LM82 Remote Diode and Local Digital Temperature Sensor with Two-Wire Interface (Rev. D)
Document overview
- Manufacturer or author: Texas Instruments, Incorporated [SNIS113,D]
- PDF pages: 25
Technical content
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 LM82RemoteDiodeandLocalDigitalTemperatureSensorwithTwo-WireInterface Check forSamples: LM82 1FEATURES DESCRIPTION The LM82 isa digitaltemperaturesensor witha 2 2• AccuratelySenses Die Temperature ofRemote wireserialinterfacethatsenses thevoltageand thusICs,or Diode Junctions the temperatureof a remote diode using a Delta-• On-board LocalTemperature Sensing Sigma analog-to-digitalconverterwitha digitalover-
- SMBus and I2C Compatible Interface,Supports temperaturedetector.The LM82 accuratelysenses itsown temperatureas wellas the temperatureofSMBus 1.1TIMEOUT externaldevices,such as Pentium IIProcessorsor• Two InterruptOutputs:INT and T_CRIT_A diode connected2N3904s. The temperatureof any• RegisterReadback Capability ASIC can be detectedusingthe LM82 as longas a
- 7 bitPlus Sign Temperature Data Format,1°C dedicateddiode(semiconductorjunction)isavailable on the die.Using the SMBus interfacea host canResolution accesstheLM82's registersatany time.Activationof• 2 Address SelectPins Allow Connection of9 a T_CRIT_A outputoccurswhen any temperatureisLM82s on a SingleBus greater than a programmable comparator limit, T_CRIT. Activationofan INT outputoccurswhen anyAPPLICATIONS temperature is greater than its corresponding programmablecomparatorHIGH limit.• System Thermal Management
- Computers The hostcan program as wellas readback thestate of the T_CRIT registerand the 2 T_HIGH registers.• ElectronicTestEquipment Three statelogicinputsallowtwo pins(ADD0, ADD1)• OfficeElectronics to selectup to 9 SMBus address locationsforthe
- HVAC LM82. The sensorpowers up withdefaultthresholds of127°C forT_CRIT and allT_HIGHs. The LM82 is KEY SPECIFICATIONS pin forpin and registercompatiblewiththe LM84, Maxim MAX1617 and AnalogDevicesADM1021.• Supply Voltage:3.0to3.6V
- Supply Current:0.8mA (max)
- LocalTemp Accuracy (includesquantization error): – 0 to+85 ±3.0°C (max)
- Remote Diode Temp Accuracy (includes quantizationerror): – +25°C to+100°C ±3°C (max) – 0°C to+125°C ±4°C (max) Pleasebe aware thatan importantnoticeconcerningavailability,standardwarranty,and use incriticalapplicationsof Texas Instrumentssemiconductorproductsand disclaimerstheretoappearsattheend ofthisdatasheet. 2Alltrademarksarethepropertyoftheirrespectiveowners. PRODUCTION DATA informationiscurrentas ofpublicationdate. Copyright© 2000–2013,Texas InstrumentsIncorporatedProductsconform to specificationsper the terms of the Texas Instrumentsstandardwarranty.Productionprocessingdoes not necessarilyincludetestingofallparameters.
T_CRIT Limit Register HIGH Limit Registers Configuration and Status Registers Mfr ID Register Two-Wire Serial Interface ADD0 ADD1 SMBData SMBCLK 8-bit '6 A/D Converter T_CRIT_A INT 3.0V-3.6V LM82 SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com SimplifiedBlock Diagram Connection Diagram Figure1. SSOP-TOP VIEW See DBQ Package
