receive4444yy.com

2013MicrochipTechnologyInc.
DS20005192B-page1MCP9844Features:1MHz,2-WireI2CInterfaceUser-SelectableMeasurementResolution:-+0.
5°C,+0.
25°C,+0.
125°C,+0.
0625°CUser-ProgrammableTemperatureLimits:-TemperatureWindowLimit-CriticalTemperatureLimitUser-ProgrammableTemperatureAlertOutputSpecifiedVDDRange:1.
7Vto3.
6VOperatingCurrent:100A(typical)AvailablePackage:8-PinTDFNTemperatureSensorFeatures:Temperature-to-DigitalConverter(°C)SensorAccuracy:-±0.
2°C/±1°C(typ.
/max.
)+75°Cto+95°C-±0.
5°C/±2°C(typ.
/max.
)+40°Cto+125°C-±1°C/±3°C(typ.
/max.
)-40°Cto+125°CTypicalApplications:TemperatureSensingforSolidStateDrive(SSD)GeneralPurposeTemperatureDatalogGeneralPurposeIndustrialApplicationsIndustrialFreezersandRefrigeratorsFoodProcessingPersonalComputersandServersPCPeripheralsConsumerElectronicsHandheld/PortableDevicesDescription:MicrochipTechnologyInc.
'sMCP9844digitaltemperaturesensorconvertstemperaturefrom-40°Cto+125°Ctoadigitalword.
Itprovidesanaccuracyof±0.
2°C/±1°C(typical/maximum)from+75°Cto+95°Cwithanoperatingvoltageof1.
7Vto3.
6V.
TheMCP9844digitaltemperaturesensorcomeswithuser-programmableregistersthatprovideflexibilityfortemperaturesensingapplications.
Theregistersallowuser-selectablesettingssuchasShutdownorLow-Powermodes,andthespecificationoftemperatureeventboundaries.
Whenthetemperaturechangesbeyondthespecifiedeventboundarylimits,theMCP9844outputsanAlertsignalattheEventpin.
Theuserhastheoptionofsettingthetemperatureeventoutputsignalpolarityaseitheranactive-loworactive-highcomparatoroutputforthethermostatoperation,orasatemperatureeventinterruptoutputformicroprocessor-basedsystems.
ThissensorhasanindustrystandardI2CFastModePluscompatible1MHzserialinterface.
PackageTypes-3.
0-2.
0-1.
00.
01.
02.
03.
0-40-20020406080100120TemperatureAccuracy(°C)TA(°C)VDD=1.
7Vto3.
6V16unitsSpec.
Limits+Std.
Dev.
Average-Std.
Dev.
8-Pin2x3TDFN**IncludesExposedThermalPad(EP);seeTable3-1.
SCLEventSDAA1A212348765GNDA0VDDEP9±1°CAccurate,1.
8VDigitalTemperatureSensorMCP9844DS20005192B-page22013MicrochipTechnologyInc.
1.
0ELECTRICALCHARACTERISTICSAbsoluteMaximumRatingsVDD.
4.
0VVoltageatallInput/OutputpinsGND–0.
3Vto4.
0VPinA0.
GND–0.
3Vto11VStoragetemperature65°Cto+150°CAmbienttemp.
withpowerapplied40°Cto+125°CJunctionTemperature(TJ)150°CESDprotectiononallpins(HBM:MM)4kV:200V)Latch-UpCurrentateachpin(25°C)200mANotice:Stressesabovethoselistedunder"Maximumratings"maycausepermanentdamagetothedevice.
Thisisastressratingonlyandfunctionaloperationofthedeviceatthoseoranyotherconditionsabovethoseindicatedintheoperationallistingsofthisspecificationisnotimplied.
Exposuretomaximumratingconditionsforextendedperiodsmayaffectdevicereliability.
TEMPERATURESENSORDCCHARACTERISTICSElectricalSpecifications:Unlessotherwiseindicated,VDD=1.
7Vto3.
6V,GND=Ground,andTA=-40°Cto+125°C.
ParametersSym.
Min.
Typ.
Max.
UnitConditionsTemperatureSensorAccuracy+75°CVIHInputImpedance(A0,A1,A2)ZIN—200—kVINtOUT,thetemperaturesensorI2Cinterfacewilltimeout.
ARepeatStartcommandisrequiredforcommunication.
3:ThisdevicecanbeusedinaStandardmodeI2Cbussystem,buttherequirementtSU:DAT250nsmustbemet.
ThisdevicedoesnotstretchSCLLowperiod.
ItoutputsthenextdatabittotheSDAlinewithintRMAX+tSU:DATMIN=1000ns+250ns=1250ns(accordingtotheStandardmodeI2Cbusspecification)beforetheSCLlineisreleased.
4:Asatransmitter,thedeviceprovidesinternalminimumdelaytimetHD:DATMINtobridgetheundefinedregion(min.
200ns)ofthefallingedgeofSCLtFMAXtoavoidunintendedgenerationofStartorStopconditions.
5:Characterizedbutnotproductiontested.
6:Asareceiver,SDAshouldnotbesampledatthefallingedgeofSCL.
SDAcantransitiontHD:DI0nsafterSCLtogglesLow.
tSU:STOtSU:DItSU:DItSU:STOtB:FREESCLSDAtHD:DI/tHD:DOtHIGHtLOWtOUTtR,tFStartConditionDataTransmissionStopCondition2013MicrochipTechnologyInc.
DS20005192B-page5MCP98442.
0TYPICALPERFORMANCECURVESNote:Unlessotherwiseindicated,VDD=1.
7Vto3.
6V,GND=Ground,SDA/SCLpulled-uptoVDD,andTA=-40°Cto+125°C.
FIGURE2-1:TemperatureAccuracy.
FIGURE2-2:TemperatureAccuracyHistogram,TA=+85°C.
FIGURE2-3:TemperatureAccuracyHistogram,TA=+25°C.
FIGURE2-4:SupplyCurrentVs.
Temperature.
FIGURE2-5:ShutdownCurrentVs.
Temperature.
FIGURE2-6:Power-OnResetThresholdVoltageVs.
Temperature.
Note:Thegraphsandtablesprovidedfollowingthisnoteareastatisticalsummarybasedonalimitednumberofsamplesandareprovidedforinformationalpurposesonly.
Theperformancecharacteristicslistedhereinarenottestedorguaranteed.
Insomegraphsortables,thedatapresentedmaybeoutsidethespecifiedoperatingrange(e.
g.
,outsidespecifiedpowersupplyrange)andthereforeoutsidethewarrantedrange.
-3.
0-2.
0-1.
00.
01.
02.
03.
0-40-20020406080100120TemperatureAccuracy(°C)TA(°C)VDD=1.
