Remote Local System Temperature Monitor ADM1032* ADM1032 dual-cha

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Remote Local System Temperature Monitor ADM1032* ADM1032 dual-cha

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FEATURES On-Chip Remote Temperature Sensing Offset Registers System Calibration 0.125 Resolution/1 Accuracy Remote Channel Resolution/3 Accuracy Local Channel Fast Measurements Second) 2-Wire SMBus Serial Interface Supports SMBus Alert Programmable Over/Under Temperature Limits Programmable Fault Queue Over-Temperature Fail-Safe THERM Output Programmable THERM Limits Programmable THERM Hysteresis Operating Current Standby Current Supply Small 8-Lead Micro_SO Package APPLICATIONS Desktop Computers Notebook Computers Smart Batteries Industrial Controllers Telecomms Equipment Instrumentation Embedded Systems
Remote Local System Temperature Monitor ADM1032*
ADM1032 dual-channel digital thermometer under/over temperature alarm, intended personal computers thermal management systems. higher accuracy offered allows systems designers safely reduce temperature guardbanding increase system performance. device measure temperature microprocessor using diode-connected transistor, which provided on-chip low-cost discrete device such 2N3906. novel measurement technique cancels absolute value transistor's base emitter voltage, that calibration required. second measurement channel measures output on-chip temperature sensor, monitor temperature device environment. ADM1032 communicates over two-wire serial interface compatible with System Management (SMBus) standards. Under over temperature limits programmed into device over serial bus, ALERT output signals when on-chip remote temperature measurement range. This output used interrupt, SMBus alert. THERM output comparator output that allows clock throttling on/off control cooling fan.
FUNCTIONAL BLOCK DIAGRAM
ADDRESS POINTER REGISTER ON-CHIP TEMPERATURE SENSOR CONVERSION RATE REGISTER LOCAL TEMPERATURE VALUE REGISTER LOCAL TEMPERATURE LOW-LIMIT REGISTER
DIGITAL
BUSY
RUN/STANDBY REMOTE TEMPERATURE VALUE REGISTER
LIMIT COMPARATOR
DIGITAL
ANALOG
A-TO-D CONVERTER
LOCAL TEMPERATURE HIGH-LIMIT REGISTER REMOTE TEMPERATURE LOW-LIMIT REGISTER REMOTE TEMPERATURE HIGH-LIMIT REGISTER LOCAL THERM LIMIT REGISTER
REMOTE OFFSET REGISTER
EXTERNAL THERM LIMIT REGISTER CONFIGURATION REGISTER
EXTERNAL DIODE OPEN-CIRCUIT STATUS REGISTER
INTERRUPT MASKING SMBUS INTERFACE
ALERT THERM
ADM1032
SDATA
SCLK
Pentium registered trademark Intel Corporation. *Patents 5,982,221, 6,097,239, 6,133,753, 6,169,442, 5,867,012.
REV.
Information furnished Analog Devices believed accurate reliable. However, responsibility assumed Analog Devices use, infringements patents other rights third parties that result from use. license granted implication otherwise under patent patent rights Analog Devices. Technology Way, P.O. 9106, Norwood, 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 Analog Devices, Inc., 2001
ADM1032-SPECIFICATIONS
TMAX, VMIN VMAX, unless otherwise noted.)