2 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 TypicalApplication PIN DESCRIPTIONS Label Pin # Function TypicalConnection floating,unconnected Leftfloating.PC boardtracesmay be routedthroughthepadsNC 1,5 forthesepins.No restrictionsapplied. VCC 2 PositiveSupplyVoltageInput DC Voltagefrom3.0V to3.6V DiodeCurrentSource To DiodeAnode.Connectedtoremotediscretediodejunction D+ 3 ortothediodejunctionon a remoteIC whose dietemperature isbeingsensed.When notused theyshouldbe leftfloating. D − 4 DiodeReturnCurrentSink To DiodeCathode.Must floatwhen notused. User-SetSMBus (I2C) Address Ground (Low,“0”),VCC (High,“1”)oropen (“TRI-LEVEL”)ADD0 –ADD1 10,6 Inputs GND 7,8 Power SupplyGround Ground Manufacturingtestpins. Leftfloating.PC boardtracesmay be routedthroughthepads forthesepins,althoughthecomponents thatdrivethesetracesNC 9,13,15 shouldsharethesame supplyas theLM82 so thatthe AbsoluteMaximum Rating,VoltageatAny Pin,isnotviolated. INT 11 InterruptOutput,open-drain PullUp Resistor,ControllerInterruptorAlertLine SMBus (I2C) SerialBi- From and toController,Pull-UpResistor SMBData 12 DirectionalData Line,open- drainoutput SMBCLK 14 SMBus (I2C) ClockInput From Controller,Pull-UpResistor CriticalTemperatureAlarm, PullUp Resistor,ControllerInterruptLineorSystem ShutdownT_CRIT_A 16 open-drainoutput Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com These deviceshave limitedbuilt-inESD protection.The leadsshouldbe shortedtogetherorthedeviceplacedinconductivefoam duringstorageorhandlingtopreventelectrostaticdamage totheMOS gates. AbsoluteMaximum Ratings (1) SupplyVoltage −0.3V to6.0V VoltageatSMBData, SMBCLK, T_CRIT_A & INT pins −0.5Vto6V VoltageatOtherPins −0.3V to(VCC + 0.3V) D − InputCurrent ±1 mA InputCurrentatAllOtherPins(2) 5 mA Package InputCurrent(2) 20 mA SMBData, T_CRIT_A, INT OutputSinkCurrent 10 mA StorageTemperature −65°C to+150°C SolderingInformation,Lead Temperature Infrared(15seconds) 220°C ESD Susceptibility(4) Human Body Model 2000 V Machine Model 250 V (1) AbsoluteMaximum Ratingsindicatelimitsbeyond whichdamage tothedevicemay occur.DC and AC electricalspecificationsdo not applywhen operatingthedevicebeyond itsratedoperatingconditions. (2) When theinputvoltage(VI)atany pinexceedsthepower supplies(VI< GND orVI> VCC ),thecurrentatthatpinshouldbe limitedto5 mA. The 20 mA maximum package inputcurrentratinglimitsthenumber ofpinsthatcan safelyexceed thepower supplieswithan input currentof5 mA tofour.Parasiticcomponents and orESD protectioncircuitryareshown inthefigurebelowfortheLM82 's pins.The nominalbreakdown voltageofthezenerD3 is6.5V.Care shouldbe takennottoforwardbiastheparasiticdiode,D1, presenton pins: D+, D −,ADD1 and ADD0. Doingso by more than50 mV may corrupta temperatureorvoltagemeasurement. (3) See thesectiontitled“SurfaceMount”foundina currentTexas InstrumentsLinearData Book forothermethods ofsolderingsurface mount devices. (4) Human body model,100 pF dischargedthrougha 1.5kΩ resistor.Machine model,200 pF dischargeddirectlyintoeach pin. OperatingRatings SpecifiedTemperatureRange TMIN toTMAX LM82 −40°C to+125°C SupplyVoltageRange (VCC ) +3.0V to+3.6V Temperature-to-DigitalConverterCharacteristics Unlessotherwisenoted,thesespecificationsapplyforVCC =+3.0Vdc to3.6Vdc.BoldfacelimitsapplyforTA = TJ = TMIN to TMAX ;allotherlimitsTA= TJ=+25°C, unlessotherwisenoted. Typical(1) Limits(2) UnitsParameter Conditions (Limit) TemperatureErrorusingLocalDiode (3) TA = 0 °C to+85°C, ±1 ±3 °C (max) VCC =+3.3V TA = −40 °C to+125°C, ±4 °C (max) VCC =+3.3V TemperatureErrorusingRemote Diode (3) TA = +60 °C to+100°C, ±3 °C (max)VCC =+3.3V TA = 0 °C to+100°C, ±3 °C (max) VCC =+3.3V TA = 0 °C to+125°C, ±4 °C (max) VCC =+3.3V Resolution 8 Bits 1 °C (1) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (2) LimitsareensuredtoAOQL (AverageOutgoingQualityLevel). (3) The TemperatureErrorwillvarylessthan±1.0°C fora variationinVCC of3V to3.6Vfromthenominalof3.3V.
