bq2002

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1Features➤Fastchargeofnickelcadmiumornickel-metalhydridebatter-ies➤DirectLEDoutputdisplayschargestatus➤Fast-chargeterminationby-∆V,maximumvoltage,maximumtemperature,andmaximumtime➤Internalband-gapvoltageref-erence➤Optionaltop-offcharge➤Selectablepulsetricklechargerates➤Low-powermode➤8-pin300-milDIPor150-milSOICGeneral DescriptionThebq2002andbq2002/FFast-ChargeICsarelow-costCMOSbattery-chargecontrollersprovidingreliablechargeterminationforbothNiCdandNiMHbatteryapplications.Controllingacurrent-limitedorconstant-currentsupplyallowsthebq2002/Ftobethebasisforacost-effectivestand-aloneorsystem-integratedcharger.Thebq2002/Fintegratesfastchargewithoptionaltop-offandpulsed-tricklecon-trolinasingleICforchargingoneormoreNiCdorNiMHbatterycells.

Fastchargeisinitiatedonapplicationofthechargingsupplyorbatteryre-placement.Forsafety,fastchargeisinhibitedifthebatterytemperatureandvoltageareoutsideconfiguredlimits.

Fastchargeisterminatedbyanyofthefollowing:

nPeakvoltagedetection(PVD)

nNegativedeltavoltage(-∆V)nMaximumvoltagenMaximumtemperaturenMaximumtimeAfterfastcharge,thebq2002/Fop-tionallytops-offandpulse-tricklesthebatteryperthepre-configuredlimits.FastchargemaybeinhibitedusingtheINHpin.Thebq2002/Fmayalsobeplacedinlow-standby-powermodetoreducesystempowerconsumption.

Thebq2002Fdiffersfromthebq2002onlyinthataslightlydiffer-entsetoffast-chargeandtop-offtimelimitsisavailable.Alldiffer-encesbetweenthetwoICsareillus-tratedinTable1.

NiCd/NiMH Fast-Charge Management ICsbq2002/F

TMTimer mode select inputLEDCharging status output

BATBattery voltage inputVSSSystem ground

1PN-200201.eps8-Pin DIP orNarrow SOIC234 8765TMLEDBATVSSCCINHVCC

TS

TSTemperaturesenseinputVCCSupply voltage inputINHCharge inhibit inputCCCharge control output

Pin ConnectionsPin Names

bq2002/F Selection GuidePart No.TCOHTFLTF-∆VPVDFast ChargetMTOTop-OffMaintenancebq20020.5∗VCCNoneNone✔C/2160C/32C/64✔1C80C/16C/64✔2C40NoneC/32

bq2002F0.5∗VCCNoneNone✔C/2160C/32C/64✔1C100C/16C/64✔2C55NoneC/32

SLUS131 – APRIL 2009 Pin DescriptionsTMTimermodeinputAthree-levelinputthatcontrolsthesettingsforthefastchargesafetytimer,voltageter-minationmode,top-off,pulse-trickle,andvoltagehold-offtime.

LEDChargingoutputstatusOpen-drainoutputthatindicatesthechargingstatus.

BATBatteryinputvoltageThebatteryvoltagesenseinput.Theinputtothispiniscreatedbyahigh-impedancere-sistordividernetworkconnectedbetweenthepositiveandnegativeterminalsofthebattery.

VSSSystemground

TSTemperaturesenseinputInputforanexternalbatterytemperaturemonitoringthermistor.

VCCSupplyvoltageinput

5.0V±20%powerinput.INHChargeinhibitinputWhenhigh,INHsuspendsthefastchargeinprogress.Whenreturnedlow,theICre-sumesoperationatthepointwhereinitiallysuspended.

CCChargecontroloutputAnopen-drainoutputusedtocontrolthechargingcurrenttothebattery.CCswitch-ingtohighimpedance(Z)enableschargingcurrenttoflow,andlowtoinhibitchargingcurrent.CCismodulatedtoprovidetop-off,ifenabled,andpulsetrickle.

Functional DescriptionFigure2showsastatediagramandFigure3showsablockdiagramofthebq2002/F.

BatteryVoltageandTemperatureMeasurements

Batteryvoltageandtemperaturearemonitoredformaximumallowablevalues.Thevoltagepresentedonthebatterysenseinput,BAT,shouldrepresentasingle-cellpotentialforthebatteryundercharge.Aresistor-dividerratioof

RB1RB2= N - 1

isrecommendedtomaintainthebatteryvoltagewithinthevalidrange,whereNisthenumberofcells,RB1istheresistorconnectedtothepositivebatteryterminal,andRB2istheresistorconnectedtothenegativebat-teryterminal.SeeFigure1.

Note:Thisresistor-dividernetworkinputimpedancetoend-to-endshouldbeatleast200kΩandlessthan1MΩ.

Aground-referencednegativetemperaturecoefficientthermistorplacednearthebatterymaybeusedasalow-costtemperature-to-voltagetransducer.ThetemperaturesensevoltageinputatTSisdevelopedusingaresistor-thermistornetworkbetweenVCCandVSS.SeeFigure1.

2

bq2002/F

Fg2002/F01.epsbq2002/FBATVSSNTCbq2002/FVCC

VCCPACK +

TSVSSBAT pin connectionThermistor connectionTM

NTC = negative temperature coefficient thermistor.

RTR3R4RB1

RB2

Mid-levelsetting for TM

Figure 1.Voltage and Temperature Monitoring and TM Pin Configuration