7Vto3.
6V16unitsSpec.
Limits+Std.
Dev.
Average-Std.
Dev.
25%50%75%100%OccurrencesTA=+85°CVDD=1.
7V-3.
6V16units0%-1.
00-0.
75-0.
50-0.
250.
000.
250.
500.
751.
00TemperatureAccuracy(°C)25%50%75%100%OccurrencesTA=+25°CVDD=1.
7V-3.
6V16units0%-1.
00-0.
75-0.
50-0.
250.
000.
250.
500.
751.
00TemperatureAccuracy(°C)75100125150IDD(A)5075-40-20020406080100120TA(°C)0250.
500.
751.
00ISHDN(A)0.
000.
25-40-20020406080100120TA(°C)11.
21.
41.
61.
8VPOR(V)FallingVDDRisingVDD0.
60.
8-40-20020406080100120TA(°C)MCP9844DS20005192B-page62013MicrochipTechnologyInc.
Note:Unlessotherwiseindicated,VDD=1.
7Vto3.
6V,GND=Ground,SDA/SCLpulled-uptoVDD,andTA=-40°Cto+125°C.
FIGURE2-7:EventOutputandSDAVOLVs.
Temperature.
FIGURE2-8:TemperatureConversionRateVs.
Temperature.
FIGURE2-9:SDAIOLVs.
Temperature.
FIGURE2-10:LineRegulation:ChangeinTemperatureAccuracyVs.
ChangeinVDD.
FIGURE2-11:I2CProtocolTime-outVs.
Temperature.
010.
20.
30.
4ent&SDAVOL(V)SDA,IOL=20mAVDD=2.
2Vto3.
6V00.
1-40-20020406080100120EveTA(°C)Event,IOL=3mA5075100125150175200tCONV(ms)0.
0625°C/LSb0.
125°C/LSb02550-40-20020406080100120TA(°C)0.
25°C/LSb0.
5°C/LSb20304050SDAIOL(mA)VOL=0.
6V1020-40-20020406080100120TA(°C)-1.
00.
01.
02.
03.
0lizedTemp.
Error(°C)VDD=1.
7VVDD=3.
6V-3.
0-2.
0-40-20020406080100120NormalTA(°C)3035CBustOUT(ms)25-40-20020406080100120I2CTA(°C)2013MicrochipTechnologyInc.
DS20005192B-page7MCP98443.
0PINDESCRIPTIONThedescriptionsofthepinsarelistedinTable3-1.
TABLE3-1:PINFUNCTIONTABLES3.
1AddressPins(A0,A1,A2)Thesepinsaredeviceaddressinputpins.
TheaddresspinscorrespondtotheLeastSignificantbits(LSb)oftheaddressbits.
TheMostSignificantbits(MSb)areA6,A5,A4,A3.
RefertoTable3-2.
Alladdresspinshaveaninternalpull-downresistor.
3.
2GroundPin(GND)TheGNDpinisthesystemgroundpin.
3.
3SerialDataLine(SDA)TheSDAisabidirectionalinput/outputpinusedtoseriallytransmitdatato/fromthehostcontroller.
Thispinrequiresapull-upresistor.
(SeeSection4.
0"SerialCommunication".
)3.
4SerialClockLine(SCL)TheSCLisaclockinputpin.
Allcommunicationandtimingisrelativetothesignalonthispin.
Theclockisgeneratedbythehostormastercontrolleronthebus.
(SeeSection4.
0"SerialCommunication".
)3.
5TemperatureAlert,Open-DrainOutput(Event)TheMCP9844temperatureEventoutputpinisanopen-drainoutput.
Thedeviceoutputsasignalwhentheambienttemperaturegoesbeyondtheuserprogrammedtemperaturelimit.
(SeeSection5.
2.
3"EventOutputConfiguration".
)3.
6PowerPin(VDD)VDDisthepowerpin.
Theoperatingvoltagerange,asspecifiedintheDCelectricalspecificationtable,isappliedonthispin.
3.
7ExposedThermalPad(EP)ThereisaninternalelectricalconnectionbetweentheExposedThermalPad(EP)andtheGNDpin;theycanbeconnectedtothesamepotentialonthePrintedCircuitBoard(PCB).
ThisprovidesbetterthermalconductionfromthePCBtothedie.
MCP9844SymbolDescriptionTDFN1A0SlaveAddress2A1SlaveAddress3A2SlaveAddress4GNDGround5SDASerialDataLine6SCLSerialClockLine7EventTemperatureAlertOutput8VDDPowerPin9EPExposedThermalPad(EP);canbeconnectedtoGND.
TABLE3-2:MCP9844ADDRESSBYTEDeviceAddressCodeSlaveAddressA6A5A4A3A2A1A0Sensor0011X1X1X1Note1:User-selectableaddressisshownbyX,whereXis'1'or'0'forVDDandGND,respectivelyMCP9844DS20005192B-page82013MicrochipTechnologyInc.
4.
0SERIALCOMMUNICATION4.
12-WireStandardModeI2CProtocol-CompatibleInterfaceTheMCP9844serialclockinput(SCL)andthebidirectionalserialdataline(SDA)forma2-wirebidirectionalStandardmodeI2Ccompatiblecommunicationport(refertotheInput/OutputPinDCCharacteristicstableandtheSerialInterfaceTimingSpecificationstable).
ThefollowingMCP9844busprotocolisdefinedinTable4-1.
TABLE4-1:MCP9844SERIALBUSPROTOCOLDESCRIPTIONS4.
1.
1DATATRANSFERDatatransfersareinitiatedbyaStartcondition(START),followedbya7-bitdeviceaddressandaread/writebit.
AnAcknowledge(ACK)fromtheslaveconfirmsthereceptionofeachbyte.
EachaccessmustbeterminatedbyaStopcondition(STOP).
RepeatedcommunicationisinitiatedaftertB-FREE.
Thisdevicedoesnotsupportsequentialregisterread/write.
EachregisterneedstobeaddressedusingtheRegisterPointer.
ThisdevicesupportstheReceiveProtocol.
Theregistercanbespecifiedusingthepointerfortheinitialread.
EachrepeatedreadorreceivebeginswithaStartconditionandaddressbyte.
TheMCP9844retainsthepreviouslyselectedregister.
Therefore,theyoutputdatafromthepreviouslyspecifiedregister(repeatedpointerspecificationisnotnecessary).
4.
1.
2MASTER/SLAVEThebusiscontrolledbyamasterdevice(typicallyamicrocontroller)thatcontrolsthebusaccessandgeneratestheStartandStopconditions.
TheMCP9844isaslavedeviceanddoesnotcontrolotherdevicesinthebus.
