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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 LM779-Bit+SignDigitalTemperatureSensorandThermalWindowComparatorwith Two-WireInterface Check forSamples: LM77 1FEATURES DESCRIPTION The LM77 isa digitaltemperaturesensorand thermal 2• Window Comparison SimplifiesDesign of window comparatorwithan I2C SerialBus interface.ACPI Compatible Temperature Monitoringand The window-comparatorarchitectureof the LM77Control. eases the design of temperaturecontrolsystems
- SerialBus Interface conformingtotheACPI (AdvancedConfigurationand Power Interface) specificationfor personal• SeparateOpen-Drain Outputs forInterruptand computers.The open-drainInterrupt(INT) outputCriticalTemperature Shutdown becomes activewhenever temperaturegoes outside• Shutdown Mode toMinimizePower a programmable window, whilea separateCriticalConsumption Temperature Alarm (T_CRIT_A) output becomes
- Up to4 LM77s Can be Connected toa Single active when the temperature exceeds a Bus programmable criticallimit.The INT output can operateineithera comparatoror eventmode, while• 9-bit+ Sign Output;Full-ScaleReading ofOver the T_CRIT_A outputoperatesin comparatormode128°C only.• SOIC and VSSOP 8-leadPackages The hostcan program boththeupperand lowerlimits ofthewindow as wellas thecriticaltemperaturelimit.APPLICATIONS Programmable hysterisisas wellas a faultqueue are
- System Thermal Management availabletominimizefalsetripping.Two pins(A0,A1) are availablefor address selection.The sensor• PersonalComputers powers up withdefaultthresholdsof2°C THYST ,10°C• OfficeElectronics TLOW ,64°C THIGH ,and 80°C T_CRIT.• ElectronicTestEquipment The LM77's 3.0V to5.5V supplyvoltagerange,Serial• Automotive Bus interface,9-bit+ signoutput,and full-scalerange
- HVAC of over 128°C make itidealfora wide range of applications.These includethermalmanagement and KEY SPECIFICATIONS protectionapplicationsin personal computers, electronic test equipment, office electronics,• Supply Voltage3.0Vto5.5V automotive,and HVAC applications.• Supply Current – Operating – 250 μA (typ) – 500 μA (max) – Shutdown – 5 μA (typ)
- Temperature Accuracy – −10°C to65°C, ±1.5°C(max) – −25°C to100°C, ±2°C(max) – −55°C to125°C, ±3°C(max) Pleasebe aware thatan importantnoticeconcerningavailability,standardwarranty,and use incriticalapplicationsof Texas Instrumentssemiconductorproductsand disclaimerstheretoappearsattheend ofthisdatasheet. 2Alltrademarksarethepropertyoftheirrespectiveowners. PRODUCTION DATA informationiscurrentas ofpublicationdate. Copyright© 1999–2013,Texas InstrumentsIncorporatedProductsconform to specificationsper the terms of the Texas Instrumentsstandardwarranty.Productionprocessingdoes not necessarilyincludetestingofallparameters.