4 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 Temperature-to-DigitalConverterCharacteristics(continued) Unlessotherwisenoted,thesespecificationsapplyforVCC =+3.0Vdc to3.6Vdc.BoldfacelimitsapplyforTA = TJ = TMIN to TMAX ;allotherlimitsTA= TJ=+25°C, unlessotherwisenoted. Typical(1) Limits(2) UnitsParameter Conditions (Limit) ConversionTime ofAllTemperatures (4) 460 600 ms (max) QuiescentCurrent(5) SMBus (I2C) Inactive 0.500 0.80 mA (max) D − SourceVoltage 0.7 V DiodeSourceCurrent (D+ − D −)=+0.65V;highlevel 125 μA (max) 60 μA (min) Low level 15 μA (max) 5 μA (min) T_CRIT_A and INT OutputSaturation IOUT = 3.0mA 0.4 V (max)Voltage Power-On ResetThreshold On VCC input,fallingedge 2.3 V (max)
1.8 V (min)
Localand Remote T_CRIT and HIGH See (6) +127 °C DefaultTemperaturesettings (4) Thisspecificationisprovidedonlytoindicatehow oftentemperaturedataisupdated.The LM82 can be readatany timewithoutregard toconversionstate(andwillyieldlastconversionresult). (5) Quiescentcurrentwillnotincreasesubstantiallywithan activeSMBus. (6) Defaultvaluessetatpower up. Logic ElectricalCharacteristics- DIGITAL DC CHARACTERISTICS Unlessotherwisenoted,thesespecificationsapplyforVCC =+3.0to3.6Vdc.BoldfacelimitsapplyforTA = TJ = TMIN to TMAX ;allotherlimitsTA= TJ=+25°C, unlessotherwisenoted. Typical(1) Limits(2) UnitsSymbol Parameter Conditions (Limit) SMBData, SMBCLK VIN(1) Logical“1”InputVoltage 2.1 V (min) VIN(0) Logical“0”InputVoltage 0.8 V (max) VIN(HYST) SMBData and SMBCLK DigitalInput 300 mV Hysteresis IIN(1) Logical“1”InputCurrent VIN = VCC 0.005 1.5 μA (max) IIN(0) Logical“0”InputCurrent VIN = 0 V −0.005 1.5 μA (max) ADD0, ADD1 VIN(1) Logical“1”InputVoltage VCC 1.5 V (min) VIN(0) Logical“0”InputVoltage GND 0.6 V (max) IIN(1) Logical“1”InputCurrent VIN = VCC 2 μA (max) IIN(0) Logical“0”InputCurrent VIN = 0 V -2 μA (max) ALL DIGITAL INPUTS C IN InputCapacitance 20 pF ALL DIGITAL OUTPUTS IOH HighLevelOutputCurrent VOH = VCC 100 μA (max) VOL SMBus Low LevelOutputVoltage IOL = 3 mA 0.4 V (max) IOL = 6 mA 0.6 (1) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (2) LimitsareensuredtoAOQL (AverageOutgoingQualityLevel). Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com Logic ElectricalCharacteristics- SMBus DIGITAL SWITCHING CHARACTERISTICS Unlessotherwisenoted,thesespecificationsapplyforVCC =+3.0Vdc to+3.6Vdc,C L (loadcapacitance)on outputlines= 80 pF.BoldfacelimitsapplyforTA = TJ = TMIN toTMAX ;allotherlimitsTA = TJ = +25°C, unlessotherwisenoted. The switchingcharacteristicsoftheLM82 fullymeet orexceed thepublishedspecificationsoftheSMBus orI2C bus.The followingparametersarethetimingrelationshipsbetween SMBCLK and SMBData signalsrelatedtotheLM82. They arenot theI2C orSMBus bus specifications. Typical(1) Limits(2) UnitsSymbol Parameter Conditions (Limit) fSMB SMBus ClockFrequency 100 kHz (max) 10 kHz (min) tLOW SMBus ClockLow Time 10 % to10 % 1.3 μs (min) 25 ms (max) tLOW MEXT CumulativeClockLow ExtendTime 10 ms (max) tHIGH SMBus ClockHighTime 90 % to90% 0.6 μs (min) tR,SMB SMBus RiseTime 10% to90% 1 μs (max) tF,SMB SMBus FallTime 90% to10% 0.3 ns (max) tOF OutputFallTime C L = 400 pF, 250 ns (max) IO = 3 mA tTIMEOUT SMBData and SMBCLK Time Low forResetof 25 ms (min) SerialInterface(3) 40 ms (max) t1 SMBCLK (Clock)Period 10 μs (min) t2,tSU;DAT Data InSetupTime toSMBCLK High 100 ns (min) t3,tHD;DAT Data Out StableafterSMBCLK Low 300 ns (min) TBD ns (max) t4,tHD;STA SMBData Low SetupTime toSMBCLK Low 100 ns (min) t5,tSU;STO SMBData HighDelayTime afterSMBCLK High 100 ns (min) (StopConditionSetup) t6,tSU;STA SMBus Start-ConditionSetupTime 0.6 μs (min) tBUF SMBus FreeTime 1.3 μs (min) (1) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (2) LimitsareensuredtoAOQL (AverageOutgoingQualityLevel). (3) HoldingtheSMBData and/orSMBCLK linesLow fora timeintervalgreaterthantTIMEOUT willcause theLM82 toresetSMBData and SMBCLK totheIDLE stateofan SMBus communication(SMBCLK and SMBData setHigh). Figure2. SMBus Communication
6 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 Figure3. SMBus TIMEOUT Pin Name D1 D2 D3 D4 Pin Name D1 D2 D3 D4 NC (pins1 & 5) T_CRIT_A & INT x VCC x(1) SMBData x x D+ x x x NC (pins9 & 15) x x x D − x x x x SMBCLK x x ADD0, ADD1 x x x NC (pin13) x x (1) Note:An x indicatesthatthediodeexists. Figure4. ESD ProtectionInputStructure Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com Figure5. Temperature-to-DigitalTransferFunction(Non-linearscaleforclarity) Figure6. PrintedCircuitBoard Used forThermal ResistanceSpecifications
