LM99 Accurate, High Temperature, Remote Diode Temperature Sensor with

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LM99 Accurate, High Temperature, Remote Diode Temperature Sensor with Two-Wire Interface
LM99 Accurate, High Temperature, Remote Diode Temperature Sensor with Two-Wire Interface
LM99 11-bit remote diode temperature sensor with 2-wire System Management (SMBus) serial interface. LM99 accurately measures: temperature temperature remote diode-connected transistor such 2N3904 thermal diode commonly found Graphics Processor Units (GPU), Computer Processor Units (CPU other ASICs. LM99 remote diode temperature sensor shifts temperature from remote sensor down 16°C operates that shifted temperature: TACTUAL DIODE JUNCTION TLM99 16°C local temperature reading requires offset. LM99 Offset Register which provides means precise matching various thermal diodes. Contact hardware.monitor@nsc.com latest details. LM99 LM99-1 have same functions different SMBus slave addresses. This allows each same same time. Activation ALERT output occurs when temperature goes outside preprogrammed window HIGH temperature limit registers exceeds T_CRIT temperature limit. Activation T_CRIT_A occurs when temperature exceeds T_CRIT programmed limit. On-board local temperature sensing plus sign remote diode temperature data format, 0.125 resolution T_CRIT_A output useful system shutdown ALERT output supports SMBus protocol SMBus compatible interface, supports TIMEOUT 8-pin MSOP package
Specifications
Supply Voltage Supply Current
(typ) 25°C 125°C
Local Temp Accuracy (includes quantization error)
3.0°C (max)
Remote Diode Temp Accuracy (includes quantization
error) 30°C 50°C, 120°C 140°C 85°C, 25°C 140°C
1.0°C (max) 3.0°C (max)
Applications
Graphics Processor Thermal Management Computer Processor Thermal Management Electronic Test Equipment Office Electronics
Features
Accurately senses temperature remote diodes Offset register allows variety thermal diodes
Simplified Block Diagram
20053801
NVIDIA registered trademark NVIDIA Corporation. GeForceis trademark NVIDIA Corporation. Intel Pentium registered trademarks Intel Corporation.
2003 National Semiconductor Corporation
DS200538
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LM99
Connection Diagram
MSOP-8
20053802
VIEW
Ordering Information
Part Number LM99CIMM LM99-1CIMM LM99CIMMX LM99-1CIMMX Package Marking T17C T20C T17C T20C Package Number MUA08A (MSOP-8) MUA08A (MSOP-8) MUA08A (MSOP-8) MUA08A (MSOP-8) Transport Media 1000 Units Tape Reel 1000 Units Tape Reel 3500 Units Tape Reel 3500 Units Tape Reel
Descriptions
Label Function Typical Connection Voltage from should bypassed with capacitor parallel with ground. capacitor should placed close possible power supply pin. bulk capacitance approximately needs vicinity LM99 VDD. Diode Anode. Connected collector base remote discrete diode-connected transistor. Connect capacitor between pins Diode Cathode. Connects emitter remote diode-connected transistor. Connect capacitor between pins Pull-Up Resistor, Controller Interrupt Power Supply Shutdown Control Ground Pull-Up Resistor, Controller Interrupt Alert Line From Controller, Pull-Up Resistor From Controller, Pull-Up Resistor
Positive Supply Voltage Input
Diode Current Source
Diode Return Current Sink T_CRIT Alarm Output, Open-Drain, Active-Low Power Supply Ground Interrupt Output, Open-Drain, Active-Low SMBus Bi-Directional Data Line, Open-Drain Output SMBus Input
T_CRIT_A ALERT SMBData SMBCLK
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LM99
Typical Application
20053803
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LM99
Absolute Maximum Ratings
Supply Voltage Voltage SMBData, SMBCLK, ALERT, T_CRIT_A Voltage Other Pins Input Current Input Current Other Pins (Note Package Input Current (Note SMBData, ALERT, T_CRIT_A Output Sink Current Storage Temperature Soldering Information, Lead Temperature
(Note
MSOP-8 Packages (Note Vapor Phase seconds) Infrared seconds) Susceptibility (Note Human Body Model Machine Model 2000 215°C 220°C
-0.3 -0.5 -0.3 (VDD
Operating Ratings
(Notes Operating Temperature Range Electrical Characteristics Temperature Range LM99 Supply Voltage Range (VDD) +125°C TMIN TMAX +85°C +3.0 +3.6
-65°C +150°C