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com SimplifiedBlock Diagram Figure1. Connection Diagram Figure2. SOIC-8 or VSSOP Package See Package Number D0008A or DGK0008A PIN DESCRIPTIONS Pin Name Pin No. Description TypicalConnection SDA 1 SerialBi-DirectionalData Line.Open DrainOutput From Controller SCL 2 SerialBus ClockInput From Controller T_CRIT_A 3 CriticalTemperatureAlarmOpen DrainOutput PullUp Resistor,ControllerInterruptLineor System Hardware Shutdown GND 4 Power SupplyGround Ground INT 5 InterruptOpen DrainOutput PullUp Resistor,ControllerInterruptLine +VS 8 PositiveSupplyVoltageInput DC Voltagefrom3V to5.5V A0–A1 7,6 User-SetAddressInputs Ground (Low,“0”)or+VS (High,“1”)
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 TypicalApplication Figure3. TypicalApplication These deviceshave limitedbuilt-inESD protection.The leadsshouldbe shortedtogetherorthedeviceplacedinconductivefoam duringstorageorhandlingtopreventelectrostaticdamage totheMOS gates. AbsoluteMaximum Ratings(1) SupplyVoltage −0.3Vto6.5V Voltageatany Pin −0.3Vto(+VS + 0.3V) InputCurrentatany Pin 5 mA Package InputCurrent(2) 20 mA T_CRIT_A and INT OutputSinkCurrent 10 mA T_CRIT_A and INT OutputVoltage 6.5V StorageTemperature −65°C to+125°C SolderingInformation,Lead Temperature ESD Susceptibility(3) Human Body Model 2500V Machine Model 250V Forsolderingspecifications:http://www.ti.com/lit/SNOA549(4) (1) AbsoluteMaximum Ratingsindicatelimitsbeyond whichdamage tothedevicemay occur.DC and AC electricalspecificationsdo not applywhen operatingthedevicebeyond itsratedoperatingconditions. (2) When theinputvoltage(VI)atany pinexceedsthepower supplies(VI< GND orVI> +VS)thecurrentatthatpinshouldbe limitedto5 mA. The 20 mA maximum package inputcurrentratinglimitsthenumber ofpinsthatcan safelyexceed thepower supplieswithan input currentof5 mA tofour. (3) Human body model,100 pF dischargedthrougha 1.5kΩ resistor.Machine model,200 pF dischargeddirectlyintoeach pin. (4) Reflowtemperatureprofilesaredifferentforlead-freeand non-lead-freepackages. OperatingRatings(1)(2) SpecifiedTemperatureRange T MIN toTMAX See (3) −55°C to+125°C SupplyVoltageRange (+VS)(4) +3.0V to+5.5V (1) AbsoluteMaximum Ratingsindicatelimitsbeyond whichdamage tothedevicemay occur.DC and AC electricalspecificationsdo not applywhen operatingthedevicebeyond itsratedoperatingconditions. (2) LM77 θJA (thermalresistance,junction-to-ambient)when attachedtoa printedcircuitboardwith2 oz.foilis:200°C/W fortheSOIC-8 (D0008A)package,250°C/W fortheVSSOP-8 (DGK0008A) package. (3) WhiletheLM77 has a full-scale-rangeinexcessof128°C, prolongedoperationattemperaturesabove 125°C isnotrecommended. (4) Bothpartnumbers oftheLM77 willoperateproperlyoverthe+VS supplyvoltagerangeof3V to5.5V.The devicesaretestedand specifiedforratedaccuracyattheirnominalsupplyvoltage.Accuracywilltypicallydegrade1°C/V ofvariationin+VS as itvariesfrom thenominalvalue. Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 3 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com Temperature-to-DigitalConverterCharacteristics Unlessotherwisenoted,thesespecificationsapplyfor+VS=+5 Vdc ±10% forLM77CIM-5, LM77CIMM-5 and +VS=+3.3Vdc ±10% forLM77CIM-3, LM77CIMM-3 (1).BoldfacelimitsapplyforTA = TJ = TMIN toTMAX ;allotherlimitsTA= TJ=+25°C, unlessotherwisenoted. UnitsParameter TestConditions Typical(2) Limits(3) (Limit) Accuracy TA = −10°C to+65°C ±1.5 TA = −25°C to+100°C ±2.0 °C (max) TA = −55°C to+125°C ±3.0 Resolution See (4) 10 Bits 0.5 °C TemperatureConversionTime See (5) 70 125 ms QuiescentCurrent I2C Inactive 0.25 mA I2C Active 0.25 0.5 mA (max) Shutdown Mode 5 10 μA THYST DefaultTemperature See (6)(7) 2 °C TLOW DefaultTemperature See (7) 10 °C THIGH DefaultTemperature See (7) 64 °C TC DefaultTemperature See (7) 80 °C (1) Bothpartnumbers oftheLM77 willoperateproperlyoverthe+VS supplyvoltagerangeof3V to5.5V.The devicesaretestedand specifiedforratedaccuracyattheirnominalsupplyvoltage.Accuracywilltypicallydegrade1°C/V ofvariationin+VS as itvariesfrom thenominalvalue. (2) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (3) LimitsareguaranteedtoTI's AOQL (AverageOutgoingQualityLevel). (4) 9 bits+ sign,two's complement (5) Thisspecificationisprovidedonlytoindicatehow oftentemperaturedataisupdated.The LM77 can be readatany timewithoutregard toconversionstate(andwillyieldlastconversionresult).Ifa conversionisinprocessitwillbe interruptedand restartedaftertheend of theread. (6) Hysteresisvalueadds totheTLOW setpointvalue(e.g.:ifTLOW setpoint= 10°C, and hysteresis= 2°C, thenactualhysteresispointis 10+2 = 12°C);and subtractsfromtheTHIGH and T_CRIT setpoints(e.g.:ifTHIGH setpoint= 64°C, and hysteresis= 2°C, thenactual hysteresispointis64−2 = 62°C).Fora detaileddiscussionofthefunctionofhysteresisrefertoSection1.1,TEMPERATURE COMPARISON, and Figure7. (7) Defaultvaluessetatpower up. Logic ElectricalCharacteristicsDigitalDC Characteristics Unlessotherwisenoted,thesespecificationsapplyfor+VS=+5 Vdc ±10% forLM77CIM-5, LM77CIMM-5 and +VS=+3.3Vdc ±10% forLM77CIM-3, LM77CIMM-3. BoldfacelimitsapplyforTA = TJ = TMIN toTMAX ;allotherlimitsTA= TJ=+25°C, unless otherwisenoted. UnitsParameter TestConditions Typical(1) Limits(2) (Limit) VIN(1) SDA and SCL Logical“1”InputVoltage +VS × 0.7 V (min) +VS+0.3 V (max) VIN(0) SDA and SCL Logical“0”InputVoltage −0.3 V (min) +VS × 0.3 V (max) VIN(1) A0 and A1 Logical“1”InputVoltage 2.0 V (min) +VS+0.3 V (max) VIN(0) A0 and A1 Logical“0”InputVoltage −0.3 V (min)
0.8 V (max)
IIN(1) Logical“1”InputCurrent VIN = + VS 0.005 1.0 μA (max) IIN(0) Logical“0”InputCurrent VIN = 0V −0.005 −1.0 μA (max) C IN CapacitanceofAllDigitalInputs 20 pF IOH Logic“1”OutputLeakage Current VOH = + VS 10 μA (max) (1) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (2) LimitsareguaranteedtoTI's AOQL (AverageOutgoingQualityLevel).
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 Logic ElectricalCharacteristicsDigitalDC Characteristics(continued) Unlessotherwisenoted,thesespecificationsapplyfor+VS=+5 Vdc ±10% forLM77CIM-5, LM77CIMM-5 and +VS=+3.3Vdc ±10% forLM77CIM-3, LM77CIMM-3. BoldfacelimitsapplyforTA = TJ = TMIN toTMAX ;allotherlimitsTA= TJ=+25°C, unless otherwisenoted. UnitsParameter TestConditions Typical(1) Limits(2) (Limit) VOL Low LevelOutputVoltage IOL = 3 mA 0.4 V (max) T_CRIT_A OutputSaturationVoltage IOUT = 4.0mA (3) 0.8 V (max) T_CRIT_A Delay 1 Conversions (max) tOF OutputFallTime C L = 400 pF 250 ns (max) IO = 3 mA (3) Forbestaccuracy,minimizeoutputloading.Highersinkcurrentscan affectsensoraccuracywithinternalheating.Thiscan cause an errorof0.64°C atfullratedsinkcurrentand saturationvoltagebased on junction-to-ambientthermalresistance. Logic ElectricalCharacteristicsSerialBus DigitalSwitchingCharacteristics Unlessotherwisenoted,thesespecificationsapplyfor+VS=+5 Vdc ±10% forLM77CIM-5 and LM77CIMM-5, +VS=+3.3Vdc ±10% forLM77CIM-3 and LM77CIMM-3, CL (loadcapacitance)on outputlines= 80 pF unlessotherwisespecified.Boldface limitsapplyforTA = TJ = TMIN toTMAX ;allotherlimitsTA = TJ = +25°C, unlessotherwisenoted. UnitsParameter TestConditions Typical(1) Limits(2)(3) (Limit) t1 SCL (Clock)Period 2.5 μs(min) t2 Data inSet-UpTime toSCL High 100 ns(min) t3 Data Out StableafterSCL Low 0 ns(min) t4 SDA Low Set-UpTime toSCL Low (StartCondition) 100 ns(min) t5 SDA HighHoldTime afterSCL High(StopCondition) 100 ns(min) (1) TypicalsareatTA = 25°C and representmost likelyparametricnorm. (2) LimitsareguaranteedtoTI's AOQL (AverageOutgoingQualityLevel). (3) Timingspecificationsaretestedatthebus inputlogiclevels(Vin(0)=0.3xVAfora fallingedge and Vin(1)=0.7xVAfora risingedge)when theSCL and SDA edge ratesaresimilar. Figure4. Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 5 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com Figure5. Temperature-to-DigitalTransferFunction(Non-linearscaleforclarity)
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM77 temperaturesensor incorporatesa band-gap type temperaturesensor,10-bitADC, and a digital comparatorwithuser-programmableupper and lowerlimitvalues.The comparatoractivateseithertheINT line fortemperaturesoutsidethe TLOW and THIGH window, or the T_CRIT_A linefortemperatureswhich exceed T_CRIT. The linesareprogrammableformode and polarity. TEMPERATURE COMPARISON LM77 providesa window comparisonagainsta lower(TLOW ) and upper (THIGH ) trippoint.A second upper trip point(T_CRIT)functionsas a criticalalarmshutdown.Figure7 depictsthecomparisonfunctionas wellas the modes ofoperation. StatusBits The internalStatusbitsoperateas follows: “True”: Temperature above a THIGH or T_CRIT is “true” forthose respectivebits.A “true” forTLOW is temperaturebelowTLOW . “False”: Assuming temperaturehas previouslycrossedabove THIGH or T_CRIT, then the temperaturemust drop below the pointscorrespondingTHYST (THIGH − THYST or T_CRIT − THYST ) inorderforthe conditionto be false.For TLOW ,assuming temperaturehas previouslycrossedbelow TLOW ,a “false” occurswhen temperature goes above TLOW + THYST . The Statusbitsarenotaffectedby readsorany otheractions,and alwaysrepresentthestateoftemperaturevs. setpoints. HardwireOutputs The T_CRIT_A hardwireoutputmirrorsthe T_CRIT_A flagunlessthe partisread.When the flagistrue,the T_CRIT_A outputisassertedregardlessofInterruptMode. Reading theLM77 resetstheT_CRIT_A outputuntil theinternalconversioniscompleted.Ina typicalsystem,T_CRIT_A isused toimmediatelyshutdown or reset thesystem.Thus,once T_CRIT_A assertsthesystemnormallywouldnotbe readingtheLM77 viatheI2C bus. The behavioroftheINT hardwireoutputisas follows: Comparator InterruptMode (Default):User readingpartresetsoutputuntilnextmeasurement completes.If conditionisstilltrue,outputissetagainatend ofnextconversioncycle.For example,ifa userneverreadsthe part,and temperaturegoes below TLOW thenINT becomes active.Itwould staythatway untiltemperaturegoes above TLOW + THYST . However ifthe user reads the part,the outputwould be reset.At the end of the next conversioncycle,iftheconditionistrue,itissetagain.Ifnot,itremainsreset. Event InterruptMode : User readingpartresetsoutputuntilnext condition"event"occurs(inotherwords, outputisonlysetonce fora truecondition,ifresetby a read,itremainsresetuntilthenexttriggeringthreshold has been crossed).Conversely,ifa userneverreadthepart,theoutputwould staysetindefinitelyafterthefirst eventthatsettheoutput.An “event”forEventInterruptMode isdefinedas: 1. Transitioningupward (downward)acrossa setpoint,or 2. Transitioningdownward (upward)acrossa setpoint'scorrespondinghysteresis(afterhavingexceeded that setpoint). For example,ifa userneverreadthepart,and temperaturewent below TLOW thenINT would become active.It wouldstaythatway foreverifa userneverreadthepart. However iftheuserreadthepart,theoutputwouldbe reset.Even iftheconditionistrue,itwillremainreset.The temperaturemust crossabove TLOW + THYST tosettheoutputagain. Ineithermode, readingany registerintheLM77 restartstheconversion.Thisallowsa designertoknow exactly when theLM77 beginsa comparison.ThispreventsunnecessaryInterruptsjustafterreprogrammingsetpoints. Typically,system Interruptinputsare masked priorto reprogrammingtrippoints.By doing a read justafter resettingtrippoints,butpriortounmasking,unexpectedInterruptsareprevented. Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 7 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com Avoid programming setpointsso closethattheirhysteresisvaluesoverlap.An example would be thatwitha THYST valueof2°C thensettingTHIGH and TLOW towithin4°C ofeach otherwillviolatethisrestriction.To be more specific,withTHYST set to 2°C assume THIGH set to 64°C. IfTLOW isset equal to,or higherthan 60°C this restrictionisviolated. DEFAULT SETTINGS The LM77 alwayspowers up ina known state.LM77 power up defaultconditionsare: 1. ComparatorInterruptMode 2. TLOW setto10°C 3. THIGH setto64°C 4. T_CRIT setto80°C 5. THYST setto2°C 6. INT and T_CRIT_A activelow 7. Pointersetto“00”;TemperatureRegister The LM77 registerswillalwaysresettothesedefaultvalueswhen thepower supplyvoltageisbroughtup from zerovoltsas thesupplycrossesthevoltagelevelplottedinthefollowingcurve.The LM77 registerswillreset againwhen thepower supplydropsbelowthevoltageplottedinthiscurve. Average Power on Reset Voltagevs Temperature Figure6. SERIAL BUS INTERFACE The LM77 operatesas a slaveon theSerialBus,so theSCL lineisan input(noclockisgeneratedby theLM77) and theSDA lineisa bi-directionalserialdataline.AccordingtoSerialBus specifications,theLM77 has a 7-bit slaveaddress.The fivemost significantbitsof the slaveaddress are hard wiredinsidethe LM77 and are “10010”. The two leastsignificantbitsof the addressare assignedto pinsA1–A0, and are setby connecting thesepinstogroundfora low,(0);orto+VS fora high,(1). Therefore,thecompleteslaveaddressis: 1 0 0 1 0 A1 A0 MSB LSB
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 Note:EventInterruptmode isdrawn as iftheuserisreadingthepart.Iftheuserdoesn'tread,theoutputswouldgo lowand staythatway untiltheLM77 isread. Figure7. Temperature Response Diagram TEMPERATURE DATA FORMAT Temperaturedata can be read from the Temperatureand Set Pointregisters;and writtento the Set Point registers.Temperaturedata can be read at any time,althoughreadingfasterthan the conversiontimeof the LM77 willpreventdatafrombeingupdated.Temperaturedataisrepresentedby a 10-bit,two'scomplement word withan LSB (LeastSignificantBit)equalto0.5°C: DigitalOutput Temperature Binary Hex +130°C 01 0000 0100 104h +125°C 00 1111 1010 0FAh +25°C 00 0011 0010 032h +0.5°C 00 0000 0001 001h 0°C 00 0000 0000 000h −0.5°C 11 1111 1111 3FFh −25°C 11 1100 1110 3CEh −55°C 11 1001 0010 392h Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 9 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com SHUTDOWN MODE Shutdown mode isenabledby settingtheshutdown bitintheConfigurationregisterviatheSerialBus.Shutdown mode reducespower supplycurrentto5 μA typical.T_CRIT_A isresetifpreviouslyset.Sinceconversionsare stopedduringshutdown,T_CRIT_A and INT willnot be operational.The SerialBus interfaceremainsactive. Activityon theclockand datalinesoftheSerialBus may slightlyincreaseshutdown mode quiescentcurrent. Registerscan be read from and writtento inshutdown mode. The LM77 takesmilisecondsto respond to the shutdowncommand. INT AND T_CRIT_A OUTPUT The INT and T_CRIT_A outputsareopen-drainoutputsand do nothave internalpull-ups.A "high"levelwillnot be