8 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM82 temperaturesensorincorporatesa band-gaptypetemperaturesensorusinga LocalorRemote diode and an 8-bitADC (Delta-SigmaAnalog-to-DigitalConverter).The LM82 iscompatiblewiththeserialSMBus and I2C two wireinterfaces.Digitalcomparatorscompare Local(LT)and Remote (RT)temperaturereadingstouser- programmable setpoints(LHS, RHS, and TCS). Activationof the INT outputindicatesthata comparisonis greaterthan the limitpresetina HIGH register.The T_CRIT setpoint(TCS) interactswithallthe temperature readings.ActivationoftheT_CRIT_A outputindicatesthatany or allofthetemperaturereadingshave exceed theT_CRIT setpoint. CONVERSION SEQUENCE The LM82 convertsitsown temperatureas wellas a remotediodetemperatureinthefollowingsequence: 1. LocalTemperature(LT) 2. Remote Diode(RT) Thisroundrobinsequence takesapproximately480 ms tocomplete. INT OUTPUT and T_HIGH LIMITS Each temperaturereading(LT,and RT) isassociatedwitha T_HIGH setpointregister(LHS,RHS). At theend of a temperaturereadinga digitalcomparisondetermineswhetherthatreadinghas exceeded itsHIGH setpoint.If thetemperaturereadingisgreaterthantheHIGH setpoint,a bitissetinone oftheStatusRegisters,toindicate whichtemperaturereading,and theINT outputisactivated. Localand remote temperaturediodesare sampled insequence by theA/D converter.The INT outputand the StatusRegisterflagsare updatedatthecompletionofa conversion,which occursapproximately60 ms aftera temperaturediodeissampled.INT isdeactivatedwhen theStatusRegister,containingthesetbit,isreadand a temperaturereadingislessthanor equaltoit'scorrespondingHIGH setpoint,as shown inFigure7.Figure8 shows a simplifiedlogicdiagramfortheINT outputand relatedcircuitry. *Note:StatusRegisterBitsareresetby a readofStatusRegisterwhere bitislocated. Figure7. INT Temperature Response Diagram Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com Figure8. INT outputrelatedcircuitrylogicdiagram The INT outputcan be disabledby settingthe INT mask bit,D7, of the configurationregister.INT can be programmed tobe activehighorlow by thestateoftheINT inversionbit,D1, intheconfigurationregister.A “0” wouldprogramINT tobe activelow.INT isan open-drainoutput. T_CRIT_A OUTPUT and T_CRIT LIMIT T_CRIT_A isactivatedwhen any temperaturereadingisgreaterthanthelimitpresetinthecriticaltemperature setpointregister(T_CRIT),as shown inFigure9.The StatusRegisterscan be read todeterminewhich event caused thealarm.A bitintheStatusRegistersissethightoindicatewhich temperaturereadingexceeded the T_CRIT setpointtemperatureand caused thealarm,see STATUS REGISTER . Localand remotetemperaturediodesaresampled insequence by theA/D converter.The T_CRIT_A outputand theStatusRegisterflagsareupdatedatthecompletionofa conversion.T_CRIT_A and theStatusRegisterflags areresetonlyaftertheStatusRegisterisreadand ifa temperatureconversionisbelow theT_CRIT setpoint,as shown inFigure9.Figure10 shows a simplifiedlogicdiagramoftheT_CRIT_A and relatedcircuitry. *Note:StatusRegisterBitsareresetby a readofStatusRegisterwhere bitislocated. Figure9. T_CRIT_A Temperature Response Diagram
10 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 Figure10. T_CRIT_A outputrelatedcircuitrylogicdiagram Locatedinthe ConfigurationRegisterare the mask bitsforeach temperaturereading,see CONFIGURATION REGISTER .When a mask bitisset,itscorrespondingstatusflagwillnotpropagatetotheT_CRIT_A output,but willstillbe setintheStatusRegisters.ConfigurationregisterbitsD5 and D3, labled“Remote T_CRIT_A mask ” must be sethighbeforetheT_CRIT setpointisloweredinorderfortheT_CRIT_A outputtofunctionproperly. Settingallfourmask bitsorprogrammingtheT_CRIT setpointto127°C willdisabletheT_CRIT_A output. POWER ON RESET DEFAULT STATES LM82 alwayspowers up totheseknown defaultstates: 1. Command Registersetto00h 2. LocalTemperaturesetto0°C 3. Remote Temperaturesetto0°C untiltheLM82 sensesa diodepresentbetween theD+ and D − inputpins. 4. StatusRegistersetto00h. 5. ConfigurationRegistersetto00h;INT enabledand allT_CRIT setpointsenabledtoactivateT_CRIT_A. 6. Localand Remote T_CRIT setto127°C SMBus INTERFACE The LM82 operatesas a slaveon the SMBus, so the SMBCLK lineisan input(no clockisgeneratedby the LM82) and the SMBData lineisbi-directional.Accordingto SMBus specifications,the LM82 has a 7-bitslave address.Bit4 (A3)oftheslaveaddressishardwiredinsidetheLM82 toa 1.The remainderoftheaddressbits arecontrolledby thestateoftheaddressselectpinsADD1 and ADD0, and aresetby connectingthesepinsto groundfora low,(0),toVCC fora high,(1),orleftfloating(TRI-LEVEL). Therefore,thecompleteslaveaddressis: A6 A5 A4 1 A2 A1 A0 MSB LSB and isselectedas follows: Address SelectPin State LM82 SMBus SlaveAddress ADD0 ADD1 A6:A0 binary 0 0 001 1000