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply +3.0 +3.6 Vdc. Boldface limits apply TMIN TMAX; other limits +25°C, unless otherwise noted. Parameter Temperature Error Using Local Diode Temperature Error Using Remote Diode Connected Transistor Remote Diode Junction Temperature) TLM99 16°C Remote Diode Measurement Resolution Local Diode Measurement Resolution Conversion Time Temperatures Fastest Setting Quiescent Current (Note (Note SMBus Inactive, conversion rate Shutdown Source Voltage Diode Source Current (VD+ VD-) 0.65 high level level ALERT T_CRIT_A Output Saturation Voltage Power-On-Reset (POR) Threshold Local Remote HIGH Default Temperature settings Local Remote Default Temperature settings Local T_CRIT Default Temperature Setting Remote T_CRIT Default Temperature Setting IOUT Measure input, falling edge (Note 16°C true Remote Temperature. (Note 16°C true Remote Temperature. (Note (Note 16°C 126°C true Remote T_CRIT Setting +110 Conditions +25°C +125°C, (Note +30°C +50°C +120°C +140°C +0°C +85°C +25°C +140°C 0.125 31.25 34.4 Typical (Note Limits (Note Units (Limit) (max) (max) (max) Bits Bits (max) (max) (max) (min) (max) (min) (max) (max) (min)
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LM99
Logic Electrical Characteristics
DIGITAL CHARACTERISTICS Unless otherwise noted, these specifications apply +3.0 Vdc. Boldface limits apply TMIN TMAX; other limits +25°C, unless otherwise noted. Symbol Parameter Conditions Typical (Note SMBData, SMBCLK INPUTS VIN(1) VIN(0) VIN(HYST) IIN(1) IIN(0) Logical Input Voltage Logical "0"Input Voltage SMBData SMBCLK Digital Input Hysteresis Logical Input Current Logical Input Current Input Capacitance High Level Output Current SMBus Level Output Voltage 0.005 -0.005 (min) (max) Limits (Note Units (Limit)
(max) (max) (max) (max)
DIGITAL OUTPUTS
SMBus Digital Switching Characteristics
Unless otherwise noted, these specifications apply +3.0 +3.6 Vdc, (load capacitance) output lines Boldface limits apply TMIN TMAX; other limits +25°C, unless otherwise noted. switching characteristics LM99 fully meet exceed published specifications SMBus version 2.0. following parameters timing relationships between SMBCLK SMBData signals related LM99. They adhere necessarily SMBus specifications. Symbol fSMB tLOW tHIGH tR,SMB tF,SMB tTIMEOUT tSU;DAT tHD;DAT tHD;STA Parameter SMBus Clock Frequency SMBus Clock Time SMBus Clock High Time SMBus Rise Time SMBus Fall Time Output Fall Time SMBData SMBCLK Time Reset Serial Interface (Note Data Setup Time SMBCLK High Data Stable after SMBCLK Start Condition SMBData SMBCLK (Start condition hold before first clock falling edge) Stop Condition SMBCLK High SMBData (Stop Condition Setup) SMBus Repeated Start-Condition Setup Time, SMBCLK High SMBData SMBus Free Time Between Stop Start Conditions from VIN(0)max VIN(0)max from VIN(1)min VIN(1)min (Note (Note (Note Conditions Typical (Note Limits (Note Units (Limit) (max) (min) (min) (max) (min) (max) (max) (max) (min) (max) (min) (min) (max) (min)
tSU;STO tSU;STA tBUF
(min) (min) (min)
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LM99
SMBus Communication
20053840
Note Absolute Maximum Ratings indicate limits beyond which damage device occur. electrical specifications apply when operating device beyond rated operating conditions. Note When input voltage (VI) exceeds power supplies VDD), current that should limited Parasitic components protection circuitry shown figure below LM99's pins. nominal breakdown voltage Care should taken forward bias parasitic diode, present pins: Doing more than corrupt temperature measurement.
Name T_CRIT_A ALERT SMBData SMBCLK
CLAMP
Note: indicates that diode exists.
20053813
FIGURE Protection Input Structure
Note other recommendations methods soldering surface mount devices. Note Human body model, discharged through resistor. Machine model, discharged directly into each pin. Note Thermal resistance junction-to-ambient when attached printed circuit board with foil: MSOP-8 210°C/W Note Typicals 25°C represent most likely parametric norm. Note Limits guaranteed National's AOQL (Average Outgoing Quality Level). Note Local temperature accuracy does include effects self-heating. rise temperature self-heating product internal power dissipation LM99 thermal resistance. (Note thermal resistance used self-heating calculation. Note Quiescent current will increase substantially with SMBus. Note This specification provided only indicate often temperature data updated. LM99 read time without regard conversion state (and will yield last conversion result). Note Default values power Note output rise time measured from (VIN(0)max 0.15 (VIN(1)min 0.15 Note output fall time measured from (VIN(1)min 0.15 (VIN(1)min 0.15 Note Holding SMBData and/or SMBCLK lines time interval greater than tTIMEOUT will reset LM99's SMBus state machine, therefore setting SMBData SMBCLK pins high impedance state.