observedon thesepinsuntilpull-upcurrentisprovidedfromsome externalsource,typicallya pull-upresistor. Choiceofresistorvaluedepends on many system factorsbut,ingeneral,thepull-upresistorshouldbe as large as possible.Thiswillminimizeany errorsdue tointernalheatingoftheLM77. The maximum allowableresistance ofthepullup resistoris90K Ohms based on theLogic“1”OutputLeakage Currentand a 2 volthighoutputlevel. FAULT QUEUE A faultqueue ofup to4 faultsisprovidedtopreventfalsetrippingwhen theLM77 isused innoisyenvironments. The 4 faultsmust occurconsecutivelyto setflagsas wellas INT and T_CRIT_A outputs.The faultqueue is enabledby settingbit4 oftheConfigurationRegisterhigh(seeTable3). INTERNAL REGISTER STRUCTURE Figure8. The dataregistersintheLM77 are selectedby thePointerregister.At power-upthePointerissetto“00”;the locationfortheTemperatureRegister.The Pointerregisterlatchesthelastlocationitwas setto.InComparator InterruptMode, a read from theLM77 resetstheINT output.PlacingthedeviceinShutdown mode resetsthe INT and T_CRIT_A outputs.Allregistersarereadand write,excepttheTemperatureregisterwhichisreadonly. A writeto the LM77 willalways includethe addressbyteand the Pointerbyte.A writeto the Configuration registerrequiresone databyte,whiletheTLOW ,THIGH ,and T_CRIT registersrequiretwo databytes.
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 Reading theLM77 can takeplaceeitheroftwo ways:IfthelocationlatchedinthePointeriscorrect(mostofthe time itisexpectedthatthe Pointerwillpointto the Temperatureregisterbecause itwillbe the data most frequentlyread from theLM77), thentheread can simplyconsistofan addressbyte,followedby retrievingthe correspondingnumber ofdatabytes.IfthePointerneeds tobe set,thenan addressbyte,pointerbyte,repeat start,and anotheraddressbyteplusrequirednumber ofdatabyteswillaccomplisha read. The firstdata byteisthe most significantbytewithmost significantbitfirst,permittingonlyas much data as necessarytobe readtodeterminethetemperaturecondition.For instance,ifthefirstfourbitsofthetemperature data indicatesa criticalcondition,the hostprocessorcouldimmediatelytakeactionto remedy the excessive temperature.At theend ofa read,theLM77 can accepteitherAcknowledge orNo Acknowledge fromtheMaster (No Acknowledgeistypicallyused as a signalfortheslavethattheMasterhas readitslastbyte). An inadvertent8-bitreadfroma 16-bitregister,withtheD7 bitlow,can cause theLM77 tostopina statewhere theSDA lineisheldlow as shown inFigure9.Thiscan preventany furtherbus communicationuntilatleast9 additionalclockcycleshave occurred.Alternatively,themastercan issueclockcyclesuntilSDA goes high,at whichtimeissuinga “Stop”conditionwillresettheLM77. Figure9. Inadvertent8-BitRead from 16-BitRegisterwhere D7 isZero (“0”) (Selectswhichregisterswillbe readfromorwrittento): Table1.POINTER REGISTER P7 P6 P5 P4 P3 P2 P1 P0 0 0 0 0 0 RegisterSelect P0–P2:RegisterSelect: P2 P1 P0 Register 0 0 0 Temperature(Read only)(Power-updefault) 0 0 1 Configuration(Read/Write) 0 1 0 THYST (Read/Write) 0 1 1 T_CRIT (Read/Write) 1 0 0 TLOW (Read/Write) 1 0 1 THIGH (Read/Write) P3–P7:Must be keptzero. Table2.TEMPERATURE REGISTER (Read Only): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Sign Sign Sign Sign MSB Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 CRIT HIGH LOW StatusBits D0 –D2: StatusBits D3 –D15: TemperatureData.One LSB = 0.5°C. Two'scomplement format. Table3.CONFIGURATION REGISTER (Read/Write): D7 D6 D5 D4 D3 D2 D1 D0 0 0 0 FaultQueue INT Polarity T_CRIT_A INT Mode Shutdown Polarity Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 11 