0 TRI-LEVEL 001 1001
Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com Address SelectPin State LM82 SMBus SlaveAddress ADD0 ADD1 A6:A0 binary 0 1 001 1010 TRI-LEVEL 0 010 1001 TRI-LEVEL TRI-LEVEL 010 1010 TRI-LEVEL 1 010 1011 1 0 100 1100
1 TRI-LEVEL 100 1101
The LM82 latchesthestateoftheaddressselectpinsduringthefirstreadorwriteon theSMBus. Changing the stateoftheaddressselectpinsafterthefirstreadorwritetoany deviceon theSMBus willnotchange theslave addressoftheLM82. TEMPERATURE DATA FORMAT Temperaturedatacan be readfromtheLocaland Remote Temperature,T_CRIT, and HIGH setpointregisters; and writtento the T_CRIT and HIGH setpointregisters.Temperaturedata isrepresentedby an 8-bit,two's complement bytewithan LSB (LeastSignificantBit)equalto1°C: Temperature DigitalOutput 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 OPEN-DRAIN OUTPUTS The SMBData, INT and T_CRIT_A outputsare open-drainoutputsand do nothave internalpull-ups.A “high” levelwillnotbe observedon thesepinsuntilpull-upcurrentisprovidedfrom some externalsource,typicallya pull-upresistor.Choice of resistorvaluedepends on many system factorsbut,ingeneral,the pull-upresistor shouldbe as largeas possible.Thiswillminimizeany internaltemperaturereadingerrorsdue tointernalheating oftheLM82. The maximum resistanceofthepullup,based on LM82 specificationforHighLevelOutputCurrent, toprovidea 2.1V highlevel,is30kΩ.Care shouldbe takenina noisysystem because a highimpedance pull-up willbe more likelytocouplenoiseintothesignalline. DIODE FAULT DETECTION Beforeeach externalconversiontheLM82 goes throughan externaldiodefaultdetectionsequence.IfD+ input isshortedto VCC or floatingthen the temperaturereadingwillbe +127 °C, and the OPEN bitinthe Status Registerwillbe set.IftheT_CRIT setpointissettolessthan+127 °C thentheD+ inputRTCRIT bitintheStatus Registerwillbe setwhich willactivatetheT_CRIT_A output,ifenabled.Ifa D+ isshortedto GND or D −, its temperaturereadingwillbe 0 °C and itsOPEN bitintheStatusRegisterwillnotbe set.
12 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 COMMUNICATING withtheLM82 There are 13 data registersin the LM82, selectedby the Command Register.At power-up the Command Registerissetto“00”,thelocationfortheRead LocalTemperatureRegister.The Command Registerlatchesthe lastlocationitwas setto.Reading the StatusRegisterresetsT_CRIT_A and INT,so longas a temperature comparison does not signala fault(see INT OUTPUT and T_HIGH LIMITS and T_CRIT_A OUTPUT and T_CRIT LIMIT).Allotherregistersare predefinedas read onlyor writeonly.Read and writeregisterswiththe same functioncontainmirroreddata. A WritetotheLM82 willalwaysincludetheaddressbyteand thecommand byte.A writetoany registerrequires one databyte. Reading theLM82 can takeplaceeitheroftwo ways: 1. IfthelocationlatchedintheCommand Registeriscorrect(mostofthetimeitisexpectedthattheCommand Registerwillpointtoone oftheRead TemperatureRegistersbecause thatwillbe thedatamost frequently read from theLM82), thentheread can simplyconsistofan addressbyte,followedby retrievingthedata byte. 2. IftheCommand Registerneeds tobe set,thenan addressbyte,command byte,repeatstart,and another addressbytewillaccomplisha read. Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com The databytehas themost significantbitfirst.At theend ofa read,theLM82 can accepteitherAcknowledge or No AcknowledgefromtheMaster(No Acknowledgeistypicallyused as a signalfortheslavethattheMasterhas readitslastbyte). SERIAL INTERFACE ERROR RECOVERY The LM82 SMBus lineswillbe resettotheSMBus idlestateiftheSMBData orSMBCLK linesareheldlowfor40 ms or more (tTIMEOUT ).The LM82 may or may not resetthe stateof the serialinterfacelogicifeitherof the SMBData orSMBCLK linesareheldlow between 25 ms and 40 ms. TIMEOUT allowsa cleanrecoveryincases where themastermay be resetwhiletheLM82 istransmittinga lowbitthuspreventingpossiblebus lockup. Whenever theLM82 sees thestartconditionitsserialinterfacewillresettothebeginningofthecommunication, thustheLM82 willexpecttosee an addressbytenext.Thissimplifiesrecoverywhen themasterisresetwhile theLM82 istransmittinga high. LM82 Registers COMMAND REGISTER Selectswhich registerswillbe read from or writtento.Data forthisregistershouldbe transmittedduringthe Command ByteoftheSMBus writecommunication. P7 P6 P5 P4 P3 P2 P1 P0