Unit Test Conditions/Comments
Parameter POWER SUPPLY Supply Voltage, Average Operating Supply Current, Undervoltage Lockout Threshold Power-On Reset Threshold TEMPERATURE-TO-DIGITAL CONVERTER Local Sensor Accuracy Resolution Remote Diode Sensor Accuracy Resolution Remote Sensor Source Current Conversion Time
3.30 2.55
2.35
0.0625 Conversions/Sec Rate1 Standby Mode Input, Disables ADC, Rising Edge
100°C, 60°C 100°C, 120°C High Level, Note Level, Note From Stop Conversion Complete (Both Channels) One-Shot Mode with Averaging Switched One-Shot Mode with Averaging (i.e., Conversion Rate Conversions Second)
0.125 35.7 142.8
22.8
OPEN-DRAIN DIGITAL OUTPUTS (THERM, ALERT) Output Voltage, High Level Output Leakage Current, SMBus INTERFACE2 Logic Input High Voltage, SCLK, SDATA Logic Input Voltage, Hysteresis SCLK, SDATA SMBus Output Sink Current ALERT Output Sink Current Logic Input Current, IIH, SMBus Input Capacitance, SCLK, SDATA SMBus Clock Frequency SMBus Timeout SMBus Clock Time, tLOW SMBus Clock High Time, tHIGH SMBus Start Condition Setup Time, tSU:STA SMBus Start Condition Hold Time, tHD:STA SMBus Stop Condition Setup Time, tSU:STO SMBus Data Valid SCLK Rising Edge Time, tSU:DAT SMBus Data Hold Time, tHD:DAT SMBus Free Time, tBUF SCLK Falling Edge SDATA Valid Time, tVD,DAT SCLK, SDATA Rise Time, SCLK, SDATA Fall Time,
IOUT -6.0 VOUT VDD2 SDATA Forced ALERT Forced
Note tLOW between Points tHIGH between Points Time from SDATA SCLK Time from SCLK SDATA Time SDATA SCLK Between Start/Stop Condition Master Clocking
NOTES Table information other conversion rates. Guaranteed Design, production tested. SMBus timeout programmable feature. default enabled. Details enable available SMBus section this data sheet. Specifications subject change without notice.
REV.
ADM1032
ABSOLUTE MAXIMUM RATINGS* THERMAL CHARACTERISTICS
Positive Supply Voltage (VDD) -0.3 +5.5 -0.3 -0.3 +0.6 SCLK, SDATA, ALERT -0.3 +5.5 THERM -0.3 Input Current, SDATA, THERM Input Current, Rating, Pins (Human Body Model) >1000 Maximum Junction Temperature max) 150°C Storage Temperature Range -65°C +150°C Reflow Peak Temp 220°C Lead Temp (Soldering sec) 300°C
*Stresses above those listed under Absolute Maximum Ratings cause permanent damage device. This stress rating only; functional operation device these other conditions above those indicated operational section this specification implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
8-Lead Package 121°C/W 8-Lead Micro_SO Package 142°C/W
CONFIGURATION
SCLK SDATA
ADM1032
VIEW ALERT (Not Scale) THERM
ORDERING GUIDE
Model ADM1032AR ADM1032ARM
Temperature Range 120°C 120°C
Package Description 8-Lead Package 8-Lead Micro_SO Package
Package Option SO-8 RM-8
Branding Information 1032AR
SMBus Addr
tLOW
SCLK
tHD;STA
tHD;STA
SDATA
tHD;DAT
tHIGH tSU;DAT
tSU;STA
tSU;STO
tBUF
Figure Diagram Serial Timing
FUNCTION DESCRIPTIONS
Mnemonic THERM ALERT SDATA SCLK
Description Positive Supply, Positive Connection Remote Temperature Sensor. Negative Connection Remote Temperature Sensor. Open-drain output that used turn on/off throttle clock event overtemperature condition. Requires pull-up VDD. Supply Ground Connection Open-Drain Logic Output Used Interrupt SMBus Alert. Logic Input/Output, SMBus Serial Data. Open-Drain Output. Requires pull-up resistor. Logic Input, SMBus Serial Clock. Requires pull-up resistor.
REV.
ADM1032-Typical Performance Characteristics
TEMPERATURE ERROR
40mV 10mV
TEMPERATURE ERROR
TEMPERATURE ERROR
LEAKAGE RESISTANCE
-0.5 TEMPERATURE
100k
FREQUENCY
100M
Temperature Error Leakage Resistance
Temperature Error Actual Temperature Using 2N3906
Temperature Error Differential Mode Noise Frequency
TEMPERATURE ERROR
SUPPLY CURRENT
250mV
TEMPERATURE ERROR
100mV
FREQUENCY CAPACITANCE
0.01
CONVERSION RATE
Temperature Error Power Supply Noise Frequency
Temperature Error Capacitance between
Operating Supply Current Conversion Rate
STANDBY SUPPLY CURRENT
TEMPERATURE ERROR
100mV
SUPPLY CURRENT
1000 SCLK FREQUENCY 3.3V
50mV 25mV 100k FREQUENCY 100M
SUPPLY VOLTAGE
Temperature Error Common-Mode Noise Frequency
Standby Supply Current Clock Frequency
Standby Supply Current Supply Voltage
REV.