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LM99
Functional Description
LM99 temperature sensor incorporates delta based temperature sensor using Local Remote diode 10-bit plus sign (Delta-Sigma Analog-toDigital Converter). LM99 compatible with serial SMBus version two-wire interface. Digital comparators compare measured Local Temperature (LT) Local High (LHS), Local (LLS) Local T_CRIT (LCS) userprogrammable temperature limit registers. measured Remote Temperature (RT) digitally compared Remote High (RHS), Remote (RLS) Remote T_CRIT (RCS) user-programmable temperature limit registers. Activation ALERT output indicates that comparison greater than limit preset T_CRIT HIGH limit register less than limit preset limit register. T_CRIT_A output responds true comparator with built hysteresis. hysteresis value placed Hysteresis register (TH). Activation T_CRIT_A occurs when temperature above T_CRIT setpoint. T_CRIT_A remains activated until temperature goes below setpoint calculated T_CRIT hysteresis register impacts both remote temperature local temperature readings. LM99 placed power consumption (Shutdown) mode setting RUN/STOP found Configuration register. Shutdown mode, LM99's SMBus interface remains while circuitry required turned off. Local temperature reading setpoint data registers 8-bits wide. format 11-bit remote temperature data 16-bit left justified word. 8-bit registers, high bytes, provided each setpoint well temperature reading. offset registers (RTOLB RTOHB) used compensate non-ideality error, discussed further Section DIODE NON-IDEALITY. remote temperature reading reported adjusted subtracting from, adding actual temperature reading value placed offset register. CONVERSION SEQUENCE LM99 takes approximately 31.25 convert Local Temperature (LT), Remote Temperature (RT), update registers. Only during conversion process busy (D7) Status register (02h) high. These conversions addressed round-robin sequence. conversion rate modified Conversion Rate Register (04h). When conversion rate modified delay inserted between conversions; however, actual conversion time remains 31.25 Different conversion rates will cause LM99 draw different amounts supply current shown Figure
20053839
FIGURE Conversion Rate Effect Power Supply Current ALERT OUTPUT LM99's ALERT active-low open-drain output that triggered temperature conversion that outside limits defined temperature setpoint registers. Reset ALERT output dependent upon selected method use. LM99's ALERT versatile will accommodate three different methods best serve system designer: temperature comparator, temperature-based interrupt flag, part SMBus ALERT system. three methods further described below. ALERT interrupt methods different only user interacts with LM99. Each temperature reading associated with T_CRIT setpoint register (LCS, RCS), HIGH setpoint register (LHS RHS) setpoint register (LLS RLS). every temperature reading, digital comparison determines whether that reading above HIGH T_CRIT setpoint below setpoint. corresponding STATUS REGISTER set. ALERT mask high, STATUS REGISTER, with exception Busy (D7) OPEN (D2), will cause ALERT output pulled low. temperature conversion that limits defined temperature setpoint registers will trigger ALERT. Additionally, ALERT mask Configuration register must cleared trigger ALERT modes. 1.2.1 ALERT Output Temperature Comparator When LM99 implemented system which serviced interrupt routine, ALERT output could used temperature comparator. Under this method use, once condition that triggered ALERT longer present, ALERT de-asserted (Figure example, ALERT output activated comparison LHS, when this condition longer true ALERT will return HIGH. This mode allows operation without software intervention, once registers configured during set-up. order ALERT used temperature comparator, (the ALERT configure bit) FILTER ALERT CONFIGURE REGISTER (xBF) must high. This power default default state.