Bothmasterandslavedevicescanoperateaseithertransmitterorreceiver.
However,themasterdevicedetermineswhichmodeisactivated.
4.
1.
3START/STOPCONDITIONAhigh-to-lowtransitionoftheSDAline(whileSCLishigh)istheStartcondition.
AlldatatransfersmustbeprecededbyaStartconditionfromthemaster.
Alow-to-hightransitionoftheSDAline(whileSCLishigh)signifiesaStopcondition.
IfaStartorStopconditionisintroducedduringdatatransmission,theMCP9844releasesthebus.
AlldatatransfersareendedbyaStopconditionfromthemaster.
4.
1.
4ADDRESSBYTEFollowingtheStartcondition,thehostmusttransmitan8-bitaddressbytetotheMCP9844.
TheaddressfortheMCP9844temperaturesensoris'0011,A2,A1,A0'inbinary,wheretheA2,A1andA0bitsaresetexternallybyconnectingthecorrespondingpinstoVDD'1'orGND'0'.
The7-bitaddresstransmittedintheserialbitstreammustmatchtheselectedaddressfortheMCP9844torespondwithanACK.
Bit8intheaddressbyteisaread/writebit.
Settingthisbitto'1'commandsareadoperation,while'0'commandsawriteoperation(seeFigure4-1).
FIGURE4-1:DeviceAddressing.
TermDescriptionMasterThedevicethatcontrolstheserialbus,typicallyamicrocontroller.
SlaveThedeviceaddressedbythemaster,suchastheMCP9844.
TransmitterDevicesendingdatatothebus.
ReceiverDevicereceivingdatafromthebus.
STARTAuniquesignalfromthemastertoinitiateserialinterfacewithaslave.
STOPAuniquesignalfromthemastertoterminateserialinterfacefromaslave.
Read/WriteAreadorwritetotheMCP9844registers.
ACKAreceiverAcknowledges(ACK)thereceptionofeachbytebypollingthebus.
NAKAreceiverNot-Acknowledges(NAK)orreleasesthebustoshowEnd-of-Data(EOD).
BusyCommunicationisnotpossiblebecausethebusisinuse.
NotBusyThebusisintheIdlestate,bothSDAandSCLremainhigh.
DataValidSDAmustremainstablebeforeSCLbecomeshighinorderforadatabittobeconsideredvalid.
Duringnormaldatatransfers,SDAonlychangesstatewhileSCLislow.
123456789SCLSDA0011A2A1A0StartAddressByteSlaveAddressR/WMCP9844ResponseCodeAddressACK2013MicrochipTechnologyInc.
DS20005192B-page9MCP98444.
1.
5DATAVALIDAftertheStartcondition,eachbitofdatainthetransmissionneedstobesettledforatimespecifiedbytSU-DATAbeforeSCLtogglesfromlow-to-high(seeSerialInterfaceTimingSpecificationstable).
4.
1.
6ACKNOWLEDGE(ACK/NAK)Eachreceivingdevice,whenaddressed,isobligedtogenerateanACKbitafterthereceptionofeachbyte.
ThemasterdevicemustgenerateanextraclockpulseforACKtoberecognized.
TheacknowledgingdevicepullsdowntheSDAlinefortSU-DATAbeforethelow-to-hightransitionofSCLfromthemaster.
SDAalsoneedstoremainpulleddownfortH-DATAafterahigh-to-lowtransitionofSCL.
Duringread,themastermustsignalanEnd-of-Data(EOD)totheslavebynotgeneratinganACKbit(NAK)oncethelastbithasbeenclockedoutoftheslave.
Inthiscase,theslavewillleavethedatalinereleasedtoenablethemastertogeneratetheStopcondition.
4.
1.
7TIMEOUT(TOUT)IftheSCLstaysloworhighfortimespecifiedbytOUT,theMCP9844resetstheserialinterface.
Thisdictatestheminimumclockspeedasspecifiedinthespecification.
MCP9844DS20005192B-page102013MicrochipTechnologyInc.
5.
0FUNCTIONALDESCRIPTIONTheMCP9844temperaturesensorsconsistofabandgaptypetemperaturesensor,aDelta-SigmaAnalog-to-DigitalConverter(ADC),user-programmableregistersanda2-wireI2Cprotocolcompatibleserialinterface.
Figure5-1showsablockdiagramoftheregisterstructure.
FIGURE5-1:FunctionalBlockDiagram.
ClearEvent0.
5°C/bit0.
25°C/bit0.
125°C/bit0.
0625°C/bitTemperatureTUPPERTLOWERConfigurationADCBandGapTemperatureSensorEventStatusOutputControlCriticalEventonlyEventPolarityEventComp.
/Int.
TCRITCapabilityTemp.
RangeAccuracyOutputFeatureRegisterPointerCriticalTripLockAlarmWin.
LockBitShutdownHysteresisManufacturerIDResolutionDeviceID/Rev.
SelectedResolutionStandardI2CInterfaceA0A1A2EventSDASCLVDDGNDI2CBusTime-outShutdownStatusMCP9844TemperatureSensor2013MicrochipTechnologyInc.
DS20005192B-page11MCP98445.
1RegistersTheMCP9844devicehasseveralregistersthatareuseraccessible.
TheseregistersincludetheCapabilityregister,Configurationregister,EventTemperatureUpper-BoundaryandLower-BoundaryTripregisters,CriticalTemperatureTripregister,Temperatureregister,ManufacturerIdentificationregisterandDeviceIdentificationregister.
TheTemperatureregisterisread-onlyandisusedtoaccesstheambienttemperaturedata.
ThedataisloadedinparalleltothisregisteraftertCONV.
TheEventTemperatureUpper-BoundaryandLower-BoundaryTripregistersareread/writes.
Iftheambienttemperaturedriftsbeyondtheuser-specifiedlimits,theMCP9844deviceoutputsasignalusingtheEventpin(refertoSection5.
2.
3"EventOutputConfiguration").
Inaddition,theCriticalTemperatureTripregisterisusedtoprovideanadditionalcriticaltemperaturelimit.
TheCapabilityregisterisusedtoprovidebitsdescribingtheMCP9844'scapabilityinmeasurementresolution,measurementrangeanddeviceaccuracy.
ThedeviceConfigurationregisterprovidesaccesstoconfiguretheMCP9844'svariousfeatures.
Theseregistersaredescribedinfurtherdetailinthefollowingsections.
TheregistersareaccessedbysendingaRegisterPointertotheMCP9844usingtheserialinterface.
Thisisan8-bitwrite-onlypointer.
Register5-1describesthepointerortheaddressofeachregister.
ThisdevicewillnotacknowledgecommandstoregisterpointersotherthanthoselistedinRegister5-1.