ADM1032
FUNCTIONAL DESCRIPTION
ADM1032 local remote temperature sensor over-temperature alarm. When ADM1032 operating normally, on-board A-to-D converter operates freerunning mode. analog input multiplexer alternately selects either on-chip temperature sensor measure local temperature, remote temperature sensor. These signals digitized results stored Local Remote Temperature Value Registers. measurement results compared with local remote, high, THERM temperature limits, stored nine onchip registers. Out-of-limit comparisons generate flags that stored Status Register, more out-of limit results will cause ALERT output pull low. Exceeding THERM temperature limits cause THERM output assert low. limit registers programmed, device controlled configured, serial System Management (SMBus). contents register also read back SMBus. Control configuration functions consist Switching device between normal operation standby mode. Masking enabling ALERT output. Selecting conversion rate.
MEASUREMENT METHOD
Figure shows input signal conditioning used measure output external temperature sensor. This figure shows external sensor substrate transistor, provided temperature monitoring some microprocessors, could equally well discrete transistor. discrete transistor used, collector will grounded, should linked base. prevent ground noise interfering with measurement, more negative terminal sensor referenced ground, biased above ground internal diode input. sensor operating noisy environment, optionally added noise filter. value typically 2200 should more than 3000 section Layout Considerations more information measure VBE, sensor switched between operating currents resulting waveform passed through low-pass filter remove noise, thence chopperstabilized amplifier that performs functions amplification rectification waveform produce voltage proportional VBE. This voltage measured give temperature output two's complement format. further reduce effects noise, digital filtering performed averaging results measurement cycles. Signal conditioning measurement internal temperature sensor performed similar manner.
TEMPERATURE DATA FORMAT
simple method measuring temperature exploit negative temperature coefficient diode, base-emitter voltage transistor, operated constant current. Unfortunately, this technique requires calibration null effect absolute value VBE, which varies from device device. technique used ADM1032 measure change when device operated different currents. This given
corresponds 0.125°C, measure from 127.875°C. temperature data format shown Tables results local remote temperature measurements stored Local Remote Temperature Value Registers, compared with limits programmed into Local Remote High Limit Registers.
Table Temperature Data Format (Local Temperature Remote Temperature High Byte)
Temperature 10°C 25°C 50°C 75°C 100°C 125°C 127°C
Digital Output 0000 0001 1010 1001 0010 1011 0100 1101 1111
where: Boltzmann's constant (1.38 10-23). charge electron (1.6 10-19 Coulombs). absolute temperature Kelvins. ratio currents. ideality factor thermal diode. ADM1032 trimmed ideality factor 1.008.
IBIAS
REMOTE SENSING TRANSISTOR BIAS DIODE LOW-PASS FILTER 65kHz
VOUT+ VOUT-
*CAPACITOR OPTIONAL. SHOULD ONLY USED NOISY ENVIRONMENTS. 2.2nF TYPICAL, MAX.
Figure Input Signal Conditioning
REV.
ADM1032
Table Extended Temperature Resolution (Remote Temperature Byte) Status Register
Extended Resolution 0.000°C 0.125°C 0.250°C 0.375°C 0.500°C 0.625°C 0.750°C 0.875°C
ADM1032 REGISTERS
Remote Temperature Byte 0000 0000 0000 0000 0000 0000 0000 0000
Status Register indicates that busy converting when high. Bits flags that indicate results limit comparisons. when remote sensor open circuit. local and/or remote temperature measurement above corresponding high temperature limit, below equal corresponding temperature limit, more these flags will set. These five flags (Bits NOR'd together, that them high, ALERT interrupt latch will ALERT output will low. Reading Status Register will clear five flag bits, provided error conditions that caused flags have gone away. While limit comparator tripped value register containing out-of-limit measurement, sensor open circuit, corresponding flag cannot reset. flag only reset corresponding value register contains in-limit measurement sensor good. ALERT interrupt latch reset reading Status Register, will reset when ALERT output been serviced master reading device address, provided error condition gone away Status Register flag bits have been reset. When Flags set, THERM output goes indicate that temperature measurements outside programmed limits. THERM output does need reset, unlike ALERT output. Once measurements within limits, corresponding Status register bits reset THERM output goes high.