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LM99
Functional Description
(Continued)
20053828
20053831
FIGURE ALERT Output Interrupt Temperature Response Diagram 1.2.3 ALERT Output SMBus ALERT When ALERT output connected more ALERT outputs other SMBus compatible devices master, SMBus alert line created. Under this implementation, LM99's ALERT should operated using (Alert Response Address) protocol. SMBus protocol, defined SMBus specification 2.0, procedure designed assist master resolving which part generated interrupt service that interrupt while impeding system operation little possible. SMBus alert line connected open-drain ports devices thereby AND'ing them together. method which with command SMBus master identify which part pulling SMBus alert line prevent from pulling again same triggering condition. When command received devices bus, devices pulling SMBus alert line LOW, first, send their address master second, release SMBus alert line after recognizing successful transmission their address. SMBus specification state that response (Alert Response Address) "after acknowledging slave address device must disengage SMBALERT pulldown". Furthermore, host still sees SMBALERT when message transfer complete, knows read again". This SMBus "disengaging SMBALERT" requirement prevents locking SMBus alert line. Competitive parts address this "disengaging SMBALERT" requirement differently than LM99 all. SMBus systems that implement protocol suggested LM99 will fully compatible with competitive parts. LM99 fulfills "disengaging SMBALERT" setting ALERT mask (bit Configuration register, address 09h) after successfully sending address response releasing ALERT output pin. Once ALERT mask activated, ALERT output will disabled until enabled software. order enable ALERT master must read STATUS REGISTER, address 02h, during interrupt service routine then reset ALERT mask Configuration register interrupt service routine. following sequence describes response protocol.
FIGURE ALERT Comparator Temperature Response Diagram 1.2.2 ALERT Output Interrupt LM99's ALERT output implemented simple interrupt signal when used trigger interrupt service routine. such systems undesirable interrupt flag repeatedly trigger during before interrupt service routine been completed. Under this method operation, during read STATUS REGISTER LM99 will ALERT mask Configuration register) STATUS REGISTER set, with exception Busy (D7) OPEN (D2). This prevents further ALERT triggering until master reset ALERT mask bit, interrupt service routine. STATUS REGISTER bits cleared only upon read command from master (see Figure will re-asserted next conversion triggering condition(s) persist(s). order ALERT used dedicated interrupt signal, (the ALERT configure bit) FILTER ALERT CONFIGURE REGISTER (xBF) must low. This power-on default state. following sequence describes response system that uses ALERT output interrupt flag: Master Senses ALERT Master reads LM99 STATUS REGISTER determine what caused ALERT LM99 clears STATUS REGISTER, resets ALERT HIGH sets ALERT mask Configuration register). Master attends conditions that caused ALERT triggered. started, setpoint limits adjusted, etc. Master resets ALERT mask Configuration register).
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LM99
Functional Description
Master Senses SMBus alert line
(Continued)
reset only after Status Register read temperature conversion(s) is/are below T_CRIT setpoint, shown Figure
Master sends START followed Alert Response Address (ARA) with Read Command. Alerting Device(s) send ACK. Alerting Device(s) send their Address. While transmitting their address, alerting devices sense whether their address been transmitted correctly. (The LM99 will reset ALERT output ALERT mask once complete address been transmitted successfully.) Master/slave NoACK Master sends STOP Master attends conditions that caused ALERT triggered. STATUS REGISTER read started, setpoint limits adjusted, etc. Master resets ALERT mask Configuration register).
20053806
FIGURE T_CRIT_A Temperature Response Diagram POWER RESET DEFAULT STATES LM99 always powers these known default states. LM99 remains these states until after first conversion. Command Register Local Temperature Remote Diode Temperature until first conversion. Status Register 00h. Configuration register 00h; ALERT enabled, Remote T_CRIT alarm enabled Local T_CRIT alarm enabled 85°C Local T_CRIT temperature setpoint 110°C Remote T_CRIT temperature setpoint (126°C Remote diode junction temperature) 70°C Local Remote HIGH temperature setpoints Local Remote temperature setpoints Filter Alert Configure Register 00h; filter disabled, ALERT output SMBus ALERT Conversion Rate Register conversion rate conv./sec.
ARA, 1100, general call address. device should ever assigned this address. (the ALERT configure bit) FILTER ALERT CONFIGURE REGISTER (xBF) must order LM99 respond command. ALERT output disabled setting ALERT mask bit, Configuration register. power default have ALERT mask ALERT configure low.
20053829
FIGURE ALERT Output SMBus ALERT Temperature Response Diagram T_CRIT_A OUTPUT T_CRIT LIMIT T_CRIT_A activated when temperature reading greater than limit preset critical temperature setpoint register (T_CRIT), shown Figure Status Register read determine which event caused alarm. Status Register high indicate which temperature reading exceeded T_CRIT setpoint temperature caused alarm, Section 2.3. Local remote temperature diodes sampled sequence converter. T_CRIT_A output Status Register flags updated after every Local Remote temperature conversion. T_CRIT_A follows state comparison, reset when temperature falls below setpoint RCS-TH. Status Register flags
SMBus INTERFACE LM99 operates slave SMBus, SMBCLK line input SMBData line bidirectional. LM99 never drives SMBCLK line does support clock stretching. According SMBus specifications, LM99 7-bit slave address. bits through internally programmed changed software hardware. LM99 LM99-1 have following slave addresses: Version LM99 LM99-1
TEMPERATURE DATA FORMAT Temperature data only read from Local Remote Temperature registers; setpoint registers (T_CRIT, LOW, HIGH) read/write.