REGISTER5-1:REGISTERPOINTER(WRITEONLY)W-0W-0W-0W-0W-0W-0W-0W-0————PointerBitsbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit7-4WritableBits:Write'0'bit3-0PointerBits:0000=Capabilityregister0001=Configurationregister(CONFIG)0010=EventTemperatureUpper-BoundaryTripregister(TUPPER)0011=EventTemperatureLower-BoundaryTripregister(TLOWER)0100=CriticalTemperatureTripregister(TCRIT)0101=Temperatureregister(TA)0110=ManufacturerIDregister0111=DeviceID/Revisionregister1000=Reserved1001=Resolutionregister1XXX=Unused(Thedevicewillnotacknowledgecommandstootherpointerlocations.
)MCP9844DS20005192B-page122013MicrochipTechnologyInc.
TABLE5-1:BITASSIGNMENTSUMMARYFORALLTEMPERATURESENSORREGISTERS(SEESECTION5.
3)RegisterPointer(Hex)MSB/LSBBitAssignment765432100x00MSB00000000LSBSHDNStatustOUTRange1ResolutionRangeAccuracyEvent0x01MSB00000HysteresisSHDNLSBCrt.
Loc.
Win.
Loc.
Int.
Clr.
Evt.
Stat.
Evt.
Cnt.
Evt.
Sel.
Evt.
Pol.
Evt.
Mod.
0x02MSB000SIGN27°C26°C25°C24°CLSB23°C22°C21°C20°C2-1°C2-2°C000x03MSB000SIGN27°C26°C25°C24°CLSB23°C22°C21°C20°C2-1°C2-2°C000x04MSB000SIGN27°C26°C25°C24°CLSB23°C22°C21°C20°C2-1°C2-2°C000x05MSBTATCRITTATUPPERTATLOWERSIGN27°C26°C25°C24°CLSB23°C22°C21°C20°C2-1°C2-2°C2-3°C2-4°C0x06MSB00000000LSB010101000x07MSB00000110LSB000000010x08MSB00000110LSB000000010x09MSB00000000LSB000000Resolution2013MicrochipTechnologyInc.
DS20005192B-page13MCP98445.
1.
1CAPABILITYREGISTERThisisaread-onlyregisterusedtoidentifythetemperaturesensorcapability.
Forexample,theMCP9844deviceiscapableofprovidingtemperatureat0.
25°Cresolution,measuringtemperaturebelowandabove0°C,providing±1°Cand±2°Caccuracyovertheactiveandmonitortemperatureranges(respectively)andprovidinguser-programmabletemperatureeventboundarytriplimits.
Register5-2describestheCapabilityregister.
Thesefunctionsaredescribedinfurtherdetailinthefollowingsections.
REGISTER5-2:CAPABILITYREGISTER(READ-ONLY)ADDRESS'00000000'bU-0U-0U-0U-0U-0U-0U-0U-0bit15bit8R-1R-1R-1R-0R-1R-1R-1R-1SHDNStatustOUTRange—ResolutionMeas.
RangeAccuracyTemp.
Alarmbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15-8Unimplemented:Readas'0'bit7EventOutputStatusDuringShutdown(SHDNStatus):0=Eventoutputremainsinpreviousstate.
Iftheoutputassertsbeforeshutdowncommand,itremainsassertedduringshutdown.
1=Eventoutputdeassertsduringshutdown.
Aftershutdown,ittakestCONVtoreasserttheeventoutput(power-updefault)bit6I2CBusTime-Out(tOUTRange):0=Bustime-outrangeis10msto60ms1=Bustime-outrangeis25msto35ms(power-updefault)bit5Unimplemented:Readas'1'bit4-3Resolution:00=0.
5°C01=0.
25°C(power-updefault)10=0.
125°C11=0.
0625°CThesebitsreflecttheselectedresolution(seeSection5.
2.
4"TemperatureResolution")bit2TemperatureMeasurementRange(Meas.
Range):0=TA0(decimal)fortemperaturebelow0°C1=Thepartcanmeasuretemperaturebelow0°C(power-updefault)MCP9844DS20005192B-page142013MicrochipTechnologyInc.
FIGURE5-2:TimingDiagramforReadingtheCapabilityRegister(SeeSection4.
0"SerialCommunication").
bit1Accuracy:0=Accuracy±2°Cfrom+75°Cto+95°C(ActiveRange)and±3°Cfrom+40°Cto+125°C(MonitorRange)1=Accuracy±1°Cfrom+75°Cto+95°C(ActiveRange)and±2°Cfrom+40°Cto+125°C(MonitorRange)bit0TemperatureAlarm:0=Nodefinedfunction(Thisbitwillneverbeclearedorsetto'0')1=Theparthastemperatureboundarytriplimits(TUPPER/TLOWER/TCRITregisters)andatemperatureeventoutput(JC42.
4requiredfeature)REGISTER5-2:CAPABILITYREGISTER(READ-ONLY)ADDRESS'00000000'b(CONTINUED)SDAACK0011ACapabilityPointer0000ACKS2A1A01234567812345678SCL0AddressByteACK0011AMSBDataACKNAKSP2A1A0123456781234567812345678AddressByteLSBDataRMCP9844MCP9844MCP9844MasterMasterWSDASCL00000000000000011112013MicrochipTechnologyInc.
DS20005192B-page15MCP98445.
1.
2SENSORCONFIGURATIONREGISTER(CONFIG)TheMCP9844devicehasa16-bitConfigurationregister(CONFIG)thatallowstheusertosetvariousfunctionsforarobusttemperaturemonitoringsystem.
Bits10through0areusedtoselecttheeventoutputboundaryhysteresis,deviceShutdownorLow-Powermode,temperatureboundaryandcriticaltemperaturelock,andtemperatureeventoutputenable/disable.
Inaddition,theusercanselecttheeventoutputcondition(outputsetforTUPPERandTLOWERtemperatureboundaryorTCRITonly),readeventoutputstatusandseteventoutputpolarityandmode(ComparatorOutputorInterruptOutputmode).
Thetemperaturehysteresisbits10and9canbeusedtopreventoutputchatterwhentheambienttemperaturegraduallychangesbeyondtheuserspecifiedtemperatureboundary(seeSection5.
2.
2"TemperatureHysteresis(THYST)").
TheContinuousConversionorShutdownmodeisselectedusingbit8.
InShutdownmode,thebandgaptemperaturesensorcircuitstopsconvertingtemperatureandtheAmbientTemperatureregister(TA)holdstheprevioussuccessfullyconvertedtemperaturedata(seeSection5.
2.
1"ShutdownMode").
Bits7and6areusedtolocktheuser-specifiedboundariesTUPPER,TLOWERandTCRITtopreventanaccidentalrewrite.