Table Status Register Assignments
ADM1032 contains registers that used store results remote local temperature measurements, high temperature limits, configure control device. description these registers follows, further details given Tables VII.
Address Pointer Register
Address Pointer Register itself does have, require, address, register which first data byte every Write operation written automatically. This data byte address pointer that sets other registers second byte Write operation, subsequent read operation. power-on default value Address Pointer Register 00h, read operation performed immediately after poweron without first writing Address Pointer, value local temperature will returned, since register address 00h.
Value Registers
Name BUSY LHIGH* LLOW* RHIGH* RLOW* OPEN* RTHRM LTHRM
Function When Converting When Local High-Temp Limit Tripped When Local Low-Temp Limit Tripped When Remote High-Temp Limit Tripped When Remote Low-Temp Limit Tripped When Remote Sensor Open-Circuit When Remote Therm Limit Tripped When Local Therm Limit Tripped
ADM1032 three registers store results Local Remote temperature measurements. These registers written only read over SMBus.
Offset Register
Series resistance lines processor packages clock noise introduce offset errors into remote temperature measurement. achieve specified accuracy this channel these offsets must removed. offset value stored 11-bit, two's complement value registers (high byte) (low byte, left justified). value offset negative register positive register value added measured value remote temperature. offset register powers with default value 0°C, will have effect nothing written them.
Table III. Sample Offset Register Codes
*These flags stay high until status register read they reset POR.
Configuration Register
bits Configuration Register used. which power-on default, device operating mode with converting. device standby mode does convert. SMBus does, however, remain active Standby Mode values read from written SMBus. ALERT THERM O/Ps also active Standby Mode. configuration register used mask alert output. which power-on default, output enabled. output disabled.
Offset Value -4°C -1°C -0.125°C +0.125°C +1°C +4°C
1100 1111 1111 0000 0000 0001 0100
0000 0000 0000 0000 0000 0000 0000
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ADM1032
Table Configuration Register Assignments
Name MASK1 RUN/STOP
Function ALERT Enabled ALERT Masked Standby Reserved
Power-On Default
Consecutive ALERT Register This value written this register determines many out-oflimit measurements must occur before ALERT generated. default value that out-of-limit measurement generates ALERT. value that chosen purpose this register allow user perform some filtering output. This particularly useful faster conversion rates where averaging takes place.
Table VII.
Conversion Rate Register
lowest four bits this register used program conversion rate dividing internal oscillator clock 128, 256, 512, 1024 give conversion times from 15.5 (code 0Ah) seconds (code 00h). This register written read back over SMBus. higher four bits this register unused must zero. slower conversion times greatly reduces device power consumption, shown Table
Table Conversion Rate Register Codes
Register Value yxxx 000x yxxx 001x yxxx 011x yxxx 111x
Number "Out-of-Limit" Measurements Required
NOTES Don't care bit. SMBus timeout bit. Default SMBus section more information.
Data
Conversion/sec 0.0625 0.125 0.25 Reserved
Average Supply Current 0.17 0.20 0.21 0.24 0.29 0.40 0.61 0.73 1.23
SERIAL INTERFACE
Control ADM1032 carried serial bus. ADM1032 connected this slave device, under control master device. There programmable SMBus timeout. When this enabled SMBus will timeout after typically activity. However, this feature enabled default. enable Consecutive Alert Register (Addr 22h). ADM1032 supports Packet Error Checking (PEC) optional. triggered supplying extra clock byte. byte calculated using CRC-8. Frame Check Sequence (FCS) conforms CRC-8 polynomial: C(x) Consult SMBus specification more information (www.smbus.org).