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LM99
Functional Description
(Continued)
0.125°C. data format left justified 16-bit word available 8-bit registers:
Remote temperature data represented 11-bit, two's complement word with (Least Significant Bit) equal Actual LM99 Remote Temperature Conversion Actual Remote Diode Temperature,°C
Output 11-bit two's complement word. 0.125
LM99 Remote Diode Temperature Register, +104 +109 +110 +114 +119 +124
Binary Results LM99 Remote Temperature Register 0110 1000 0000 0000 0110 1101 0000 0000 0110 1110 0000 0000 0111 0010 0010 0000 0111 0111 0000 0000 0111 1100 0000 0000
Remote Temperature Register 6800h 6D00h 7100h 7200h 7700h 7200h
Actual Remote T_Crit Setpoint Actual Remote Diode T_Crit Setpoint,°C Factory-Programmed Remote T_CRIT High Setpoint, +110 Binary Remote T_CRIT High Setpoint Value 0110 1110 Remote T_CRIT High Setpoint Value
Local Temperature data represented 8-bit, two's complement byte with (Least Significant Bit) equal 1°C: Local Temperature +125°C +25°C +1°C -1°C -25°C -55°C Digital Output Binary 0111 1101 0001 1001 0000 0001 0000 0000 1111 1111 1110 0111 1100 1001
OPEN-DRAIN OUTPUTS SMBData, ALERT T_CRIT_A outputs opendrain outputs have internal pull-ups. "high" level will observed these pins until pull-up current provided some external source, typically pull-up resistor. Choice resistor value depends many system factors but, general, pull-up resistor should large possible. This will minimize internal temperature reading errors internal heating LM99. maximum resistance pull-up provide 2.1V high level, based LM99 specification High Level Output Current with supply voltage 3.0V, (5%) 88.7 (1%).
DIODE FAULT DETECTION LM99 equipped with operational circuitry designed detect fault conditions concerning remote diode. event that detected shorted floating, Remote Temperature High Byte (RTHB) register loaded with +127°C, Remote Temperature Byte (RTLB) register loaded with OPEN (D2) status register set. result, Remote T_CRIT setpoint register (RCS) value less than +127°C ALERT T_Crit output pins will pulled low, Alert Mask T_Crit Mask disabled. Remote HIGH Setpoint High Byte Register (RHSHB) value less than +127°C then ALERT will pulled low, Alert Mask disabled. OPEN itself will trigger ALERT. event that shorted ground Remote Temperature High Byte (RTHB) register loaded with -128°C (1000 0000) OPEN (D2) status register will set. Since operating LM99 -128°C beyond it's operational limits, this temperature reading represents this shorted fault condition. value Remote Setpoint High Byte Register (RLSHB) more than -128°C Alert Mask disabled, ALERT will pulled low. Remote diode temperature sensors that have been previously released competitive with LM99 output code external diode short-circuited. This change improvement that allows reading truly interpreted genuine reading fault condition.
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LM99
Functional Description
COMMUNICATING WITH LM99
(Continued)
data registers LM99 selected Command Register. power-up Command Register "00", location Read Local Temperature Register. Command Register latches last location Each data register LM99 falls into four types user accessibility: Read only Write only Read/Write same address
Read/Write different address Write LM99 will always include address byte command byte. write register requires data byte. Reading LM99 take place either ways: location latched Command Register correct (most time expected that Command
Register will point Read Temperature Registers because that will data most frequently read from LM99), then read simply consist address byte, followed retrieving data byte. Command Register needs set, then address byte, command byte, repeat start, another address byte will accomplish read. data byte most significant first. read, LM99 accept either Acknowledge Acknowledge from Master Acknowledge typically used signal slave that Master read last byte). takes LM99 31.25 measure temperature remote diode internal diode. When retrieving bits from previous remote diode temperature measurement, master must insure that bits from same temperature conversion. This achieved using one-shot mode setting conversion rate monitoring busy such that conversion occurs between reading last temperature conversion.
