Filter
Top Products
www.ti.com
4GENERALDESCRIPTION
bq27500
bq27501
System-SideImpedanceTrack™FuelGauge
SLUS785–SEPTEMBER2007
Thebq27500/1accuratelypredictsthebatterycapacityandotheroperationalcharacteristicsofasingle
Li-basedrechargeablecell.Itcanbeinterrogatedbyasystemprocessortoprovidecellinformation,such
asState-of-Charge(SOC),Time-to-Empty(TTE)andTime-to-Full(TTF).
Informationisaccessedthroughaseriesofcommands,calledStandardCommands.Furthercapabilities
areprovidedbytheadditionalExtendedCommandsset.Bothsetsofcommands,indicatedbythegeneral
formatCommand(),areusedtoreadandwriteinformationcontainedwithinthebq27500/1controland
statusregisters,aswellasitsdataflashlocations.Commandsaresentfromsystemtogaugeusingthe
bq27500/1’sI
2
Cserialcommunicationsengine,andcanbeexecutedduringapplicationdevelopment,
packmanufacture,orend-equipmentoperation.
Cellinformationisstoredinthebq27500/1innon-volatileflashmemory.Manyofthesedataflash
locationsareaccessibleduringapplicationdevelopment.Theycannotbeaccesseddirectlyduring
end-equipmentoperation.Accesstotheselocationsisachievedbyeitheruseofthebq27500/1's
companionevaluationsoftware,throughindividualcommands,orthroughasequenceofdata-flash-access
commands.Toaccessadesireddataflashlocation,thecorrectdataflashsubclassandoffsetmustbe
known.
Thebq27500/1provides96bytesofuser-programmabledataflashmemory,partitionedinto332-byte
blocks:ManufacturerInfoBlockA,ManufacturerInfoBlockB,andManufacturerInfoBlockC.This
dataspaceisaccessedthroughadataflashinterface.Forspecificsonaccessingthedataflash,see
Section4.3ManufacturerInformationBlocks.
Thekeytothebq27500/1’shigh-accuracygasgaugingpredictionisTexasInstrument’sproprietary
ImpedanceTrack™algorithm.Thisalgorithmusescellmeasurements,characteristics,andpropertiesto
createstate-of-chargepredictionsthatcanachievelessthan1%erroracrossawidevarietyofoperating
conditionsandoverthelifetimeofthebattery.
Thebq27500/1measurescharge/dischargeactivitybymonitoringthevoltageacrossasmall-valueseries
senseresistor(5mΩto20mΩtyp.)locatedbetweenthesystem'sVssandthebattery’sPACK–terminal.
Whenacellisattachedtothebq27500/1,cellimpedanceiscomputed,basedoncellcurrent,cellOpen
CircuitVoltage(OCV),andcellvoltageunderloadingconditions.
Thebq27500/1canuseanNTCthermistor(defaultisSemitec103AT)fortemperaturemeasurement,or
canalsobeconfiguredtouseitsinternaltemperaturesensor.Thebq27500/1usestemperaturetomonitor
thebattery-packenvironment,whichisusedforfuelgaugingandcellprotectionfunctionality.
Tominimizepowerconsumption,thebq27500/1hasseveralpowermodes:NORMAL,SLEEP,
HIBERNATE,andBATINSERTCHECK.Thebq27500/1passesautomaticallybetweenthesemodes,
dependingupontheoccurrenceofspecificevents,thoughasystemprocessorcaninitiatesomeofthese
modesdirectly.MoredetailscanbefoundintheSection5.7POWERMODES.
NOTE
FORMATTINGCONVENTIONSINTHISDOCUMENT:
Commands:italicswithparenthesesandnobreakingspaces,e.g.RemainingCapacity().
DataFlash:italics,bold,andbreakingspaces,e.g.DesignCapacity
RegisterBitsandFlags:bracketsonly,e.g.[TDA]
DataFlashBits:italicsandbold,e.g:[LED1]
Modesandstates:ALLCAPITALS,e.g.UNSEALEDmode.
8GENERALDESCRIPTIONSubmitDocumentationFeedback