ADDRESSING DEVICE
Limit Registers
ADM1032 nine Limit Registers store local remote, high, low, THERM temperature limits. These registers written read back over SMBus. high limit registers perform comparison while limit registers perform comparison. example, high limit register programmed with 80°C, then measuring 81oC will result alarm condition. Limit Register programmed with 0°C, measuring lower will result Alarm condition. Exceeding either Local Remote THERM limit asserts THERM low. default hysteresis value 10°C provided, which applies both channels. This hysteresis reprogrammed value after power (Reg 0x21h).
One-Shot Register
general, every SMBus device 7-bit device address (except some devices that have extended, 10-bit addresses). When master device sends device address over bus, slave device with that address will respond. ADM1032 available with device address, which (1001 100). serial protocol operates follows: master initiates data transfer establishing START condition, defined high-to-low transition serial data line SDATA, while serial clock line SCLK remains high. This indicates that address/data stream will follow. slave peripherals connected serial respond START condition, shift next eight bits, consisting 7-bit address (MSB first) plus bit, which determines direction data transfer, i.e., whether data will written read from slave device. peripheral whose address corresponds transmitted address responds pulling data line during period before ninth clock pulse, known Acknowledge Bit. other devices remain idle while selected device waits data read from written
One-Shot Register used initiate single conversion comparison cycle when ADM1032 standby mode, after which device returns standby. This data register such, write operation that causes one-shot conversion. data written this address irrelevant stored. conversion time single shot when conversion rate conversions second less. conversions second conversion time 15.3 This because averaging disabled faster conversion rates conversions second). REV.
ADM1032
Table VIII. List ADM1032 Registers
Read Address (Hex) Applicable Applicable
Write Address (Hex) Applicable Applicable Applicable Applicable Applicable Applicable Applicable
Name Address Pointer Local Temperature Value External Temperature Value High Byte Status Configuration Conversion Rate Local Temperature High Limit Local Temperature Limit External Temperature High Limit High Byte External Temperature Limit High Byte One-Shot External Temperature Value Byte External Temperature Offset High Byte External Temperature Offset Byte External Temperature High Limit Byte External Temperature Limit Byte External THERM Limit Local THERM Limit THERM Hysteresis Consecutive ALERT Manufacturer Revision Code
Power-On Default Undefined 0000 0000 (00h) 0000 0000 (00h) Undefined 0000 0000 (00h) 0000 1000 (08h) 0101 0101 (55h) (85°C) 0000 0000 (00h) (0°C) 0101 0101 (55h) (85°C) 0000 0000 (00h) (0°C) 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0101 0101 (55h) (85°C) 0101 0101 (55h) (85°C) 0000 1010 (0Ah) (10°C) 0000 0001 (01h) 0100 0001 (41h) Undefined
Writing address causes ADM1032 perform single measurement. data register such does matter what data written
master will write slave device. master will read from slave device. Data sent over serial sequences nine clock pulses, eight bits data followed Acknowledge from slave device. Transitions data line must occur during period clock signal remain stable during high period, low-to-high transition when clock high interpreted STOP signal. number data bytes that transmitted over serial single Read Write operation limited only what master slave devices handle. When data bytes have been read written, stop conditions established. Write mode, master will pull data line high during tenth clock pulse assert STOP condition. Read mode, master device will override acknowledge pulling data line high during period before ninth clock pulse. This known Acknowledge. master will then take data line during period before tenth clock pulse, then high during tenth clock pulse assert STOP condition. number bytes data transferred over serial operation, possible read write operation because type operation determined beginning cannot subsequently changed without starting operation. case ADM1032, write operations contain either bytes, while read operations contain byte, perform following functions:
write data device data registers read data from Address Pointer Register must that correct data register addressed, then data written into that register read from first byte write operation always contains valid address that stored Address Pointer Register. data written device, write operation contains second data byte that written register selected address pointer register. This illustrated Figure device address sent over followed This followed data bytes. first data byte address internal data register written which stored Address Pointer Register. second data byte data written internal data register. When reading data from register there possibilities: ADM1032's Address Pointer Register value unknown desired value, first necessary correct value before data read from desired data register. This done performing write ADM1032 before, only data byte containing register read address sent, data written register. This shown Figure read operation then performed consisting serial address, followed data byte read from data register. This shown Figure Address Pointer Register known already desired address, data read from corresponding data register without first writing Address Pointer Register Figure omitted.