0 Command Select
P0-P7:Command Select Command Select Power On DefaultState RegisterName RegisterFunction Address <P7:P0> hex <D7:D0> binary <D7:D0> decimal 00h 0000 0000 0 RLT Read LocalTemperature 01h 0000 0000 0 RRT Read Remote Temperature 02h 0000 0000 0 RSR Read StatusRegister 03h 0000 0000 0 RC Read Configuration 04h 0000 0000 0 Reserved 05h 0111 1111 127 RLHS Read LocalHIGH Setpoint 06h Reserved 07h 0111 1111 127 RRHS Read Remote HIGH Setpoint 08h Reserved 09h 0000 0000 WC WriteConfiguration 0Ah Reserved 0Bh 0111 1111 127 WLHS WriteLocalHIGH Setpoint 0Ch Reserved 0Dh 0111 1111 127 WRHS WriteRemote HIGH Setpoint 0Eh-2Fh ReservedforFutureUse 30h-31h 0000 0000 0 Reserved 32h-34h ReservedforFutureUse 35h 0000 0000 0 Reserved 36h-37h ReservedforFutureUse 38h 0111 1111 127 Reserved 39h ReservedforFutureUse 3Ah 0111 1111 127 Reserved 3Bh-41h ReservedforFutureUse 42h 0111 1111 127 RTCS Read T_CRIT Setpoint 43h-4Fh ReservedforFutureUse
14 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 Command Select Power On DefaultState RegisterName RegisterFunction Address <P7:P0> hex <D7:D0> binary <D7:D0> decimal 50h 0111 1111 127 Reserved 51h ReservedforFutureUse 52h 0111 1111 127 Reserved 53h-59h ReservedforFutureUse 5Ah 0111 1111 127 WTCS WriteT_CRIT Setpoint 5Ch-6Fh and F0h- ReservedforFutureUse FDh FEh 0000 0001 1 RMID Read ManufacturersID FFh 0000 0011 3 RSR Read SteppingorDieRevisionCode LOCAL and REMOTE TEMPERATURE REGISTERS (LT,and RT) Table1. LOCAL and REMOTE TEMPERATURE REGISTERS (LT,and RT) (Read Only Address 00h,and 01h): D7 D6 D5 D4 D3 D2 D1 D0 MSB Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 LSB D7 –D0: TemperatureData.One LSB = 1°C. Two'scomplement format. STATUS REGISTER Table2. STATUS REGISTER (Read Only Address 02h): D7 D6 D5 D4 D3 D2 D1 D0
0 LHIGH 0 RHIGH 0 OPEN RCRIT LCRIT
Power up defaultiswithallbits“0”(zero). D0: LCRIT:When settoa 1 indicatesan LocalCriticalTemperaturealarm. D1: RCRIT: When settoa 1 indicatesa Remote DiodeCriticalTemperaturealarm. D2: D2OPEN: When setto1 indicatesa Remote Diodedisconnect. D4: D2RHIGH: When setto1 indicatesa Remote DiodeHIGH Temperaturealarm. D6: LHIGH: When setto1 indicatesa LocalHIGH Temperaturealarm. D7, D5, and D3: These bitsarealwayssetto0 and reservedforfutureuse. MANUFACTURERS ID AND DIE REVISION (Stepping)REGISTERS MANUFACTURERS ID AND DIE REVISION (Stepping)REGISTERS (Read Address FEh and FFh) Default value01h forManufacturersID(FEh). CONFIGURATION REGISTER Table3.CONFIGURATION REGISTER (Read Address 03h/WriteAddress 09h): D7 D6 D5 D4 D3 D2 D1 D0 INT mask 0 Remote Remote Remote Local INT Inversion 0 mask mask mask mask Power up defaultiswithallbits“0”(zero). D7: INT mask: When setto1 INT interruptsaremasked. D5: T_CRIT mask, thisbitmust be setto a 1 beforethe T_CRIT setpointisloweredbelow 127 inorderfor T_CRIT_A pintofunctionproperly. Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com D4: T_CRIT mask forRemote temperature,when setto1 a remote temperaturereadingthatexceeds T_CRIT setpointwillnotactivatetheT_CRIT_A pin. D3: T_CRIT mask, thisbitmust be setto a 1 beforethe T_CRIT setpointisloweredbelow 127 inorderfor T_CRIT_A pintofunctionproperly. D2: T_CRIT mask forLocalreading,when setto1 a Localtemperaturereadingthatexceeds T_CRIT setpoint willnotactivatetheT_CRIT_A pin. D1: INT activestateinversion.When INT Inversionissettoa 1 theactivestateoftheINT outputwillbe a logical high.A lowwouldthenselectan activestateofa logicallow. D6 and D0: These bitsarealwayssetto0 and reservedforfutureuse.A writeof1 willreturna 0 when read. LOCAL AND REMOTE HIGH SETPOINT REGISTERS (LHS,RHS) Table4.LOCAL AND REMOTE HIGH SETPOINT REGISTERS (LHS,RHS) (Read Address 05h,07h/Write Address 0Bh, 0Dh): D7 D6 D5 D4 D3 D2 D1 D0 MSB Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 LSB D7 –D0: HIGH setpointtemperaturedata.Power up defaultisLHIGH = RHIGH=127 °C. T_CRIT REGISTER (TCS) Table5.T_CRIT REGISTER (TCS) (Read Address 42h/WriteAddress 5Ah): D7 D6 D5 D4 D3 D2 D1 D0 MSB Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 LSB D7 –D0: T_CRIT setpointtemperaturedata.Power up defaultisT_CRIT = 127°C.