Bits5through0areusedtoconfigurethetemperatureEventoutputpin.
AllfunctionsaredescribedinRegister5-3(seeSection5.
2.
3"EventOutputConfiguration").
REGISTER5-3:CONFIGURATIONREGISTER(CONFIG)ADDRESS'00000001'bU-0U-0U-0U-0U-0R/W-0R/W-0R/W-0THYSTSHDNbit15bit8R/W-0R/W-0R/W-0R-0R/W-0R/W-0R/W-0R/W-0Crit.
LockWin.
LockInt.
ClearEventStat.
EventCnt.
EventSel.
EventPol.
EventMod.
bit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15-11Unimplemented:Readas'0'bit10-9TUPPERandTLOWERLimitHysteresis(THYST):00=0°C(power-updefault)01=1.
5°C10=3.
0°C11=6.
0°C(RefertoSection5.
2.
3"EventOutputConfiguration")Thisbitcannotbealteredwheneitherofthelockbitsareset(bit6andbit7).
ThisbitcanbeprogrammedinShutdownmode.
bit8ShutdownMode(SHDN):0=ContinuousConversion(power-updefault)1=Shutdown(Low-Powermode)Inshutdown,allpower-consumingactivitiesaredisabled,thoughallregisterscanbewrittentoorread.
Eventoutputwilldeassert.
Thisbitcannotbeset'1'wheneitherofthelockbitsisset(bit6andbit7).
However,itcanbecleared'0'forContinuousConversionwhilelocked(RefertoSection5.
2.
1"ShutdownMode").
MCP9844DS20005192B-page162013MicrochipTechnologyInc.
bit7TCRITLockBit(Crit.
Lock):0=Unlocked.
TCRITregistercanbewritten.
(power-updefault)1=Locked.
TCRITregistercannotbewrittenWhenenabled,thisbitremainsset'1'orlockeduntilclearedbyinternalreset(Section5.
3"SummaryofPower-onDefault").
Thisbitdoesnotrequireadouble-write.
ThisbitcanbeprogrammedinShutdownmode.
bit6TUPPERandTLOWERWindowLockBit(Win.
Lock):0=Unlocked.
TUPPERandTLOWERregisterscanbewritten.
(power-updefault)1=Locked.
TUPPERandTLOWERregisterscannotbewrittenWhenenabled,thisbitremainsset'1'orlockeduntilclearedbypower-onRespell(Section5.
3"Sum-maryofPower-onDefault").
Thisbitdoesnotrequireadouble-write.
ThisbitcanbeprogrammedinShutdownmode.
bit5InterruptClear(Int.
Clear)Bit:0=Noeffect(power-updefault)1=Clearinterruptoutput.
Whenreadthisbitreturns'0'ThisbitclearstheInterruptflagwhichdeassertseventoutput.
InShutdownmode,theeventoutputisalwaysdeasserted.
Therefore,settingthisbitinShutdownmodeclearstheinterruptafterthedevicereturnstonormaloperation.
bit4EventOutputStatus(EventStat.
)Bit:0=Eventoutputisnotassertedbythedevice(power-updefault)1=Eventoutputisassertedasacomparator/InterruptorcriticaltemperatureoutputInShutdownmodethisbitwillclearbecauseeventoutputisalwaysdeassertedinShutdownmode.
bit3EventOutputControl(EventCnt.
)Bit:0=EventoutputDisabled(power-updefault)1=EventoutputEnabledThisbitcannotbealteredwheneitherofthelockbitsisset(bit6andbit7).
ThisbitcanbeprogrammedinShutdownmode,buteventoutputwillremaindeasserted.
bit2EventOutputSelect(EventSel.
)Bit:0=EventoutputforTUPPER,TLOWERandTCRIT(power-updefault)1=TA≥TCRITonly.
(TUPPERandTLOWERtemperatureboundariesaredisabled.
)WhentheAlarmWindowLockbitisset,thisbitcannotbealtereduntilunlocked(bit6).
ThisbitcanbeprogrammedinShutdownmode,buteventoutputwillremaindeasserted.
bit1EventOutputPolarity(EventPol.
)Bit:0=Active-low(power-updefault.
Pull-upresistorrequired)1=Active-highThisbitcannotbealteredwheneitherofthelockbitsisset(bit6andbit7).
ThisbitcanbeprogrammedinShutdownmode,buteventoutputwillremaindeasserted,seeSection5.
2.
3"EventOutputConfiguration"bit0EventOutputMode(EventMod.
)Bit:0=Comparatoroutput(power-updefault)1=InterruptoutputThisbitcannotbealteredwheneitherofthelockbitsisset(bit6andbit7).
ThisbitcanbeprogrammedinShutdownmode,buteventoutputwillremaindeasserted.
REGISTER5-3:CONFIGURATIONREGISTER(CONFIG)ADDRESS'00000001'b2013MicrochipTechnologyInc.
DS20005192B-page17MCP9844FIGURE5-3:TimingDiagramforWritingtotheConfigurationRegister(SeeSection4.
0"SerialCommunication".
WritingtotheCONFIGRegistertoEnabletheEventOutputpinb.
SDAACK0011A0000ACKS2A1A01234567812345678SCL0AddressByteWMCP9844MCP9844MSBDataACKACKP1234567812345678LSBDataConfigurationPointerMCP9844MCP98440010000000000001000Note:thisisanexampleroutine:i2c_start();//sendSTARTcommandi2c_write(AddressByte&0xFE);//WRITECommand//also,makesurebit0iscleared'0'i2c_write(0x01);//WriteCONFIGRegisteri2c_write(0x00);//Writedatai2c_write(0x08);//Writedatai2c_stop();//sendSTOPcommandMCP9844DS20005192B-page182013MicrochipTechnologyInc.
FIGURE5-4:TimingDiagramforReadingfromtheConfigurationRegister(SeeSection4.
0"SerialCommunication").
SDAACK0011AConfigurationPointer0000ACKS2A1A01234567812345678SCL0AddressByteACK0011AMSBDataACKNAKSP2A1A0123456781234567812345678AddressByteLSBDataRMCP9844MCP9844MCP9844MasterMasterWSDASCL0010000000000001000ReadingtheCONFIGRegister.
Note:ItisnotnecessarytoselecttheRegisterPointerifitwassetfromthepreviousread/write.
Note:thisisanexampleroutine:i2c_start();//sendSTARTcommandi2c_write(AddressByte&0xFE);//WRITECommand//also,makesurebit0iscleared'0'i2c_write(0x01);//WriteCONFIGRegisteri2c_start();//sendRepeatSTARTcommandi2c_write(AddressByte|0x01);//READCommand//also,makesurebit0isset'1'UpperByte=i2c_read(ACK);//READ8bits//andSendACKbitLowerByte=i2c_read(NAK);//READ8bits//andSendNAKbiti2c_stop();//sendSTOPcommand2013MicrochipTechnologyInc.