REV.
ADM1032
Although possible read data byte from data register without first writing Address Pointer Register, Address Pointer Register already correct value, possible write data register without writing Address Pointer Register, because first data byte write always written Address Pointer Register.
SCLK
Don't forget that some ADM1032 registers have different addresses read write operations. write address register must written Address Pointer data written that register, possible read data from that address. read address register must written Address Pointer before data read from that register.
SDATA START MASTER
ACK. ADM1032
ACK. ADM1032
FRAME SERIAL ADDRESS BYTE SCLK (CONTINUED)
FRAME ADDRESS POINTER REGISTER BYTE
SDATA (CONTINUED)
ACK. ADM1032 STOP MASTER
FRAME DATA BYTE
Figure Writing Register Address Address Pointer Register, then Writing Data Selected Register
SCLK
SDATA START MASTER
ACK. ADM1032
ACK. ADM1032 STOP MASTER
FRAME SERIAL ADDRESS BYTE
FRAME ADDRESS POINTER REGISTER BYTE
Figure Writing Address Pointer Register Only
SCLK
SDATA START MASTER
ACK. ADM1032
ACK. ADM1032 STOP MASTER
FRAME SERIAL ADDRESS BYTE
FRAME DATA BYTE FROM ADM1032
Figure Reading Data from Previously Selected Register
ALERT OUTPUT
ALERT output goes whenever out-of-limit measurement detected, remote temperature sensor open-circuit. open drain requires pull-up VDD. Several ALERT outputs wire-ORed together, that common line will more ALERT outputs goes low. ALERT output used interrupt signal processor, used SMBALERT. Slave devices SMBus normally signal master that they want talk, SMBALERT function allows them
more ALERT outputs connected common SMBALERT line connected master. When SMBALERT line pulled devices, following procedure occurs illustrated Figure
MASTER RECEIVES SMBALERT START ALERT RESPONSE ADDRESS MASTER SENDS READ COMMAND DEVICE ADDRESS STOP
DEVICE SENDS ADDRESS
Figure SMBALERT
REV.
ADM1032
SMBALERT pulled low. Master initiates read operation sends Alert Response Address (ARA 0001 100). This general call address that must used specific device address. device whose ALERT output responds Alert Response Address master reads device address. device address seven bits, added. address device known interrogated usual way. more than device's ALERT output low, with lowest device address, will have priority, accordance with normal SMBus arbitration. Once ADM1032 responded Alert Response Address, will reset ALERT output, provided that error condition that caused ALERT longer exists. SMBALERT line remains low, master will send again, until devices whose ALERT outputs were have responded.
LOW-POWER STANDBY MODE
THERM Hysteresis Value provided prevent cooling cycling off. power-on default value 10°C this reprogrammed value after power-up. This hysteresis value applies both local remote channels Using these limits this allows user gain maximum performance from system only slowing down, should critical temperature. THERM signal open drain requires pull-up VDD. THERM signal must always pulled same power supply ADM1032, unlike SMBus signals (SDATA, SCLK, ALERT) which pulled different power rail, usually that SMBus controller.
THERM TEMPERATURE LOCAL THERM LIMIT -HYSTERESIS LOCAL THERM LIMIT
ADM1032 into low-power standby mode setting Configuration Register. When low, ADM1032 operates normally. When high, inhibited, conversion progress terminated without writing result corresponding value register. SMBus still enabled. Power consumption standby mode reduced less than there SMBus activity, there clock data signals bus. When device standby mode, still possible initiate one-shot conversion both channels writing One-Shot Register (address 0Fh), after which device will return standby. also possible write values limit register while standby. values stored temperature value registers outside limits, ALERT generated even though ADM1032 still standby.