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com D0: Shutdown -When setto1 theLM77 goes tolowpower shutdownmode. Power up defaultof“0”. D1: Interruptmode -0 isComparatorInterruptmode, 1 isEventInterruptmode. Power up defaultof“0”. D2, D3: T_CRIT_A and INT Polarity-0 isactivelow,1 isactivehigh.Outputsareopen-drain.Power up default of“0” D4: FaultQueue -When setto1 theFaultQueue isenabled,see FAULT QUEUE .Power up defaultof“0”. D5 –D7: These bitsareused forproductiontestingand must be keptzerofornormaloperation. Table4.THYST ,TLOW ,THIGH AND T_CRIT_A REGISTERS (Read/Write): D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Sign Sign Sign Sign MSB Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 X X X D0 –D2: Undefined D3 –D15: THYST ,TLOW ,THIGH orT_CRIT TripTemperatureData.Power up defaultisTLOW = 10°C, THIGH = 64°C, T_CRIT = 80°C, THYST = 2°C. THYST issubtractedfromTHIGH ,and T_CRIT, and added toTLOW . Avoidprogrammingsetpointsso closethattheirhysteresisvaluesoverlap.See TEMPERATURE COMPARISON . TEST CIRCUIT DIAGRAMS I2C Timing Diagrams Figure10. Typical2-ByteRead From PresetPointerLocationSuch as Temp or Comparison Registers Figure11. TypicalPointerSet Followed by Immediate Read for2-ByteRegistersuch as Temp or Comparison Registers Figure12. Typical1-ByteRead from ConfigurationRegisterwithPresetPointer
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 Figure13. TypicalPointerSet Followed by Immediate Read from ConfigurationRegister Figure14. ConfigurationRegisterWrite ComparisonRegisterWrite Figure15. Timing Diagrams ApplicationHints The temperatureresponsegraphinFigure16 depictsa typicalapplicationdesignedtomeet ACPI requirements. Inthistypeofapplication,thetemperaturescaleisgivenan arbitraryvalueof"granularity",orthewindow within whichtemperaturenotificationeventsshouldoccur.The LM77 can be programmed tothewindow sizechosen by the designer,and willissueinterruptsto the processorwhenever the window limitshave been crossed.The internalflagspermitquickdeterminationofwhetherthetemperatureisrisingorfalling. The T_CRIT limitwould typicallyuse itsseparateoutputtoactivatehardwareshutdown circuitryseparatefrom theprocessor.Thisisdone because itisexpectedthatiftemperaturehas gottenthishighthattheprocessormay notbe responding.The separatecircuitrycan thenshutdown thesystem,usuallyby shuttingdown thepower supply. Note thattheINT and T_CRIT_A outputsareseparate,butcan be wire-or'dtogether.AlternativelytheT_CRIT_A can be diodeor'dtotheINT lineinsuch a way thata T_CRIT_A eventactivatestheINT line,butan INT event does not activatethe T_CRIT_A line.This may be usefulin the event thatitisdesirableto notifyboth the processorand separateT_CRIT_A shutdown circuitryofa criticaltemperaturealarmatthesame time(maybe theprocessorisstillworkingand can coordinatea gracefulshutdownwiththeseparateshutdowncircuit). To implementACPI compatiblesensingitisnecessaryto sense whenever the temperaturegoes outsidethe window,issuean interrupt,servicetheinterrupt,and reprogramthewindow accordingtothedesiredgranularity ofthetemperaturescale.The reprogrammed window willnow have thecurrenttemperatureinsideit,readyto issuean interruptwhenever thetemperaturedeviatesfromthecurrentwindow. To understandthisgraph,assume thatatthelefthand sidethesystem isatsome nominaltemperature.For the 1steventtemperaturerisesabove theupperwindow limit,THIGH ,causingINT togo active.The system responds to the interruptby queryingthe LM77's statusbitsand determinesthatTHIGH was exceeded,indicatingthat temperatureisrising.The system thenreprogramsthetemperaturelimitstoa valuehigherby an amount equal to the desiredgranularity.Note thatinEvent InterruptMode, reprogrammingthe limitshas caused a second, known, interrupttobe issuedsincetemperaturehas been returnedwithinthewindow.InComparatorInterrupt Mode, theLM77 simplystopsissuinginterrupts. The 2nd eventisanotheridenticalriseintemperature.The 3rdeventistypicalofa dropintemperature.Thisis one oftheconditionsthatdemonstratesthepower oftheLM77, as theuserreceivesnotificationthata lowerlimit isexceeded insuch a way thattemperatureisdropping. Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 13 ProductFolderLinks:LM77
SNIS103F –JUNE 1999–REVISED MARCH 2013 www.ti.com The CriticalAlarm Event activatestheseparateT_CRIT_A output.Typically,thiswould feedcircuitryseparate from theprocessoron theassumptionthatifthesystem reachedthistemperature,theprocessormightnotbe responding. Note:EventInterruptmode isdrawn as iftheuserisreadingthepart.Iftheuserdoesn'tread,theoutputswouldgo lowand staythatway untiltheLM77 isread. Figure16. Temperature Response Diagram forACPI Implementation TypicalApplications Figure17. TypicalApplication
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www.ti.com SNIS103F –JUNE 1999–REVISED MARCH 2013 Figure18. Remote HVAC temperaturesensor communicates via3 wiresincludingthermostatsignals By poweringtheLM77 fromauxilaryoutputofthepower supply,a non-functioningoverheatedcomputercan be powered down topreserveas much ofthesystemas possible. Figure19. ACPI Compatible TerminalAlarm Shutdown Copyright© 1999–2013,Texas InstrumentsIncorporated SubmitDocumentationFeedback 15 ProductFolderLinks:LM77
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REVISION HISTORY
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www.ti.com 1-Nov-2013 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 LM77CIM-3 NRND SOIC D 8 95 TBD Call TI Call TI -55 to 125 LM77 CIM-3 LM77CIM-3/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 LM77 CIM-3 LM77CIM-5/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 LM77 CIM-5 LM77CIMM-3/NOPB ACTIVE VSSOP DGK 8 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 T06C LM77CIMM-5/NOPB ACTIVE VSSOP DGK 8 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 T07C LM77CIMMX-3/NOPB ACTIVE VSSOP DGK 8 3500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 T06C LM77CIMMX-5/NOPB ACTIVE VSSOP DGK 8 3500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 T07C LM77CIMX-3 NRND SOIC D 8 2500 TBD Call TI Call TI -55 to 125 LM77 CIM-3 LM77CIMX-3/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 LM77 CIM-3 LM77CIMX-5/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -55 to 125 LM77 CIM-5 (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)
www.ti.com 1-Nov-2013 Addendum-Page 2 (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. 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.
*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W1 (mm) (mm) (mm) (mm) (mm) W (mm) Pin1 Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 Pack Materials-Page 1
*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM77CIMM-3/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM77CIMM-5/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM77CIMMX-3/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM77CIMMX-5/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0 LM77CIMX-3 SOIC D 8 2500 367.0 367.0 35.0 LM77CIMX-3/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM77CIMX-5/NOPB SOIC D 8 2500 367.0 367.0 35.0 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 Pack Materials-Page 2
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