16 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013 SMBus Timing Diagrams Figure11. (a)SerialBus WritetotheinternalCommand Registerfollowedby a theData Byte Figure12. (b)SerialBus WritetotheinternalCommand Register Figure13. (c)SerialBus Read from a RegisterwiththeinternalCommand Registerpresettodesired value Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 17 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com ApplicationHints The LM82 can be appliedeasilyinthesame way as otherintegrated-circuittemperaturesensorsand itsremote diodesensingcapabilityallowsittobe used innew ways as well.Itcan be solderedtoa printedcircuitboard, and because thepathofbestthermalconductivityisbetween thedieand thepins,itstemperaturewilleffectively be thatoftheprintedcircuitboardlandsand tracessolderedtotheLM82's pins.Thispresumes thattheambient airtemperatureisalmostthesame as thesurfacetemperatureoftheprintedcircuitboard;iftheairtemperature ismuch higherorlowerthanthesurfacetemperature,theactualtemperatureoftheoftheLM82 diewillbe atan intermediatetemperaturebetween thesurfaceand airtemperatures.Again,theprimarythermalconductionpath isthroughtheleads,so thecircuitboardtemperaturewillcontributetothedietemperaturemuch more strongly thanwilltheairtemperature. To measure temperatureexternaltotheLM82's die,use a remotediode.Thisdiodecan be locatedon thedieof a targetIC,allowingmeasurement oftheIC'stemperature,independentoftheLM82's temperature.The LM82 has been optimizedtomeasure theremote diodeofa Pentium IIprocessoras shown inFigure14.A discrete diodecan alsobe used tosense thetemperatureofexternalobjectsor ambientair.Remember thata discrete diode'stemperaturewillbe affected,and oftendominated,by thetemperatureofitsleads. Figure14. Pentium or 3904 Temperature vs LM82 Temperature Reading Most silicondiodesdo notlendthemselveswelltothisapplication.Itisrecommended thata 2N3904 transistor base emitterjunctionbe used withthecollectortiedtothebase. A diodeconnected2N3904 approximatesthe junctionavailableon a Pentium microprocessorfortemperature measurement.Therefore,theLM82 can sense thetemperatureofthisdiodeeffectively. ACCURACY EFFECTS OF DIODE NON-IDEALITY FACTOR The techniqueused intoday'sremote temperaturesensorsisto measure the change inVBE at two different operatingpointsofa diode.Fora biascurrentratioofN:1,thisdifferenceisgivenas: where
- η isthenon-idealityfactoroftheprocessthediodeismanufacturedon,
18 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013
- q istheelectroncharge,
- k istheBoltzmann'sconstant,
- N isthecurrentratio,
- T istheabsolutetemperaturein°K. (1) The temperaturesensorthen measures ΔVBE and convertsto digitaldata.In thisequation,k and q are well defineduniversalconstants,and N is a parameter controlledby the temperaturesensor.The only other parameterisη,whichdepends on thediodethatisused formeasurement.SinceΔVBE isproportionaltobothη and T,thevariationsinη cannotbe distinguishedfromvariationsintemperature.Sincethenon-idealityfactoris notcontrolledby thetemperaturesensor,itwilldirectlyadd totheinaccuracyofthesensor.For thePentium II Intelspecifiesa ±1% variationinη from partto part.As an example,assume a temperaturesensorhas an accuracyspecificationof±3 °C atroom temperatureof25 °C and theprocessused tomanufacturethediode has a non-idealityvariationof±1%. The resultingaccuracyofthetemperaturesensoratroom temperaturewill be: The additionalinaccuracyinthetemperaturemeasurement caused by η,can be eliminatedifeach temperature sensoriscalibratedwiththeremotediodethatitwillbe pairedwith. PCB LAYOUT FOR MINIMIZING NOISE Ina noisyenvironment,such as a processormotherboard,layoutconsiderationsareverycritical.Noiseinduced on tracesrunningbetween the remote temperaturediode sensor and the LM82 can cause temperature conversionerrors.The followingguidelinesshouldbe followed: 1. Placea 0.1μF power supplybypass capacitoras closeas possibletotheVCC pinand therecommended 2.2 nF capacitoras closeas possibletotheD+ and D − pins.Make surethetracestothe2.2nF capacitorare matched. 2. The recommended 2.2nF diode bypass capacitoractuallyhas a range of 200pF to 3.3nF.The average temperatureaccuracywillnot degrade.Increasingthe capacitancewilllowerthe cornerfrequencywhere differentialnoise erroraffectsthe temperaturereadingthus producinga readingthatis more stable. Conversely,loweringthecapacitancewillincreasethecornerfrequencywhere differentialnoiseerroraffects thetemperaturereadingthusproducinga readingthatislessstable. 