bq32000 Real-Time Clock (RTC) - TI.com

1 Bq32 to VReal-TimeClockControllerProductFolderSa mple &BuyTechnicalDocumentsTools &SoftwareSupport &Communitybq32000 SLUS900E DECEMBER2008 REVISEDAUGUST2015bq32000 real -TimeClock (RTC)1 Features3 DescriptionThe bq32000deviceis a compatiblereplacementfor1 AutomaticSwitchoverto BackupSupplyindustrystandardreal-timeclo cks. I2C InterfaceSupportsSerialClockup to 400 kHzThebq32000featuresan automaticbackupsupply +126-ppmAdjustmentcanbe implementedusinga capacitoror non- 8-PinSOICP ackageprogrammablecalibrationadjustmentf rom 63 ppmto + bq32000registersincludean OF 40 C to 85 C AmbientOperatingTemperature(oscillatorfa il) flag indicatingthe statusof the RTCoscillator,as well as a STOPbit that allowsthe host2 Applicationsprocessorto disablethe timeregisters GeneralConsumerElectronicsare normallyupdatedonceper second,and all theregistersare updatedat the sametimeto (1)PARTNUMBERPACKAGEBODYSIZE(NOM) bq32000 SOIC(8) x (1)

2 For all availablepackages,see the orderableaddendumatthe end of the IMPORTANTNOTICEat the end of this datasheetaddressesavailability,warranty, changes,use in safety-criticalapplications,intellectual propertymattersand DECEMBER2008 Applicationand Pin Configurationand Deviceand Mechanical,Packaging,and RevisionHistoryNOTE:Pagenumbersfor previousrevisionsmay differfrompagenumbersin the (November2011)to RevisionEPage AddedESDR atingstable,FeatureDescriptionsection,De viceFunctionalModes,Applicationand Implementationsection,PowerSupplyRecomme ndationssection,Layoutsection,Deviceand DocumentationSupportsection,andMechanica l,Packaging,and AddedStorageTemperatureto ChangedVCC= 0 to VCCneedsa 2008 2015, DECEMBER2008 REVISEDAUGUST20155 Pin Configurationand FunctionsD Package8-PinSOICTop ViewPin serialinterfaceclockSDA5I/OI2C 2008 2015,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback3 ProductFolderLinks.

3 Bq32000bq32000 SLUS900E DECEMBER2008 (1)overoperatingfree-airtemperaturerange (unlessotherwisenoted)MINMAXUNITVCCto GND ,VINAll otherpins to GND + ,TJ 40150 CStoragetemperature,Tstg 60150 C(1)Stressesbeyondthoselistedunderabsolu temaximumratingsmay causepermanentdamageto the stressratingsonly,and functionaloperationof the deviceat theseor any otherconditionsbeyondthoseindicatedunder recommendedoperatingconditionsis not absolute-maximum-ratedconditionsfor extendedperiodsmay (HBM),per ANSI/ESDA/JEDECJS-001,all pins(1)2000V(ESD)ElectrostaticdischargeV Chargeddevicemodel(CDM),per JEDEC specificationJESD22-C101,all500pins(2)(1 )JEDEC documentJEP155statesthat 500-VHBM allowssafe manufacturingwith a standardESDcontrolprocess.(2)JEDEC documentJEP157statesthat 250-VCDM allowssafe manufacturingwith a ,VCCto 4085 CLCrystalload (unlessotherwisenoted) bq32000 THERMALMETRIC(1)D (SOIC)UNIT8 PINSR C/WR JC(top)Junction-to-case(top) C/WR C/W C/W JTJunction-to-boardcharacterizationparam eter55 C/W(1)For moreinformationabouttraditionaland new thermalmetrics,see theSemiconductorandICPackageThermalMetri csapplicationreport, 2008 2015, DECEMBER2008 (unlessotherwisenoted)PARAMETERTESTCONDI TIONSMINTYPMAXUNITPOWERSUPPLYICCVCC supplycurrent100 pulse(1), VBACK= 3 V, Oscillatoron, TA= 25 ALOGICLEVELINPUTSVILI nputlow VCCVVIHI nputhigh VCCVIINI nputcurrent0 V VIN VCC-11 ALOGICLEVELOUTPUTSVOLO utputlow voltageIOL= 3 AREAL-TIMECLOCKCHARACTERISTICSPre-calibr ationaccuracyVCC= V, VBACK= 3 V, Oscillatoron, TA= 25 C 35(2)ppm(1)The currentsmeasuredafterissuinga pulseon VCC.