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LM99
Functional Description
1.9.1 SMBus Timing Diagrams LM99 Timing Diagram
(Continued)
20053810
Serial Write internal Command Register followed Data Byte
20053811
Serial Write Internal Command Register
20053812
Serial Read from Register with Internal Command Register preset desired value. FIGURE SMBus Timing Diagrams 1.10 SERIAL INTERFACE RESET event that SMBus Master RESET while LM99 transmitting SMBData line, LM99 must returned known state communication protocol. This done ways: When SMBData LOW, LM99 SMBus state machine resets SMBus idle state either SMBData SMBCLK held more than (tTIMEOUT). Note that according SMBus specification devices timeout when either SMBCLK SMBData lines held 25-35 Therefore, insure timeout devices SMBCLK SMBData lines must held least When SMBData HIGH, have master initiate SMBus start. LM99 will respond properly SMBus start condition point during communication. After start LM99 will expect SMBus Address address byte.
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LM99
Functional Description
1.11 DIGITAL FILTER
(Continued)
filter. filter accessed FILTER ALERT CONFIGURE REGISTER BFh. filter according table shown. Level sets maximum filtering. Figure depict filter output response step input impulse input. Figure depicts digital filter Pentium processor system. Note that curves, with filter without, have been purposely offset that both responses clearly seen. Inserting filter does induce offset shown.
Filter Filter Level Level Level
order suppress erroneous remote temperature readings noise, LM99 incorporates user-configured digital
20053825
20053826
Step Response
Impulse Response
FIGURE Filter Output Response Step Input
20053827
FIGURE Digital Filter Response Pentium processor System. filter curves were purposely offset better show noise performance.
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LM99
Functional Description
1.12 FAULT QUEUE
(Continued)
order suppress erroneous ALERT T_CRIT triggering LM99 incorporates Fault Queue. Fault Queue acts insure remote temperature measurement genuinely beyond HIGH, T_CRIT setpoint triggering until three consecutive limit measurements have been made, Figure fault queue defaults upon power-on activated setting Configuration register (09h) "1".
1.13 ONE-SHOT REGISTER One-Shot register used initiate single conversion comparison cycle when device standby mode, after which device returns standby. This data register write operation that causes one-shot conversion. data written this address irrelevant stored. zero will always read from this register.
20053830
FIGURE Fault Queue Temperature Response Diagram
LM99 Registers
COMMAND REGISTER Selects which registers will read from written Data this register should transmitted during Command Byte SMBus write communication.
Command Select P0-P7: Command Select Command Select Address Read Address P7:P0 Write Address P7:P0 Power Default State
D7:D0 binary
0000 0000 0000 0000 0000 0000 0000 0000 0000 1000 0100 0110 0000 0000 0100 0110 0000 0000
D7:D0
decimal conv./sec)
Register Name RTHB RHSHB RLSHB Shot
Register Function
Local Temperature Remote Temperature High Byte Status Register Configuration Conversion Rate Local HIGH Setpoint Local Setpoint Remote HIGH Setpoint High Byte Remote Setpoint High Byte Writing this register will initiate shot conversion
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LM99
LM99 Registers
Read Address P7:P0 B0h-BEh
(Continued) Power Default State Register Name RTLB RTOHB RTOLB RHSLB RLSLB RDTF RMID Register Function
Command Select Address Write Address P7:P0 B0h-BEh
D7:D0 binary
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0110 1110 0101 0101 0000 1010 0000 0000 0000 0001 LM99 0011 0001 LM99-1 0011 0100
D7:D0
decimal
Remote Temperature Byte Remote Temperature Offset High Byte Remote Temperature Offset Byte Remote HIGH Setpoint Byte Remote Setpoint Byte Remote T_CRIT Setpoint Local T_CRIT Setpoint T_CRIT Hysteresis Manufacturers Test Registers Remote Diode Temperature Filter Read Manufacturer's Read Stepping Revision Code
LOCAL REMOTE TEMPERATURE REGISTERS (LT, RTHB, RTLB) (Read Only Address 00h, 01h): Value SIGN
RTHB D7-D0: Temperature Data. 1°C. Two's complement format. (Read Only Address 10h): Value 0.25 0.125
RTLB D7-D5: Temperature Data. 0.125°C. Two's complement format. maximum value available from Local Temperature register 127; minimum value available from Local Temperature register -128. maximum value available from Remote Temperature register 127.875; minimum value available from Remote Temperature registers -128.875. Note that remote diode junction temperature actually 16°C higher than Remote Temperature Register value. STATUS REGISTER (SR) (Read Only Address 02h): Busy LHIGH LLOW RHIGH RLOW OPEN RCRIT LCRIT
Power default with bits (zero). LCRIT: When indicates Local Critical Temperature alarm. RCRIT: When indicates Remote Diode Critical Temperature alarm. OPEN: When indicates Remote Diode disconnect. RLOW: When indicates Remote Diode Temperature alarm RHIGH: When indicates Remote Diode HIGH Temperature alarm. LLOW: When indicates Local Temperature alarm. LHIGH: When indicates Local HIGH Temperature alarm. Busy: When busy converting.
