the remote diode that it will be paired with. Processor Family η, non-ideality min typ max Pentium III CPUID 67h 1 1.0065 1.0125 Pentium III CPUID 68h/PGA370Socket/Celeron 1.0057 1.008 1.0125 Pentium 4, 423 pin 0.9933 1.0045 1.0368 Pentium 4, 478 pin 0.9933 1.0045 1.0368 0.13 micron, Pentium 4 1.0011 1.0021 1.0030 MMBT3904 1.003 AMD Athlon MP model 6 1.002 1.008 1.016

3.1.2 Compensating for Diode Non-Ideality

In order to compensate for the errors introduced by non- ideality, the temperature sensor is calibrated for a particular processor. National Semiconductor temperature sensors are always calibrated to the typical non-ideality of a given pro- cessor type. The LM89 is calibrated for the non-ideality of a 0.13 micron, Mobile Pentium 4, 1.0021. When a temperature sensor calibrated for a particular processor type is used with a different processor type or a given processor type has a non-ideality that strays from the typical, errors are intro- duced. Temperature errors associated with non-ideality may be re- duced in a specific temperature range of concern through use of the offset registers (11h and 12h). Please send an email to hardware.monitor.team @nsc.com requesting further information on our recommended setting of the offset register for different processor types. LM89 www.national.com17

3.2 PCB LAYOUT for MINIMIZING NOISE

sor and the LM89 can cause temperature conversion errors.

1. A 2.2nF diode bypass capacitor is required to filter high

traces to the 2.2nF capacitor are matched.

1. Ideally, the LM89 should be placed within 10cm of the
2. Diode traces should be surrounded by a GND guard ring
3. Avoid routing diode traces in close proximity to power

supply switching or filtering inductors.

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

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

1. If it is necessary to cross high speed digital traces, the
2. The ideal place to connect the LM89’s GND pin is as
3. Leakage current between D+ and GND should be kept

sible will minimize leakage current. FIGURE 11. Ideal Diode Trace Layout

Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Narrow Small-Outline Package (SOIC), JEDEC Registration Number MS-012 Order Number LM89CIM or LM89CIMX 8-Lead Molded Mini-Small-Outline Package (MSOP), JEDEC Registration Number MO-187 Order Number LM89CIMM or LM89CIMMX LM89 www.national.com19

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