DS20005192B-page19MCP98445.
1.
3UPPER/LOWER/CRITICALTEMPERATURELIMITREGISTERS(TUPPER/TLOWER/TCRIT)TheMCP9844devicehasa16-bitread/writeEventOutputTemperatureUpper-BoundaryTripregister(TUPPER),a16-bitLower-BoundaryTripregister(TLOWER)anda16-bitCriticalBoundaryTripregister(TCRIT)thatcontains11-bitdataintwo'scomplementformat(0.
25°C).
Thisdatarepresentsthemaximumandminimumtemperatureboundaryortemperaturewindowthatcanbeusedtomonitorambienttemperature.
Ifthisfeatureisenabled(Section5.
1.
2"SensorConfigurationRegister(CONFIG)")andtheambienttemperatureexceedsthespecifiedboundaryorwindow,theMCP9844assertsaneventoutput.
(RefertoSection5.
2.
3"EventOutputConfiguration").
REGISTER5-4:UPPER/LOWER/CRITICALTEMPERATURELIMITREGISTER(TUPPER/TLOWER/TCRIT)ADDRESS'00000010'b/'00000011'b/'00000100'b(Note1)U-0U-0U-0R/W-0R/W-0R/W-0R/W-0R/W-0———Sign27°C26°C25°C24°Cbit15bit8R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0U-0U-023°C22°C21°C20°C2-1°C2-2°C——bit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15-13Unimplemented:Readas'0'bit12Sign:0=TA0°C1=TA0°Cbit11-2TUPPER/TLOWER/TCRIT:Temperatureboundarytripdataintwo'scomplementformat.
bit1-0Unimplemented:Readas'0'Note1:Thistableshowstwo16-bitregistersforTUPPER,TLOWERandTCRITlocatedat'00000010b','00000011b'and'00000100b',respectively.
MCP9844DS20005192B-page202013MicrochipTechnologyInc.
FIGURE5-5:TimingDiagramforWritingandReadingfromtheTUPPERRegister(SeeSection4.
0"SerialCommunication").
SDAACK0011ATUPPERPointer0000ACKS2A1A01234567812345678SCL0AddressByteACK0011AMSBDataACKNAKSP2A1A0123456781234567812345678AddressByteLSBDataRMCP9844MCP9844MCP9844MasterMasterWSDASCL0100000010110100000ReadingfromtheTUPPERRegister.
Writing90°CtotheTUPPERRegisterb.
SDAACK0011A0000ACKS2A1A01234567812345678SCL0AddressByteWMCP9844MCP9844MSBDataACKACKP1234567812345678LSBDataTUPPERPointerMCP9844MCP98440100000010110100000Note:ItisnotnecessarytoselecttheRegisterPointerifitwassetfromthepreviousread/write.
2013MicrochipTechnologyInc.
DS20005192B-page21MCP98445.
1.
4AMBIENTTEMPERATUREREGISTER(TA)TheMCP9844deviceusesabandgaptemperaturesensorcircuittooutputanalogvoltageproportionaltoabsolutetemperature.
AninternalADCisusedtoconverttheanalogvoltagetoadigitalword.
Thecon-verterresolutionissetto0.
25°C+sign(11-bitdata).
Thedigitalwordisloadedtoa16-bitread-onlyAmbientTemperatureregister(TA)thatcontains11-bittemperaturedataintwo'scomplementformat.
TheTAregisterbits(bits12through0)aredouble-buff-ered.
Therefore,theusercanaccesstheregisterwhile,inthebackground,theMCP9844performsanAnalog-to-Digitalconversion.
ThetemperaturedatafromtheADCisloadedinparalleltotheTAregisterattCONVrefreshrate.
Inaddition,theTAregisterusesthreebits(bits15,14and13)toreflecttheEventpinstate.
Thisallowstheusertoidentifythecauseoftheeventoutputtrigger(seeSection5.
2.
3"EventOutputConfiguration");bit15issetto'1'ifTAisgreaterthanorequaltoTCRIT,bit14issetto'1'ifTAisgreaterthanTUPPERandbit13issetto'1'ifTAislessthanTLOWER.
TheTAregisterbitassignmentandboundaryconditionsaredescribedinRegister5-5.
REGISTER5-5:AMBIENTTEMPERATUREREGISTER(TA)ADDRESS'00000101'b(Note1)R-0R-0R-0R-0R-0R-0R-0R-0TAvs.
TCRITTAvs.
TUPPERTAvs.
TLOWERSIGN27°C26°C25°C24°Cbit15bit8R-0R-0R-0R-0R-0R-0R-0R-023°C22°C21°C20°C2-1°C2-2°C2-3°C2-4°Cbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15TAvs.
TCRIT(1)Bit:0=TATCRIT1=TATCRITbit14TAvs.
TUPPER(1)Bit:0=TATUPPER1=TATUPPERbit13TAvs.
TLOWER(1)Bit:0=TATLOWER1=TATLOWERbit12SIGNBit:0=TA0°C1=TA0°Cbit11-0AmbientTemperature(TA)Bits:(Note2)12-bitAmbientTemperaturedataintwo'scomplementformat.
Note1:Bits15,14and13arenotaffectedbythestatusoftheeventoutputconfiguration(bits5to0ofCONFIG)(Register5-3).
2:Bits2,1,and0mayremainclear'0'dependingonthestatusoftheresolutionregister.
Thepower-updefaultis0.
25°C/bit,bits1and0remainclear'0'.
MCP9844DS20005192B-page222013MicrochipTechnologyInc.
5.
1.
4.
1TAbitstoTemperatureConversionToconverttheTAbitstodecimaltemperature,theupperthreeboundarybits15,14and13)mustbemaskedout.
Thendeterminethesignbit(bit12)tocheckpositiveornegativetemperature,shiftthebitsaccordinglyandcombinetheupperandlowerbytesofthe16-bitregister.
Theupperbytecontainsdatafortemperaturesgreaterthan32°Cwhilethelowerbytecontainsdatafortemperaturelessthan32°C,includingfractionaldata.
Whencombiningtheupperandlowerbytes,theupperbytemustberight-shiftedby4bits(ormultiplyby24),andthelowerbytemustbeleft-shiftedby4bits(ormultiplyby2-4).
Addingtheresultsoftheshiftedvaluesprovidesthetemperaturedataindecimalformat,seeEquation5-1.
Thetemperaturebitsareintwo'scomplimentformat;therefore,positivetemperaturedataandnegativetem-peraturedataarecomputeddifferently.