4 The pulseamplitude0-VCC; pulsewidthmin 1 ms.(2)Typicalaccuracyis measuredusingreferenceboarddesignand boarddesignand crystalsectionresultsin TimingRequirementsSTANDARDMODEFASTMODEUN ITMINMAXMINMAX fsclI2C clockfrequency01000400kHztschI2C clockhigh stsclI2C clocklow stspI2C spiketime050050nstsdsI2C serialdatasetuptime250100nstsdhI2C serialdatahold time00nsticrI2C inputrise time100020 + (1)300nsticfI2C inputfall time30020 + (1)300nstocfI2C outputfall time30020 + (1)300 stbufI2C bus free ststsI2C ststhI2C Starthold stspsI2C stvd(data)Validdatatime (SCLlow to SDAvalid)11 stvd(ack)Validdatatime of ACK11 s(ACKsignalfromSCLlow to SDAlow)(1)Cb= total capacitanceof one bus line in pFCopyright 2008 2015,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback5 (uA) ICC (uA) Vbackup (V) Icc (uA)Iback (uA)C001 VCC = 2 V (uA) ICC (uA) Vbackup (V) Icc (uA)Iback (uA)C002 VCC = V VCCSDASCLS tart ConditionSDASCLS tart ConditionStop Condition89tspsticfticrtsdhtvdtvdtbufD7/ Aticfticrtsdstsdststhtschtscl1/fscl1234b q32000 SLUS900E DECEMBER2008 I2C CurrentConsumptionvs BackupSupplyVoltageFigure3.

5 CurrentConsumptionvs BackupSupplyVoltage6 SubmitDocumentationFeedbackCopyright 2008 2015, kWVBACKOSCIOSCOUse onlysuper-capacitoror battery,not FGNDI2C RegisterInterface WithUndervoltageLockout32-kHzOscillatorT rickleChargeAutomaticBackupSwitchVCOREI nterruptGeneratorVCCVCCR egistersPlace supply-decouplingcapacitor near supply pin1 DECEMBER2008 REVISEDAUGUST20157 bq32000is a real -timeclockthat featuresan automaticbackupsupplywith an :All pullupresistorsshouldbe connectedto VCCsuchthat no pullupis FunctionThe IRQ pin of the bq32000functionsas a general-purposeoutputor a frequencytest functionofIRQ is configurablein the deviceregisterspaceby settingthe FT, FTF,and OUTbits. On initialpowercycles,the OUTbit is set to one,and the FTFand FT bits are set to subsequentpower-ups,with backupsupplypresent,the OUTbit remainsunchanged,and the FTF and FT bits are set to ,the IRQ pin functionis pullupresistorshouldbe tied to VCCto preventIRQ operationwhenoperatingon effectof the calibrationlogicis not normallyobservablewhenIRQ isconfiguredto output1 Hz.

6 The calibrationlogicfunctionsby periodicallyadjustingthe widthof the calibrationeffectis observableonly everyeightor sixteenminutes,dependingon the sign of the 2008 2015,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback7 ProductFolderLinks:bq32000bq32000 SLUS900E DECEMBER2008 (continued)Figure4. IRQ Pin FunctionalDiagramTable1. IRQ FunctionFTOUTFTFIRQ STATE1X11 Hz1X0512 Hz01X100X08 SubmitDocumentationFeedbackCopyright 2008 2015, AC KVR E FVCC 5 V/ms (max) AC KVR E FOn VBAC KOn VBAC KOn VC COn VC CVBACK> VREFVBACK> E FVB AC KOn VBAC KOn VC CVREF> E FVB AC KOn VBAC KOn VC CVREF> VBACKV oltageVoltageVoltageVoltageT imeT imeTimeTimeVCCVCCVCC 5 V/ms (max) DECEMBER2008 bq32000has an internalswitchovercircuitthat causesthe deviceto switchfrommainpowersupplytobackuppowersu pplywhenthe voltageof the mainsupplypin VCCdropsbelowa VBACK switchovercircuitusesan internalreferencevoltageVREF derivedfromthe on-chipbandgapreference; V.

7 The deviceswitchesto the VBACK supplywhenVCCis less thanthe lesserof VBACKor ,the deviceswitchesto the VCCsupplywhenVCCis greaterthaneitherVBACKor resetto defaultvalueswhenthe RTCswitchesfrommainpowersupplyto the registerdefinitionsto determinewhatregisterbits are effectedby a backupswitchover(effectedbits havetheirresetvalue(1/0)shownfor 'Cycle',bits that are unchangedby backupare marked'UC').The time keepingregisterscan take up to 1 secondto updateafterthe RTCswitchesfrombackuppowersupplyto SwitchoverDiagramCopyright 2008 2015,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback9 ProductFolderLinks:bq32000940W20 kW180 WVBACKbq32000 SLUS900E DECEMBER2008 tricklechargecircuitto maintainthe chargeof the backupsupplywhena supercapacitoris tricklechargecircuitis implementedas a seriesof threeswitchesthat are independentlycontrolledby settingthe TCHE[3:0],TCH2,and TCFE bits in the [3:0]mustbe writtenas 0x5hand TCH2as 1 to closethe tricklechargeswitchesand enablechargingofthe backupsupplyfromVCC.

