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