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LM99
LM99 Registers
(Continued)
CONFIGURATION REGISTER (Read Address Write Address 09h): ALERT mask RUN/STOP Remote T_CRIT_A mask Local T_CRIT_A mask Fault Queue
Power default with bits (zero) ALERT mask: When ALERT interrupts masked. RUN/STOP: When SHUTDOWN enabled. defined defaults "0". Remote T_CRIT_A mask: When diode temperature reading that exceeds T_CRIT_A setpoint will activate T_CRIT_A pin. defined defaults "0". Local T_CRIT_A mask: When Local temperature reading that exceeds T_CRIT_A setpoint will activate T_CRIT_A pin. defined defaults "0". Fault Queue: when three consecutive remote temperature measurements outside HIGH, LOW, T_CRIT setpoints will trigger "Outside Limit" condition resulting setting status bits associated output pins. CONVERSION RATE REGISTER (Read Address Write Address 0Ah) Value Conversion Rate 62.5 (Read Address Write Address 0Ah) Value 10-255 Conversion Rate Undefined
LOCAL REMOTE HIGH SETPOINT REGISTERS (LHS, RHSHB, RHSLB) (Read Address 05h, Write Address 0Bh, 0Dh): Value SIGN
RHSHB: HIGH setpoint temperature data. Power-on default LHIGH RHIGH 70°C. 1°C. Two's complement format. (Read Write Address 13h): Value 0.25 0.125
RHSLB: Remote HIGH Setpoint Byte temperature data. Power-on default 0°C. 0.125°C. Two's complement format. LOCAL REMOTE SETPOINT REGISTERS (LLS, RLSHB, RLSLB) (Read Address 06h, 08h, Write Address 0Ch, 0Eh): Value SIGN
RLSHB: HIGH setpoint temperature data. Power-on default LHIGH RHIGH 0°C. 1°C. Two's complement format. (Read Write Address 14h): Value 0.25 0.125
RLSLB: Remote HIGH Setpoint Byte temperature data. Power-on default 0°C. 0.125°C. Two's complement format.
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LM99
LM99 Registers
(Continued)
REMOTE TEMPERATURE OFFSET REGISTERS (RTOHB RTOLB) (Read Write Address 11h): Value SIGN
RTOHB: Remote Temperature Offset High Byte. Power-on default LHIGH RHIGH 0°C. 1°C. Two's complement format. (Read Write Address 12h): Value 0.25 0.125
RTOLB: Remote Temperature Offset High Byte. Power-on default 0°C. 0.125°C. Two's complement format. offset value written these registers will automatically added subtracted from remote temperature measurement that will reported Remote Temperature registers. LOCAL REMOTE T_CRIT REGISTERS (RCS LCS) (Read Write Address 20h, 19h): Value SIGN
D7-D0: T_CRIT setpoint temperature data. Local power-on default T_CRIT 85°C. Remote power-on default T_CRIT 110°C (+126°C actual remote diode temperature). 1°C, two's complement format. 2.10 T_CRIT HYSTERESIS REGISTER (TH) (Read Write Address 21h): Value
D7-D0: T_CRIT Hysteresis temperature. Power-on default 10°C. 1°C, maximum value 2.11 FILTER ALERT CONFIGURE REGISTER (Read Write Address BFh): Value Filter Level ALERT Configure
D7-D3: defined defaults "0". D2-D1: input filter setting defined table below: Level sets maximum filtering. when comparator mode enabled. 2.12 MANUFACTURERS REGISTER (Read Address FEh) Default value 01h. 2.13 REVISION CODE REGISTER (Read Address FFh) LM99 version default value decimal. LM99-1 version default value decimal. This register will increment every time there revision National Semiconductor. Filter Level Filter Level Level Level
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LM99
Application Hints
LM99 applied easily same other integrated-circuit temperature sensors, remote diode sensing capability allows used ways well. soldered printed circuit board, because path best thermal conductivity between pins, temperature will effectively that printed circuit board lands traces soldered LM99's pins. This presumes that ambient temperature almost same surface temperature printed circuit board; temperature much higher lower than surface temperature, actual temperature LM99 will intermediate temperature between surface temperatures. Again, primary thermal conduction path through leads, circuit board temperature will contribute temperature much more strongly than will temperature. measure temperature external LM99's die, remote diode. This diode located target allowing measurement IC's temperature, independent LM99's temperature. LM99 been optimized measure NVIDIA GeForceTMFX family thermal diode. Remember that discrete diode's temperature will affected, often dominated, temperature leads. DIODE NON-IDEALITY 3.1.1 Diode Non-Ideality Factor Effect Accuracy When transistor connected diode, following relationship holds variables VBE,
above equation, dependant upon process that used fabrication particular diode. forcing currents with very controlled ratio measuring resulting voltage difference, possible eliminate term. Solving forward voltage difference yields relationship:
voltage seen LM99 also includes IFRS voltage drop series resistance. non-ideality factor, only other parameter accounted depends diode that used measurement. Since proportional both variations cannot distinguished from variations temperature. Since nonideality factor controlled temperature sensor, will directly inaccuracy sensor. example, assume temperature sensor accuracy specification room temperature process used manufacture diode non-ideality variation 0.1%. resulting accuracy temperature sensor room temperature will TACC 0.1% additional inaccuracy temperature measurement caused eliminated each temperature sensor calibrated with remote diode that will paired with. 3.1.2 Compensating Diode Non-Ideality order compensate errors introduced nonideality, temperature sensor calibrated particular processor. National Semiconductor temperature sensors always calibrated typical non-ideality given processor type. LM99 calibrated non-ideality NVIDIA GeForceFX family thermal diode. When temperature sensor calibrated particular processor type used with different processor type given processor type non-ideality that strays from typical, errors introduced. Temperature errors associated with non-ideality reduced specific temperature range concern through offset registers (11h 12h). Offset Register table below. Please send email hardware.monitor.team@nsc.com requesting further information recommended setting offset register different processor types.
where:
1.6x10-19 Coulombs (the electron charge), Absolute Temperature Kelvin 1.38x10-23 joules/K (Boltzmann's constant), non-ideality factor process diode manufactured Saturation Current process dependent, Forward Current through base-emitter junction
Base-Emitter Voltage drop active region, term negligible eliminated, yielding following equation
Offset Register Settings Specific Devices Processor Family NVIDIA GeForceFX Graphics Processor Intel Pentium Processor Intel Pentium Processor default +2.625 +2.375 Offset Register Settings Register default 0000 0010 0000 0010 Register default 1010 0000 0110 0000
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LM99
Application Hints
(Continued)
LAYOUT MINIMIZING NOISE
guard should between lines. event that noise does couple diode lines would ideal coupled common mode. That equally lines. Avoid routing diode traces close proximity power supply switching filtering inductors. Avoid running diode traces close parallel high speed digital lines. Diode traces should kept least apart from high speed digital traces. necessary cross high speed digital traces, diode traces high speed digital traces should cross degree angle. ideal place connect LM99's close possible Processors associated with sense diode. Leakage current between should kept minimum. nano-ampere leakage cause much error diode temperature reading. Keeping printed circuit board clean possible will minimize leakage current. Noise coupling into digital lines greater than mVp-p (typical hysteresis) undershoot less than below GND, prevent successful SMBus communication with LM99. SMBus acknowledge most common symptom, causing unnecessary traffic bus. Although SMBus maximum frequency communication rather (100 max), care still needs taken ensure proper termination within system with multiple parts long printed circuit board traces. lowpass filter with corner frequency about included LM99's SMBCLK input. Additional resistance added series with SMBData SMBCLK lines further help filter noise ringing. Minimize noise coupling keeping digital traces switching power supply areas well ensuring that digital lines containing high speed data communications cross right angles SMBData SMBCLK lines.
20053817
FIGURE Ideal Diode Trace Layout noisy environment, such processor mother board, layout considerations very critical. Noise induced traces running between remote temperature diode sensor LM99 cause temperature conversion errors. Keep mind that signal level LM99 trying measure microvolts. following guidelines should followed: Place power supply bypass capacitor close possible recommended capacitor close possible LM99's pins. Make sure traces capacitor matched. Ideally, LM99 should placed within Processor diode pins with traces being straight, short identical possible. Trace resistance cause much error. This error compensated using Remote Temperature Offset Registers, since value placed these registers will automatically subtracted from added remote temperature reading. Diode traces should surrounded guard ring either side, above below possible. This
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LM99 Accurate, High Temperature, Remote Diode Temperature Sensor with Two-Wire Interface
Physical Dimensions
inches (millimeters) unless otherwise noted
8-Lead Molded Mini-Small-Outline Package (MSOP), JEDEC Registration Number MO-187 Order Number LM99CIMM LM99CIMMX Package Number MUA08A
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National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.

LM99 Accurate, High Temperature, Remote Diode Temperature Sensor with

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