8 Additionally,TCFEcan be set to 1 to bypassthe internaldiodeand boostthechargevoltageof the tricklechargeswitchesare openedwhenthe deviceis initiallypoweredon and eachtimethe deviceswitchesfromthe mainsupplyto the tricklechargecircuitisintendedfor use withsupercapacitors;however,it can be usedwitha takennot to overchargea the rechargeablebatteryor deviceswitchesfromthe mainpowersupplyto backupsupply,the TimekeepingregisterRegisters[0-9] cannotbe accessedvia the I2C. The accessto theseregistersare only whenVCC> Timekeepingregisterscan takeup to 1 secondto updateafterthe deviceswitchesfrombackuppowersupplyto SerialInterfaceThe I2C interfaceallowscontroland monitoringof the RTCby a is a two-wireserialinterfacedevelopedby PhilipsSemiconductor(seeI2C-BusSpecifica tion, , January2000).The bus consistsof a dataline (SDA)and a clockline (SCL)with bus is idle,bothSDAand SCLlinesare masterdevice,usuallya microcontrolleror a digitalsignalprocessor,controlsthe generatingthe SCLsignaland masteralso generatesspecificconditionsthat indicatethe STARTand STOPof slavedevicereceivesand/ortransmitsdataon the bus undercontrolof the as a communicationis initiatedby a mastersendinga startcondition,a high-to-lowtransitionon the SDAI/O whileSCLis startcondition,the deviceaddressbyteis sent,most-significantbit (MSB)first,includingthe datadirectionbit (R/W).

9 Afterreceivinga validaddressbyte,this devicerespondswithanacknowledge,a low on the SDAI/O duringthe highof the the I2C slaveaddress11010000bfor writecommandsand slaveaddress11010001bfor devicedoesnot respondto the generalcall 2008 2015,TexasInstrumentsIncorporatedProduct FolderLinks:bq32000S1110000 WSlaveAddressACK(A )NACKSubAddressSTARTSSTART1110000 RSlaveAddressACK(D )NACKDataN(D )N+1 NACKDataN+ DECEMBER2008 REVISEDAUGUST2015 Programming(continued)A databyte followsthe the R/W bit is low, the datais writtenfromthe the R/Wbit is high,the datafromthis deviceare the valuesreadfromthe registerpreviouslyselectedby a writeto databyteis followedby an acknowledgesentfromthis outputonly ifcompletebytesare receivedand stopcondition,whichis a low-to-hightransitionon the SDAI/O whilethe SCLinputis high,is sentby themasterto terminatethe masterdevicemustwait at least60 s afterthe RTCexitsbackupmodetogeneratea I2C ReadModeFigure8.

10 I2C WriteModeCopyright 2008 2015,TexasInstrumentsIncorporatedSubmitD ocumentationFeedback11 ProductFolderLinks:bq32000bq32000 SLUS900E DECEMBER2008 NormalRegistersADDRESSREGISTERREGISTERNA MEDESCRIPTION(HEX)00x00 SECONDSC locksecondsand STOPbit10x01 MINUTESC lockminutes20x02 CENT_HOURSC lockhours,century,and CENT_ENbit30x03 DAYC lockday40x04 DATEC lockdate50x05 MONTHC lockmonth60x06 YEARSC lockyears70x07 CAL_CFG1 Calibrationand configuration80x08 TCH2 Tricklechargeenable90x09 CFG2 Configuration2 Table3. SpecialFunctionRegistersADDRESSREGISTERR EGISTERNAMEDESCRIPTION(HEX)320x20SF KEY1 Specialfunctionkey 1330x21SF KEY2 Specialfunctionkey ReadAfterBackupModeThe time keepingregisterscan take up to 1 secondto updateafterthe RTCswitchesfrombackuppowersupplyto I2C readof the RTCthat startsbeforethe updatehas completedwill returnthe timewhenthe ensurethat the correcttimeis readafterbackupmode,the hostshouldwait longerthan1 secondafterthe mainsupplyis V and (address= 0x00)[reset= 0 XXXXXXb]Description Clocksecondsand STOPbitFigure9.