3. Ideally,theLM82 shouldbe placedwithin10cm oftheProcessordiodepinswiththetracesbeingas straight, shortand identicalas possible.Traceresistanceof1Ω can cause as much as 1°C oferror. 4. Diode tracesshouldbe surroundedby a GND guard ringtoeitherside,above and below ifpossible.This GND guard shouldnotbe between theD+ and D − lines.Intheeventthatnoisedoes coupletothediode linesitwouldbe idealifitiscoupledcommon mode. ThatisequallytotheD+ and D − lines.(SeeFigure15) 5. Avoidroutingdiodetracesincloseproximitytopower supplyswitchingsignalsorfilteringinductors. 6. Avoidrunningdiodetracesclosetoor paralleltohighspeed digitaland bus lines.Diode tracesshouldbe keptatleast2cm. apartfromthehighspeed digitaltraces. 7. Ifitisnecessarytocrosshighspeed digitaltraces,thediodetracesand thehighspeed digitaltracesshould crossata 90 degreeangle. 8. The idealplacetoconnecttheLM82's GND pinisas closeas possibletotheProcessorsGND associated withthesense diode. 9. Leakage currentbetween D+ and GND shouldbe keptto a minimum. One nano-ampere of leakagecan cause as much as 1°C oferrorinthediodetemperaturereading.Keepingtheprintedcircuitboardas clean as possiblewillminimizeleakagecurrent. Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 19 ProductFolderLinks:LM82
SNIS113D –JANUARY 2000–REVISED MARCH 2013 www.ti.com Figure15. IdealDiode Trace Layout Noise couplingintothedigitallinesgreaterthan300mVp-p (typicalhysteresis),overshootgreaterthan500mV above VCC ,and undershootlessthan500mV below GND, may preventsuccessfulSMBus communicationwith the LM82. SMBus no acknowledge isthe most common symptom, causingunnecessarytrafficon the bus. Although,theSMBus maximum frequencyofcommunicationisratherlow (100kHz max) carestillneeds tobe takentoensureproperterminationwithina system withmultiplepartson thebus and longprintedcircuitboard traces.An R/C lowpass filterwitha 3db cornerfrequencyof about 40MHz has been includedon the LM82's SMBCLK input.Additionalresistancecan be added inserieswiththe SMBData and SMBCLK linesto further helpfilternoiseand ringing.Minimizenoisecouplingby keepingdigitaltracesout of switchingpower supply areasas wellas ensuringthatdigitallinescontaininghighspeed datacommunicationscrossatrightanglesto theSMBData and SMBCLK lines.
20 SubmitDocumentationFeedback Copyright© 2000–2013,Texas InstrumentsIncorporated
ProductFolderLinks:LM82
www.ti.com SNIS113D –JANUARY 2000–REVISED MARCH 2013
REVISION HISTORY
Changes from RevisionC (March 2013)toRevisionD Page Copyright© 2000–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 21 ProductFolderLinks:LM82
www.ti.com 15-Dec-2014 Addendum-Page 1 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/Ball Finish (6) MSL Peak Temp (3) Op Temp (°C) Device Marking (4/5) Samples LM82CIMQA/NOPB ACTIVE SSOP DBQ 16 95 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 82CI MQA LM82CIMQAX/NOPB ACTIVE SSOP DBQ 16 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 82CI MQA (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
www.ti.com 15-Dec-2014 Addendum-Page 2 In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. TI assumes no liability for applications assistance or the design of Buyers’products. Buyers are responsible for their products and applications using TI components. To minimize the risks associated with Buyers’products and applications, Buyers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use of any TI components in safety-critical applications. In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and requirements. Nonetheless, such components are subject to these terms. No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties have executed a special agreement specifically governing such use. Only those TI components which TI has specifically designated as military grade or “enhanced plastic”are designed and intended for use in military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of non-designated products, TI will not be responsible for any failure to meet ISO/TS16949. Products Applications Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energy and Lighting www.ti.com/energy Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com OMAP Applications Processors www.ti.com/omap TI E2E Community e2e.ti.com Wireless Connectivity www.ti.com/wirelessconnectivity Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2014, Texas Instruments Incorporated