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LM75 (1).pdf

LM75 (1).pdf

上传者: hdingguo 2012-04-02 评分 0 0 0 0 0 0 暂无简介 简介 举报

简介:本文档为《LM75 (1)pdf》,可适用于IT/计算机领域,主题内容包含LMDigitalTemperatureSensorandThermalWatchdogwithTwoWireInterfaceGeneralDes符等。

LMDigitalTemperatureSensorandThermalWatchdogwithTwoWireInterfaceGeneralDescriptionTheLMisatemperaturesensor,DeltaSigmaanalogtodigitalconverter,anddigitalovertemperaturedetectorwithICinterfaceThehostcanquerytheLMatanytimetoreadtemperatureTheopendrainOvertemperatureShutdown(OS)outputbecomesactivewhenthetemperatureexceedsaprogrammablelimitThispincanoperateineither“Comparator”or“Interrupt”modeThehostcanprogramboththetemperaturealarmthreshold(TOS)andthetemperatureatwhichthealarmconditiongoesaway(THYST)Inaddition,thehostcanreadbackthecontentsoftheLM’sTOSandTHYSTregistersThreepins(A,A,A)areavailableforaddressselectionThesensorpowersupinComparatormodewithdefaultthresholdsofCTOSandCTHYSTTheLM’sVtoVsupplyvoltagerange,lowsupplycurrentandICinterfacemakeitidealforawiderangeofapplicationsTheseincludethermalmanagementandprotectionapplicationsinpersonalcomputers,electronictestequipment,andofficeelectronicsFeaturesnSOPandMiniSOP(MSOP)packagessavespacenICBusinterfacenSeparateopendrainoutputpinoperatesasinterruptorcomparatorthermostatoutputnRegisterreadbackcapabilitynPowerupdefaultspermitstandaloneoperationasthermostatnShutdownmodetominimizepowerconsumptionnUptoLMscanbeconnectedtoasinglebusnULRecognizedComponentKeySpecificationsjSupplyVoltageVtoVjSupplyCurrentoperatingµA(typ)mA(max)shutdownµA(typ)jTemperatureAccuracyCtoCC(max)CtoCC(max)ApplicationsnSystemThermalManagementnPersonalComputersnOfficeElectronicsnElectronicTestEquipmentSimplifiedBlockDiagramICisaregisteredtrademarkofPhilipsCorporationFebruaryLMDigitalTemperatureSensorandThermalWatchdogwithTwoWireInterfaceNationalSemiconductorCorporationDSwwwnationalcomConnectionDiagramSOPandMiniSOPOrderingInformationOrderNumberPackageMarkingNSPackageNumberSupplyVoltageTransportMediaNoiseFilteronSDAandSCLLMBIMLMBIMMA(SOP)VUnitsinRailYesLMBIMXLMBIMMA(SOP)VUnitsonTapeandReelYesLMBIMMTBMUAA(MSOP)VUnitsonTapeandReelYesLMBIMMXTBMUAA(MSOP)VUnitsonTapeandReelYesLMBIMLMBIMMA(SOP)VUnitsinRailYesLMBIMXLMBIMMA(SOP)VUnitsonTapeandReelYesLMBIMMTBMUAA(MSOP)VUnitsonTapeandReelYesLMBIMMXTBMUAA(MSOP)VUnitsonTapeandReelYesLMCIMLMCIMMA(SOP)VUnitsinRailNotAvailableLMCIMXLMCIMMA(SOP)VUnitsonTapeandReelNotAvailableLMCIMMTCMUAA(MSOP)VUnitsonTapeandReelNotAvailableLMCIMMXTCMUAA(MSOP)VUnitsonTapeandReelNotAvailableLMCIMLMCIMMA(SOP)VUnitsinRailNotAvailableLMCIMXLMCIMMA(SOP)VUnitsonTapeandReelNotAvailableLMCIMMTCMUAA(MSOP)VUnitsonTapeandReelNotAvailableLMCIMMXTCMUAA(MSOP)VUnitsonTapeandReelNotAvailablePinDescriptionLabelPin#FunctionTypicalConnectionSDAICSerialBiDirectionalDataLineOpenDrainFromController,tiedtoapullupSCLICClockInputFromControllerOSOvertemperatureShutdownOpenDrainOutputPull–upResistor,ControllerInterruptLineGNDPowerSupplyGroundGroundVSPositiveSupplyVoltageInputDCVoltagefromVtoVµFbypasscapacitorwithµFbulkcapacitanceinthenearvicinityA–A,,UserSetICAddressInputsGround(Low,“”)orVS(High,“”)LMwwwnationalcomPinDescription(Continued)FIGURETypicalApplicationLMwwwnationalcomAbsoluteMaximumRatings(Note)SupplyVoltageVtoVVoltageatanyPinVtoVSVInputCurrentatanyPin(Note)mAPackageInputCurrent(Note)mAOSOutputSinkCurrentmAOSOutputVoltageVStorageTemperatureCtoCSolderingInformation,LeadTemperatureSOPandMSOPPackage(Note)VaporPhase(seconds)Infrared(seconds)CCESDSusceptibility(Note)LMBLMCHumanBodyModelVVMachineModelVVOperatingRatingsSpecifiedTemperatureRangeTMINtoTMAX(Note)CtoCSupplyVoltageRange(VS)VtoVTemperaturetoDigitalConverterCharacteristicsUnlessotherwisenoted,thesespecificationsapplyforVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMMandVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMM(Note)BoldfacelimitsapplyforTA=TJ=TMINtoTMAXallotherlimitsTA=TJ=C,unlessotherwisenotedParameterConditionsTypical(Note)Limits(Note)Units(Limit)AccuracyTA=CtoCC(max)TA=CtoCC(max)ResolutionBitsTemperatureConversionTime(Note)msQuiescentCurrentLMBICInactivemA(max)ShutdownMode,VS=VµAShutdownMode,VS=VµALMCICInactivemA(max)ShutdownMode,VS=VµAShutdownMode,VS=VµAOSOutputSaturationVoltageIOUT=mAV(max)(Note)OSDelay(Note)Conversions(min)Conversions(max)TOSDefaultTemperature(Note)CTHYSTDefaultTemperature(Note)CLogicElectricalCharacteristicsDIGITALDCCHARACTERISTICSUnlessotherwisenoted,thesespecificationsapplyforVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMMandVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMM(Note)BoldfacelimitsapplyforTA=TJ=TMINtoTMAXallotherlimitsTA=TJ=C,unlessotherwisenotedSymbolParameterConditionsTypical(Note)Limits(Note)Units(Limit)VIN()Logical“”InputVoltageVSxV(min)VSV(max)VIN()Logical“”InputVoltageV(min)VSxV(max)IIN()Logical“”InputCurrentVIN=VµA(max)IIN()Logical“”InputCurrentVIN=VµA(max)CINAllDigitalInputspFIOHHighLevelOutputCurrentVOH=VµA(max)VOLLowLevelOutputVoltageIOL=mAV(max)tOFOutputFallTimeCL=pFns(max)LMwwwnationalcomLogicElectricalCharacteristics(Continued)DIGITALDCCHARACTERISTICSUnlessotherwisenoted,thesespecificationsapplyforVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMMandVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMM(Note)BoldfacelimitsapplyforTA=TJ=TMINtoTMAXallotherlimitsTA=TJ=C,unlessotherwisenotedSymbolParameterConditionsTypical(Note)Limits(Note)Units(Limit)IO=mAICDIGITALSWITCHINGCHARACTERISTICSUnlessotherwisenoted,thesespecificationsapplyforVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMMandVS=VdcforLMBIM,LMBIMM,LMCIM,andLMCIMMCL(loadcapacitance)onoutputlines=pFunlessotherwisespecifiedBoldfacelimitsapplyforTA=TJ=TMINtoTMAXallotherlimitsTA=TJ=C,unlessotherwisenotedTheswitchingcharacteristicsoftheLMfullymeetorexceedthepublishedspecificationsoftheICbusThefollowingparametersarethetimingrelationshipsbetweenSCLandSDAsignalsrelatedtotheLMTheyarenottheICbusspecificationsSymbolParameterConditionsTypical(Note)Limits(Note)Units(Limit)tSCL(Clock)Periodµs(min)tDatainSetUpTimetoSCLHighns(min)tDataOutStableafterSCLLowns(min)tSDALowSetUpTimetoSCLLow(StartCondition)ns(min)tSDAHighHoldTimeafterSCLHigh(StopCondition)ns(min)tTIMEOUTSDATimeLowforResetofSerialInterface(Note)LMBms(min)ms(max)LMCNotApplicableNote:AbsoluteMaximumRatingsindicatelimitsbeyondwhichdamagetothedevicemayoccurDCandACelectricalspecificationsdonotapplywhenoperatingthedevicebeyonditsratedoperatingconditionsNote:Whentheinputvoltage(VI)atanypinexceedsthepowersupplies(VI<GNDorVI>VS)thecurrentatthatpinshouldbelimitedtomAThemAmaximumpackageinputcurrentratinglimitsthenumberofpinsthatcansafelyexceedthepowersupplieswithaninputcurrentofmAtofourNote:SeeAN“SurfaceMountingMethodsandTheirEffectonProductReliability”orthesectiontitled“SurfaceMount”foundinacurrentNationalSemiconductorLinearDataBookforothermethodsofsolderingsurfacemountdevicesNote:Humanbodymodel,pFdischargedthroughakΩresistorMachinemodel,pFdischargeddirectlyintoeachpinLMwwwnationalcomNote:LMθJA(thermalresistance,junctiontoambient)whenattachedtoaprintedcircuitboardwithozfoilsimilartotheoneshowninFigureissummarizedinthetablebelow:DeviceNumberNSPackageNumberThermalResistance(θJA)LMBIM,LMBIM,LMCIM,LMCIMMACWLMBIMM,LMBIMM,LMCIMM,LMCIMMMUAACWNote:AllpartnumbersoftheLMwilloperateproperlyovertheVSsupplyvoltagerangeofVtoVThedevicesaretestedandspecifiedforratedaccuracyattheirnominalsupplyvoltageAccuracywilltypicallydegradeCVofvariationinVSasitvariesfromthenominalvalueNote:LimitsareguaranteedtoNational’sAOQL(AverageOutgoingQualityLevel)Note:ThisspecificationisprovidedonlytoindicatehowoftentemperaturedataisupdatedTheLMcanbereadatanytimewithoutregardtoconversionstate(andwillyieldlastconversionresult)IfaconversionisinprocessitwillbeinterruptedandrestartedaftertheendofthereadNote:Forbestaccuracy,minimizeoutputloadingHighersinkcurrentscanaffectsensoraccuracywithinternalheatingThiscancauseanerrorofCatfullratedsinkcurrentandsaturationvoltagebasedonjunctiontoambientthermalresistanceNote:OSDelayisuserprogrammableupto“overlimit”conversionsbeforeOSissettominimizefalsetrippinginnoisyenvironmentsNote:DefaultvaluessetatpowerupNote:TypicalsareatTA=CandrepresentmostlikelyparametricnormNote:HoldingtheSDAlinelowforatimegreaterthantTIMEOUTwillcausetheLMBtoresetSDAtotheIDLEstateoftheserialbuscommunication(SDAsetHigh)FIGURETemperaturetoDigitalTransferFunction(Nonlinearscaleforclarity)LMwwwnationalcomTypicalPerformanceCharacteristicsStaticQuiescentCurrentvsTemperatureDynamicQuiescentCurrentvsTemperatureAccuracyvsTemperatureFunctionalDescriptionTheLMtemperaturesensorincorporatesabandgaptypetemperaturesensorandbitADC(DeltaSigmaAnalogtoDigitalConverter)ThetemperaturedataoutputoftheLMisavailableatalltimesviatheICbusIfaconversionisinprogress,itwillbestoppedandrestartedafterthereadAdigitalcomparatorisalsoincorporatedthatcomparesaseriesofreadings,thenumberofwhichisuserselectable,touserprogrammablesetpointandhysteresisvaluesThecomparatortripstheOSoutputline,whichisprogrammableformodeandpolarityTheLMBcontainsallthefunctionalityoftheLMC,plustwoadditionalfeatures:TheLMBhasanintegratedlowpassfilteronboththeSDAandtheSCLlineThesefiltersincreasecommunicationsreliabilityinnoisyenvironmentsTheLMBalsohasabusfaulttimeoutfeatureIftheSDAlineisheldlowforlongerthantTIMEOUT(msminimumtomsmaximum)theLMBwillresettotheIDLEstate(SDAsettohighimpedance)andwaitforanewstartconditionOSOUTPUT,TOSANDTHYSTLIMITSInComparatormodetheOSOutputbehaveslikeathermostatTheoutputbecomesactivewhentemperatureexceedstheTOSlimit,andleavestheactivestatewhenthetemperaturedropsbelowtheTHYSTlimitInthismodetheOSoutputcanbeusedtoturnacoolingfanon,initiateanemergencysystemshutdown,orreducesystemclockspeedShutdownmodedoesnotresetOSstateinacomparatormodeInInterruptmodeexceedingTOSalsomakesOSactivebutOSwillremainactiveindefinitelyuntilresetbyreadinganyregisterviatheICinterfaceOnceOShasbeenactivatedFIGUREPrintedCircuitBoardUsedforThermalResistanceSpecificationsLMwwwnationalcomFunctionalDescription(Continued)bycrossingTOS,thenreset,itcanbeactivatedagainonlybyTemperaturegoingbelowTHYSTAgain,itwillremainactiveindefinitelyuntilbeingresetbyareadPlacingtheLMinshutdownmodealsoresetstheOSOutputPOWERUPANDPOWERDOWNTheLMalwayspowersupinaknownstateThepowerupdefaultconditionsare:ComparatormodeTOS=CTHYST=COSactivelowPointer=“”IftheLMisnotconnectedtotheICbusonpowerup,itwillactasastandalonethermostatwiththeabovetemperaturesettingsWhenthesupplyvoltageislessthanaboutV,theLMisconsideredpowereddownAsthesupplyvoltagerisesabovethenominalVpowerupthreshold,theinternalregistersareresettothepowerupdefaultvalueslistedaboveICBUSINTERFACETheLMoperatesasaslaveontheICbus,sotheSCLlineisaninput(noclockisgeneratedbytheLM)andtheSDAlineisabidirectionalserialdatapathAccordingtoICbusspecifications,theLMhasabitslaveaddressThefourmostsignificantbitsoftheslaveaddressarehardwiredinsidetheLMandare“”ThethreeleastsignificantbitsoftheaddressareassignedtopinsA–A,andaresetbyconnectingthesepinstogroundforalow,()ortoVSforahigh,()Therefore,thecompleteslaveaddressis:AAAMSBLSBNote:TheseinterruptmoderesetsofOSoccuronlywhenLMisreadorplacedinshutdownOtherwise,OSwouldremainactiveindefinitelyforanyeventFIGUREOSOutputTemperatureResponseDiagramLMwwwnationalcomFunctionalDescription(Continued)TEMPERATUREDATAFORMATTemperaturedatacanbereadfromtheTemperature,TOSSetPoint,andTHYSTSetPointregistersandwrittentotheTOSSetPoint,andTHYSTSetPointregistersTemperaturedataisrepresentedbyabit,two’scomplementwordwithanLSB(LeastSignificantBit)equaltoC:TemperatureDigitalOutputBinaryHexCFAhChChChCFFhCCEhChSHUTDOWNMODEShutdownmodeisenabledbysettingtheshutdownbitintheConfigurationregisterviatheICbusShutdownmodereducespowersupplycurrenttoµAtypicalInInterruptmodeOSisresetifpreviouslysetandisundefinedinComparatormodeduringshutdownTheICinterfaceremainsactiveActivityontheclockanddatalinesoftheICbusmayslightlyincreaseshutdownmodequiescentcurrentTOS,THYST,andConfigurationregisterscanbereadfromandwrittentoinshutdownmodeFAULTQUEUEAfaultqueueofuptofaultsisprovidedtopreventfalsetrippingofOSwhentheLMisusedinnoisyenvironmentsThenumberoffaultssetinthequeuemustoccurconsecutivelytosettheOSoutputCOMPARATORINTERRUPTMODEAsindicatedintheOSOutputTemperatureResponseDiagram,Figure,theeventsthattriggerOSareidenticalforeitherComparatororInterruptmodeThemostimportantdifferenceisthatinInterruptmodetheOSwillremainsetindefinitelyonceithasbeensetToresetOSwhileinInterruptmode,performareadfromanyregisterintheLMOSOUTPUTTheOSoutputisanopendrainoutputanddoesnothaveaninternalpullupA“high”levelwillnotbeobservedonthispinuntilpullupcurrentisprovidedfromsomeexternalsource,typicallyapullupresistorChoiceofresistorvaluedependsonmanysystemfactorsbut,ingeneral,thepullupresistorshouldbeaslargeaspossibleThiswillminimizeanyerrorsduetointernalheatingoftheLMThemaximumresistanceofthepullup,basedonLMspecificationforHighLevelOutputCurrent,toprovideaVhighlevel,iskΩOSPOLARITYTheOSoutputcanbeprogrammedviatheconfigurationregistertobeeitheractivelow(defaultmode),oractivehighInactivelowmodetheOSoutputgoeslowwhentriggeredexactlyasshownontheOSOutputTemperatureResponseDiagram,FigureActivehighsimplyinvertsthepolarityoftheOSoutputLMwwwnationalcomFunctionalDescription(Continued)INTERNALREGISTERSTRUCTURETherearefourdataregistersintheLM,selectedbythePointerregisterAtpowerupthePointerissetto“”thelocationfortheTemperatureRegisterThePointerregisterlatcheswhateverthelastlocationitwassettoInInterruptMode,areadfromtheLM,orplacingthedeviceinshutdownmode,resetstheOSoutputAllregistersarereadandwrite,excepttheTemperatureregisterwhichisreadonlyAwritetotheLMwillalwaysincludetheaddressbyteandthePointerbyteAwritetotheConfigurationregisterrequiresonedatabyte,andtheTOSandTHYSTregistersrequiretwodatabytesReadingtheLMcantakeplaceeitheroftwoways:IfthelocationlatchedinthePointeriscorrect(mostofthetimeitisexpectedthatthePointerwillpointtotheTemperatureregisterbecauseitwillbethedatamostfrequentlyreadfromtheLM),thenthereadcansimplyconsistofanaddressbyte,followedbyretrievingthecorrespondingnumberofdatabytesIfthePointerneedstobeset,thenanaddressbyte,pointerbyte,repeatstart,andanotheraddressbytewillaccomplishareadThefirstdatabyteisthemostsignificantbytewithmostsignificantbitfirst,permittingonlyasmuchdataasnecessarytobereadtodeterminetemperatureconditionForinstance,ifthefirstfourbitsofthetemperaturedataindicatesanovertemperaturecondition,thehostprocessorcouldimmediatelytakeactiontoremedytheexcessivetemperaturesAttheendofaread,theLMcanaccepteitherAcknowledgeorNoAcknowledgefromtheMaster(NoAcknowledgeistypicallyusedasasignalfortheslavethattheMasterhasreaditslastbyte)Aninadvertentbitreadfromabitregister,withtheDbitlow,cancausetheLMtostopinastatewheretheSDAlineisheldlowasshowninFigureThiscanpreventanyfurtherbuscommunicationuntilatleastadditionalclockcycleshaveoccurredAlternatively,themastercanissueclockcyclesuntilSDAgoeshigh,atwhichtimeissuinga“Stop”conditionwillresettheLMFIGUREInadvertentBitReadfromBitRegisterwhereDisZero(“”)LMwwwnationalcomFunctionalDescription(Continued)POINTERREGISTER(Selectswhichregisterswillbereadfromorwrittento):PPPPPPPPRegisterSelectPP:RegisterSelect:PPRegisterTemperature(Readonly)(Powerupdefault)Configuration(ReadWrite)THYST(ReadWrite)TOS(ReadWrite)P–P:MustbekeptzeroTEMPERATUREREGISTER(ReadOnly):DDDDDDDDDDDDDDDDMSBBitBitB

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