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5.7POWERMODES
5.7.1NORMALMODE
5.7.2SLEEPMODE
5.7.3BATINSERTCHECKMODE
bq27500
bq27501
System-SideImpedanceTrack™FuelGauge
SLUS785–SEPTEMBER2007
Thebq27500/1hasfourpowermodes:NORMAL,SLEEP,HIBERNATE,andBATINSERTCHECK.In
NORMALmode,thebq27500/1isfullypoweredandcanexecuteanyallowabletask.InSLEEPmode,the
fuelgaugeexistsinareduced-powerstate,periodicallytakingmeasurementsandperformingcalculations.
InHIBERNATEmode,thefuelgaugeisinitslowestpowerstate,butcanbewokenupbycommunication
activityorcertainI/Oactivity.Finally,theBATINSERTCHECKmodeisapowered-up,butlow-power
halted,state,wherethebq27500/1resideswhennobatteryisinsertedintothesystem.
TherelationshipbetweenthesemodesisshowninFigure5-2.
ThefuelgaugeisinNORMALModewhennotinanyotherpowermode.Duringthismode,
AverageCurrent(),Voltage()andTemperature()measurementsaretaken,andtheinterfacedatasetis
updated.Decisionstochangestatesarealsomade.Thismodeisexitedbyactivatingadifferentpower
mode.
BecausethegaugeconsumesthemostpowerinNORMALmode,theImpedanceTrack™algorithm
minimizesthetimethefuelgaugeremainsinthismode.
SLEEPmodeisenteredautomaticallyifthefeatureisenabled(OperationConfiguration[SLEEP])=1)
andAverageCurrent()isbelowtheprogrammablelevelSleepCurrent.OnceentryintoSLEEPmode
hasbeenqualified,butpriortoenteringit,thebq27500/1performsanADCautocalibrationtominimize
offset.
DuringSLEEPmode,thebq27500/1periodicallytakesdatameasurementsandupdatesitsdataset.
However,amajorityofitstimeisspentinanidlecondition.
Thebq27500/1exitsSLEEPifanyentryconditionisbroken,specificallywhen(1)AverageCurrent()rises
aboveSleepCurrent,or(2)acurrentinexcessofI
WAKE
throughR
SENSE
isdetected.
Intheeventthatabatteryisremovedfromthesystemwhileachargerispresent(andpoweringthe
gauge),ImpedanceTrack™updatesarenotnecessary.Hence,thefuelgaugeentersastatethatchecks
forbatteryinsertionanddoesnotcontinueexecutingtheImpedanceTrack™algorithm.
Thismodeisahalted-CPUstatethatoccurswhenanadapter,orotherpowersource,ispresenttopower
thebq27500/1(andsystem),yetnobatteryhasbeendetected.Whenbatteryinsertionisdetected,a
seriesofinitializationactivitiesbegin,whichinclude:OCVmeasurement,settingtheBAT_GDpin,and
selectingtheappropriatebatteryprofiles.
Somecommands,issuedbyasystemprocessor,canbeprocessedwhilethebq27500/1ishaltedinthis
mode.Thegaugewillwakeuptoprocessthecommand,thenreturntothehaltedstateawaitingbattery
insertion.
SubmitDocumentationFeedbackFUNCTIONALDESCRIPTION27