Datasheet

BatteryDetectionusingtheBI/TOUTPin
TEMPERATUREMEASUREMENT
OVER-TEMPERATUREINDICATION
Over-Temperature:Charge
Over-Temperature:Discharge
CHARGINGANDCHARGE-TERMINATIONINDICATORS
DetectingChargeTermination
ChargeInhibitandSuspend
bq27510-G1
SLUS927–APRIL2009..................................................................................................................................................................................................... www.ti.com
Duringpower-uporhibernateactivities,oranyotheractivitywherethebq27510needstodeterminewhethera
batteryisconnectedornot,thefuelgaugeappliesatestforbatterypresence.First,theBI/TOUTpinisputinto
high-Zstatus.Theweak1.8MΩpull-upresistorwillkeepthepinhighwhilenobatteryispresent.Whenabattery
isinserted(orisalreadyinserted)intothesystemdevice,theBI/TOUTpinwillbepulledlow.Thisstateis
detectedbythefuelgauge,whichpollsthispineverysecondwhenthegaugehaspower.Abattery-disconnected
statusisassumedwhenthebq27510readsathermistorvoltagethatisnear2.5V.
Thebq27510measuresbatterytemperatureviaitsTSinput,inordertosupplybatterytemperaturestatus
informationtothefuelgaugingalgorithmandcharger-controlsectionsofthegauge.Alternatively,itcanalso
measureinternaltemperatureviaitson-chiptemperaturesensor,butonlyifthe[TEMPS]bitofOperation
Configurationregisteriscleared.
Regardlessofwhichsensorisusedformeasurement,asystemprocessorcanrequestthecurrentbattery
temperaturebycallingtheTemperature()function(seeSectionStandardDataCommands,forspecific
information).
Theexternaltemperaturemeasurementcircuitmustusea103AT-typethermistor.Additionalcircuitinformation
forconnectingthisthermistortothebq27510isshowninSectionReferenceSchematic.
Ifduringcharging,Temperature()reachesthethresholdofOTChgforaperiodofOTChgTimeand
AverageCurrent()>ChgCurrentThreshold,thenthe[OTC]bitofFlags()isset.WhenTemperature()fallsto
OTChgRecovery,the[OTC]ofFlags()isreset.
IfOTChgTime=0thenfeatureiscompletelydisabled.
Ifduringdischarging,Temperature()reachesthethresholdofOTDsgforaperiodofOTDsgTimeand
AverageCurrent()≤-DsgCurrentThreshold,thenthe[OTD]bitofFlags()isset.WhenTemperature()fallsto
OTDsgRecovery,the[OTD]ofFlags()isreset.
IfOTDsgTime=0thenfeatureiscompletelydisabled.
Forproperbq27510operation,thecellchargingvoltagemustbespecifiedbytheuser.Thedefaultvalueforthis
variableisChargingVoltage=4200mV.
Thebq27510detectschargeterminationwhen(1)during2consecutiveperiodsofCurrentTaperWindow,the
AverageCurrent()is<TaperCurrent,(2)duringthesameperiods,theaccumulatedchangeincapacity>Min
TaperCharge/CurrentTaperWindow,and(3)Voltage()>ChargingVoltage–TaperVoltage.Whenthis
occurs,the[CHG]bitofFlags()iscleared.Also,ifthe[RMFCC]bitofOperationConfigurationisset,and
RemainingCapacity()issetequaltoFullChargeCapacity().
Thebq27510canindicatewhenbatterytemperaturehasfallenbeloworrisenabovepredefinedthresholds
ChargeInhibitTempLoworChargeInhibitTempHigh,respectively.Inthismode,the[CHG_INT]bitisset
andtheBAT_GDpinisdesertedtoindicatethiscondition.The[CHG_INT]bitisclearedandtheBAT_GDpinis
assertedoncethebatterytemperaturereturnstotherange[ChargeInhibitTempLow+TempHys,Charge
InhibitTempHigh–TempHys].
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