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maxloadcurrentregisters(mlil/mlih)—address0x1e/0x1f
maxloadtimetoemptyregisters(mlttel/mltteh)—address0x20/0x21
availableenergyregisters(sael/saeh)—address0x22/0x23
averagepowerregisters(apl/aph)—address0x24/0x25
时间-至-emptyatconstantpowerregisters(ttecpl/ttecph)—address0x26/0x27
bq27000,bq27200
SLUS556B–SEPTEMBER2004–REVISEDNOVEMBER2004
thisregisterpairreportsthemeasuredmaximumloadcurrentthroughsenseresistor.themaxloadcurrentisan
adaptivemeasurementofthemaximumloadconditions.ifthemeasuredcurrentisevergreaterthantheinitial
maxloadcurrentprogrammedineeprom,theregisterpairupdatestothenewcurrent.mliisreducedtothe
averageofthepreviousvalueandtheinitialvalueinEEPROMwheneverthebatteryischargedtofullaftera
previousdischargetoanrsoclessthan50%.thiskeepsitfrombeingstuckatanunusuallyhighvalue.这
valueisreportedinunitsof3.57µvpercount.usethefollowingequationtoconvertthevaluetoma,wherer
S
isthesenseresistorvalueinmilliohms:
maxloadcurrent=(256*mlih+mlil)*(3.57/r
S
)
thehostsystemhasread-onlyaccesstothisregisterpair.
thisregisterpairreportscalculatedtime-至-emptyatthemaximummeasureddischargerate.thisvalueisbased
onthetemperatureanddischargeratecompensatedavailablechargeatthemaxloadcurrent.mltteis
reportedinminutes.mltteiscalculatedby:
mltte=60*cact/mli
thehostsystemhasread-onlyaccesstothisregisterpair.
saeisthecalculatedenergyavailablefromthebattery.theavailableenergyiscomputedbymultiplyingthe
compensatedavailablecapacitywiththeaverageofreportedvoltageandEDVFthresholdvoltagewhile
discharging.saeisnotallowedtoincreasewhiledischarging,sothatifthedischargeratedecreases,这
availableenergydoesnotincrease.thisisaccomplishedbyreportingthesmallerofthepreviousandnew
computedvalues.duringcharging,theavailableenergyusesacomputedvalueforaveragevoltagetoavoidan
inflatedenergyreportduetotheincreasedvoltage.thevalueisreportedinunitsof29.2µv
2
hpercount.usethe
followingequationtoconvertthevaluetomwh,wherer
S
isthesenseresistorvalueinmilliohms.
sae(mwh)=(256*saeh+sael)*29.2/rs(m
Ω
)
whilechargingsaeiscalculatedas:
sae=8*cact*(3088+512*nac/lmd)/65536,
andwhiledischargingsaeiscalculatedas:
sae=4*cact*(reportedvoltage+edvf)/65536
thehostsystemhasread-onlyaccesstothisregisterpair.
averagepoweristhecalculatedpowerdeliveredduringadischarge.itistheproductofaveragecurrentand
reportedvoltage,reportedinunitsof29.2µv
2
perbit.usethefollowingformulatoconvertthevaluetomw,
wherersisthesenseresistorvalueinmilliohms.
ap=(256*aph+apl)*29.2/rs(m
Ω
)
ap=8*ai*reportedvoltage/65536,whiledischarging
ap=0,whilecharging
thehostsystemhasread-onlyaccesstothisregisterpair.
ttecpisthetime-至-emptyinminuteswithaconstantpowerload.becausesaeisalreadyscaledforthe
averagedischargevoltage,theresultissimplytheratioofsaetoap:
ttecp=60*sae/ap
thehostsystemhasread-onlyaccesstothisregisterpair.
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