ADM1032 INTERRUPT SYSTEM
Figure Operation THERM Output
Table THERM HYSTERESIS Sample Values
THERM HYSTERESIS 10°C
SENSOR FAULT DETECTION
Binary Representation 0000 0001 1010
ADM1032 interrupt outputs, ALERT THERM. These have different functions. ALERT responds violations software-programmed temperature limits maskable. THERM intended "fail-safe" interrupt output that cannot masked. temperature goes equal below lower temperature limit, ALERT will asserted indicate out-of-limit condition. temperature within programmed high temperature limits, interrupt will generated. temperature exceeds high temperature limit, ALERT will asserted indicate over temperature condition. local remote THERM limit, programmed into device temperature limit above which over temperature THERM will asserted low. This temperature limit should equal greater than high temperature limit programmed. behavior high limit THERM limit follows: either temperature measured exceeds high temperature limit, ALERT output will assert low. local remote temperature continues increase either exceeds THERM limit, THERM output asserts low. This used throttle clock switch fan.
input ADM1032 fault detector that detects external sensor diode open-circuit. This simple voltage comparator that trips voltage exceeds (typical). output this comparator checked when conversion initiated, sets Status Register fault detected. remote sensor voltage falls below normal measuring range, example diode being short-circuited, will output -128 (1000 0000). Since normal operating temperature range device only extends down 0°C, this output code should never seen normal operation, interpreted fault condition. Since will outside power-on default temperature limit (0°C) limit that would normally programmed, short-circuit sensor will cause SMBus alert. this respect ADM1032 differs from improves upon, competitive devices that output zero external sensor goes short-circuit. These devices misinterpret genuine measurement fault condition. When lines shorted together, ALERT will always generated. This because remote value register reports temperature value -128°C. Since ADM1032 performs less-than equal-to comparison with limit, ALERT generated even when limit minimum -128°C. REV.
-10-
ADM1032
APPLICATIONS INFORMATION FACTORS AFFECTING ACCURACY Remote Sensing Diode
ADM1032 designed work with substrate transistors built into processors' CPUs with discrete transistors. Substrate transistors will generally types with collector connected substrate. Discrete types either transistor connected diode (base shorted collector). transistor used, collector base connected emitter transistor used, collector base connected emitter Substrate transistors found number CPUs. reduce error variations these substrate discrete transistors, number factors should taken into consideration: ideality factor, transistor. ideality factor measure deviation thermal diode from ideal behavior. ADM1032 trimmed value 1.008. following equation used calculate error introduced temperature when using transistor whose does equal 1.008. Consult processor datasheet values.
temperature change. case remote sensor this should problem, will either substrate transistor processor, small package device such SOT-23 placed close proximity on-chip sensor, however, will often remote from processor, will only monitoring general ambient temperature around package. thermal time constant SO-8 package still about seconds, ambient temperature quickly changed degrees, would take about minutes time constants) junction temperature ADM1032 settle within degree this. practice, ADM1032 package will electrical, hence thermal, contact with printed circuit board, also forced airflow. accurately temperature board and/or forced airflow reflect temperature measured will also affect accuracy. Self-heating power dissipated ADM1032 remote sensor, causes chip temperature device remote sensor rise above ambient. However, current forced through remote sensor small that self-heating negligible. case ADM1032, worst-case condition occurs when device converting conversions second while sinking maximum current ALERT THERM output. this case, total power dissipation device about thermal resistance, SO-8 package about 121°C/W. practice, package will have electrical hence thermal connection printed circuit board, temperature rise self-heating will negligible.
LAYOUT CONSIDERATIONS
natural
1.008 (273.15 Kelvin 1.008
This value written offset register automatically added subtracted from temperature measurement. Some manufacturers specify high current levels substrate transistors. high current level ADM1032, IHIGH, level current, ILOW, ADM1032 current levels match levels manufacturers, then become necessary remove offset. CPU's datasheet will advise whether this offset needs removed calculate This offset programmed offset register. important note that accounting more offsets needed, then algebraic these offsets must programmed Offset Register. discrete transistor being used with ADM1032 best accuracy will obtained choosing devices according following criteria: Base-emitter voltage greater than 0.25 highest operating temperature. Base-emitter voltage less than 0.95 lowest operating temperature. Base resistance less than Small variation (say 150) that indicates tight control characteristics. Transistors such 2N3904, 2N3906, equivalents SOT-23 packages suitable devices use.