Equation5-1showsthetemperaturecomputation.
TheexampleinstructioncodeoutlinedinFigure5-6showsthecommunicationflow.
Additionally,refertoFigure5-7forthetimingdiagram.
EQUATION5-1:BYTESTOTEMPERATURECONVERSIONFIGURE5-6:ExampleInstructionCode.
Where:TA=AmbientTemperature(°C)UpperByte=TAbit15tobit8LowerByte=TAbit7tobit0Temperature0°CTemperature0°CTAUpperByte24LowerByte24–+=TAUpperByte24LowerByte24–+256–=i2c_start();//sendSTARTcommandi2c_write(AddressByte&0xFE);//WRITECommand//also,makesurebit0iscleared'0'i2c_write(0x05);//WriteTARegisterAddressi2c_start();//RepeatSTARTi2c_write(AddressByte|0x01);//READCommand//also,makesurebit0isSet'1'UpperByte=i2c_read(ACK);//READ8bits//andSendACKbitLowerByte=i2c_read(NAK);//READ8bits//andSendNAKbiti2c_stop();//sendSTOPcommand//Convertthetemperaturedata//FirstCheckflagbitsif((UpperByte&0x80)==0x80){//TATCRIT}if((UpperByte&0x40)==0x40){//TATUPPER}if((UpperByte&0x20)==0x20){//TATLOWER}UpperByte=UpperByte&0x1F;//Clearflagbitsif((UpperByte&0x10)==0x10){//TA0°CUpperByte=UpperByte&0x0F;//ClearSIGNTemperature=(UpperBytex16+LowerByte/16)-256;}else//TA0°CTemperature=(UpperBytex16+LowerByte/16);//Temperature=AmbientTemperature(°C)ThisexampleroutineassumesthevariablesandI2Ccommunicationsubroutinesarepredefined:2013MicrochipTechnologyInc.
DS20005192B-page23MCP9844FIGURE5-7:TimingDiagramforReading+25.
25°CTemperaturefromtheTARegister(SeeSection4.
0"SerialCommunication").
SDAACK0011ATAPointer0000ACKS2A1A01234567812345678SCL0AddressByteACK0011AMSBDataACKNAKSP2A1A0123456781234567812345678AddressByteLSBDataRMCP9844MCP9844MCP9844MasterMasterWSDASCL1010000000110010100Note:ItisnotnecessarytoselecttheRegisterPointerifitwassetfromthepreviousread/write.
MCP9844DS20005192B-page242013MicrochipTechnologyInc.
5.
1.
5MANUFACTURERIDREGISTERThisregisterisusedtoidentifythemanufacturerofthedeviceinordertoperformmanufacturerspecificoperations.
TheManufacturerIDfortheMCP9844is0x0054(hexadecimal).
FIGURE5-8:TimingDiagramforReadingtheManufacturerIDRegister(SeeSection4.
0"SerialCommunication").
REGISTER5-6:MANUFACTURERIDREGISTER(READ-ONLY)ADDRESS'00000110'bR-0R-0R-0R-0R-0R-0R-0R-0ManufacturerIDbit15bit8R-0R-1R-0R-1R-0R-1R-0R-0ManufacturerIDbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15-0DeviceManufacturerIdentificationNumber.
SDAACK0011AManuf.
IDPointer0000ACKS2A1A01234567812345678SCL0AddressByteACK0011AMSBDataACKNAKSP2A1A0123456781234567812345678AddressByteLSBDataRMCP9844MCP9844MCP9844MasterMasterWSDASCL1100000000001010100Note:ItisnotnecessarytoselecttheRegisterPointerifitwassetfromthepreviousread/write.
2013MicrochipTechnologyInc.
DS20005192B-page25MCP98445.
1.
6DEVICEIDANDREVISIONREGISTERTheDeviceIDandRevisionregisterlocatedatAddressPointer0x08isusedtoidentifyMicrochipdevices.
Theupperbyteoftheseregistersisusedtospecifythedeviceidentificationandthelowerbyteisusedtospecifydevicesiliconrevision.
ThedeviceIDfortheMCP9844is0x06(hex).
Therevision(LowerByte)beginswith0x00(hex)forthefirstrelease,withthenumberbeingincrementedasrevisedversionsarereleased.
REGISTER5-7:TSE2004AVDEVICEIDANDDEVICEREVISION(READ-ONLY)ADDRESS'00000111'bAND'00001000'bR-0R-0R-0R-0R-0R-1R-1R-0DeviceIDbit15bit8R-0R-0R-0R-0R-0R-0R-0R-1DeviceRevisionbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15-8DeviceID:Bit15tobit8areusedfordeviceIDbit7-0DeviceRevision:Bit7tobit0areusedfordevicerevisionMCP9844DS20005192B-page262013MicrochipTechnologyInc.
5.
1.
7RESOLUTIONREGISTERThisregisterallowstheusertochangethesensorresolution(seeSection5.
2.
4"TemperatureResolution").
ThePORdefaultresolutionis0.
25°C.
TheselectedresolutionisalsoreflectedintheCapabilityregister(seeRegister5-2).
Note:InordertopreventaccidentallywritingtheresolutionregistertoahigherresolutionandexceedingthemaximumtemperatureconversiontimeoftCONV=125ms,aShut-downcommand(usingtheCONFIGregis-ter)isrequiredtochangetheresolutionregister.
ThedevicemustbeinShutdownmodetochangetheresolution.
REGISTER5-8:RESOLUTIONREGISTER'00001001'bR/W-0U-0U-0U-0U-0U-0U-0U-0—bit15bit8U-0U-0U-0U-0U-0U-0R/W-0R/W-1Resolutionbit7bit0Legend:R=ReadablebitW=WritablebitU=Unimplementedbit,readas'0'-n=ValueatPOR'1'=Bitisset'0'=Bitisclearedx=Bitisunknownbit15Unimplemented:Readas'0'bit14-2Unimplemented:Readas'0'bit1-0Resolution:00=LSb=0.
5°C(tCONV=30ms,typical)01=LSb=0.
25°C(power-updefault,tCONV=65ms,typical)10=LSb=0.
125°C(tCONV=130ms,typical)11=LSb=0.
0625°C(tCONV=260ms,typical)2013MicrochipTechnologyInc.
DS20005192B-page27MCP98445.
2SENSORFEATUREDESCRIPTION5.
2.
1SHUTDOWNMODEShutdownmodedisablesallpower-consumingactivities(includingtemperaturesamplingoperations)whileleavingtheserialinterfaceactive.
Thismodeisselectedbysettingbit8ofCONFIGto'1'.
Inthismode,thedeviceconsumesISHDN.