THERMAL INERTIA SELF-HEATING
Digital boards electrically noisy environments, ADM1032 measuring very small voltages from remote sensor, care must taken minimize noise induced sensor inputs. following precautions should taken: Place ADM1032 close possible remote sensing diode. Provided that worst noise sources, i.e., clock generators, data/address buses, CRTs, avoided, this distance inches. Route tracks close together, parallel, with grounded guard tracks each side. Provide ground plane under tracks possible. wide tracks minimize inductance reduce noise pickup. track minimum width spacing recommended.
10MIL 10MIL 10MIL 10MIL 10MIL 10MIL 10MIL
Accuracy depends temperature remote-sensing diode and/or internal temperature sensor being same temperature that being measured, number factors affect this. Ideally, sensor should good thermal contact with part system being measured, example processor. not, thermal inertia caused mass sensor will cause response sensor REV.
Figure Arrangement Signal Tracks
minimize number copper/solder joints, which cause thermocouple effects. Where copper/solder joints used, make sure that they both path same temperature. -11-
ADM1032
Thermocouple effects should major problem corresponds about thermocouple voltages about V/°C temperature difference. Unless there thermocouples with temperature differential between them, thermocouple voltages should much less than Place bypass capacitor close pin. very noisy environments place 2200 input filter capacitors across close ADM1032. distance remote sensor more than inches, twisted pair cable recommended. This will work about feet. really long distances feet) shielded twisted pair such Belden #8451 microphone cable. Connect twisted pair shield close ADM1032. Leave remote shield unconnected avoid ground loops.
3.6V
Because measurement technique uses switched current sources, excessive cable and/or filter capacitance affect measurement. When using long cables, filter capacitor reduced removed. Cable resistance also introduce errors. series resistance introduces about error.
APPLICATION CIRCUIT
C01906-.8-10/01(0) PRINTED U.S.A.
Figure shows typical application circuit ADM1032, using discrete sensor transistor connected shielded, twisted pair cable. pull-ups SCLK, SDATA, ALERT required only they already provided elsewhere system. SCLK, SDATA pins ADM1032 interfaced directly SMBus controller such Intel chipset.
ADM1032
SCLK SHIELD 2N3906 THERMAL DIODE SDATA ALERT THERM
SMBUS CONTROLLER
CONTROL CIRCUIT ENABLE
Figure Typical Application Circuit
OUTLINE DIMENSIONS
Dimensions shown inches (mm).
8-Lead (R-8)
0.1968 (5.00) 0.1890 (4.80)
8-Lead Micro_SO (RM-8)
0.122 (3.10) 0.114 (2.90)
0.1574 (4.00) 0.1497 (3.80)
0.2440 (6.20) 0.2284 (5.80)
0.122 (3.10) 0.114 (2.90)
0.199 (5.05) 0.187 (4.75)
0.0500 (1.27) 0.0098 (0.25) 0.0040 (0.10) SEATING PLANE 0.0688 (1.75) 0.0532 (1.35) 0.0192 (0.49) 0.0138 (0.35) 0.0098 (0.25) 0.0075 (0.19)
0.0196 (0.50) 0.0099 (0.25)
0.0256 (0.65) 0.120 (3.05) 0.112 (2.84) 0.006 (0.15) 0.002 (0.05) 0.015 (0.38) SEATING 0.009 (0.22) PLANE 0.043 (1.09) 0.037 (0.94) 0.009 (0.23) 0.003 (0.08) 0.120 (3.05) 0.112 (2.84)
0.0500 (1.27) 0.0160 (0.41)
0.028 (0.71) 0.016 (0.41)
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Remote Local System Temperature Monitor ADM1032* ADM1032 dual-cha

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