Itremainsinthismodeuntilbit8iscleared'0'toenableContinuousConversionmode,oruntilpowerisrecycled.
TheShutdownbit(bit8)cannotbesetto'1'whilebits6and7ofCONFIG(Lockbits)aresetto'1'.
However,itcanbecleared'0'orreturnedtoContinuousConversionwhilelocked.
InShutdownmode,allregisterscanbereadorwritten.
However,theserialbusactivityincreasestheshutdowncurrent.
IfthedeviceisshutdownwhiletheEventpinisasserted,thentheeventoutputwillbedeassertedduringshutdown.
Itwillremaindeasserteduntilthedeviceisenabledfornormaloperation.
Oncethedeviceisenabled,ittakestCONVbeforethedevicereassertstheeventoutput.
5.
2.
2TEMPERATUREHYSTERESIS(THYST)Ahysteresisof0°C,1.
5°C,3°Cor6°CcanbeselectedfortheTUPPER,TLOWERandTCRITtemperateboundariesusingbits10and9ofCONFIG.
Thehysteresisappliesfordecreasingtemperatureonly(hottocold),orastemperaturedriftsbelowthespecifiedlimit.
Thehysteresisbitscannotbechangedifeitherofthelockbits,bits6and7ofCONFIG,aresetto'1'.
TheTUPPER,TLOWERandTCRITboundaryconditionsaredescribedgraphicallyinFigure5-9.
5.
2.
3EVENTOUTPUTCONFIGURATIONTheeventoutputcanbeenabledusingbit3ofCONFIG(EventOutputControlbit)andcanbeconfiguredaseitheracomparatoroutputorasInterruptOutputmodeusingbit0ofCONFIG(Eventmode).
Thepolaritycanalsobespecifiedasanactive-highoractive-lowusingbit1ofCONFIG(eventpolarity).
Theeventoutputrequiresapull-upresistortofunction.
Theseconfigurationsaredesignedtoserveprocessorswithlow-to-highorhigh-to-lowedgetriggeredinputs.
Withactive-highconfiguration,whentheeventoutputdeasserts,powerwillbedissipatedacrossthepull-upresistor.
Whentheambienttemperatureincreasesabovethecriticaltemperaturelimit,theeventoutputisforcedtoacomparatoroutput(regardlessofbit0ofCONFIG).
Whenthetemperaturedriftsbelowthecriticaltemperaturelimitminushysteresis,theeventoutputautomaticallyreturnstothestatespecifiedbybit0ofCONFIG.
Thestatusoftheeventoutputcanbereadusingbit4ofCONFIG(Eventstatus).
Thisbitcannotbesetto'1'inShutdownmode.
Bit7and6oftheCONFIGregistercanbeusedtolocktheTUPPER,TLOWERandTCRITregisters.
Thebitspreventfalsetriggersattheeventoutputduetoanaccidentalrewritetotheseregisters.
Theeventoutputcanalsobeusedasacriticaltemperatureoutputusingbit2ofCONFIG(criticaloutputonly).
Whenthisfeatureisselected,theeventoutputbecomesacomparatoroutput.
Inthismode,theinterruptoutputconfiguration(bit0ofCONFIG)isignored.
MCP9844DS20005192B-page282013MicrochipTechnologyInc.
5.
2.
3.
1ComparatorModeComparatormodeisselectedusingbit0ofCONFIG.
Inthismode,theeventoutputisassertedasactive-highoractive-lowusingbit1ofCONFIG.
Figure5-9showstheconditionsthattoggletheeventoutput.
IfthedeviceentersShutdownmodewithassertedeventoutput,theoutputwilldeassert.
ItwillremaindeasserteduntilthedeviceentersContinuousConver-sionmodeandafterthefirsttemperatureconversioniscompleted,tCONV.
Aftertheinitialtemperatureconver-sion,TAmustsatisfytheTUPPERorTLOWERboundaryconditionsinorderforeventoutputtobeasserted.
Comparatormodeisusefulforthermostattypeapplications,suchasturningonacoolingfanortriggeringasystemshutdownwhenthetemperatureexceedsasafeoperatingrange.
5.
2.
3.
2InterruptModeInInterruptmode,theeventoutputisassertedasactive-highoractive-low(dependingonthepolarityconfiguration)whenTAdriftsaboveorbelowTUPPERandTLOWERlimits.
Theoutputisdeassertedbysettingbit5(InterruptClear)ofCONFIG.
IfthedeviceentersShutdownmodewithassertedeventoutput,theoutputwilldeassert.
ItwillremaindeasserteduntilthedeviceentersContinuousConversionmodeandafterthefirsttemperatureconversioniscompleted,tCONV.
Iftheinter-ruptclearbit(bit5)isneverset,thentheeventoutputwillreassertafterthefirsttemperatureconversion.
Inaddition,ifTA>=TCRIT,theeventoutputisforcedasComparatormodeandassertsuntilTA7')1@1RWH)RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDWKWWSZZZPLFURFKLSFRPSDFNDJLQJMCP9844DS20005192B-page362013MicrochipTechnologyInc.
APPENDIXA:REVISIONHISTORYRevisionB(July2014)Thefollowingisthelistofmodifications.
1.
UpdatedtheSerialInterfaceTimingSpecifi-cationssectiontoinclude400kHzoperationfrom1.
7Vto3.
6V.
2.
UpdatedtheTemperatureSensorDCCharac-teristicstable.
3.
Updatedverbiagethroughoutthedocument.
RevisionA(March2013)OriginalReleaseofthisDocument.
2013MicrochipTechnologyInc.
DS20005192B-page37MCP9844PRODUCTIDENTIFICATIONSYSTEMToorderorobtaininformation,e.
g.
,onpricingordelivery,refertothefactoryorthelistedsalesoffice.
Device:MCP9844T:TemperatureSensorTemperatureRange:E=-40°Cto+125°C(Extended)Package:MNY*=PlasticDualFlat,NoLead,(2x3TDFN),8-lead(TDFN)*Y=Nickelpalladiumgoldmanufacturingdesignator.
OnlyavailableontheTDFNpackage.
PARTNO.
/XXPackageTemperatureRangeDeviceExamples:a)MCP9844T-BE/MNY:TapeandReel,Extendedtemp.
,8LD2x3TDFNpkg.
-XMCP9844DS20005192B-page382013MicrochipTechnologyInc.
NOTES:2013-2014MicrochipTechnologyInc.
DS20005192B-page39Informationcontainedinthispublicationregardingdeviceapplicationsandthelikeisprovidedonlyforyourconvenienceandmaybesupersededbyupdates.
Itisyourresponsibilitytoensurethatyourapplicationmeetswithyourspecifications.
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Microchipdisclaimsallliabilityarisingfromthisinformationanditsuse.
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