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bq27500
bq27501System-Side Impedance Track™ Fuel Gauge
SLUS785 – SEPTEMBER 2007
4.1.1.7 NominalAvailableCapacity( ): 0x0c/0x0d
This read-only command pair returns the uncompensated (no or light load) battery capacity remaining.Units are mAh per bit.
4.1.1.8 FullAvailableCapacity( ): 0x0e/0x0f
This read-only command pair returns the uncompensated (no or light load) capacity of the battery whenfully charged. Units are mAh per bit. FullAvailableCapacity( ) is updated at regular intervals, as specifiedby the IT algorithm.
4.1.1.9 RemainingCapacity( ): 0x10/0x11
This read-only command pair returns the compensated battery capacity remaining. Units are mAh per bit.
4.1.1.10 FullChargeCapacity( ): 0x12/13
This read-only command pair returns the compensated capacity of the battery when fully charged. Unitsare mAh per bit. FullChargeCapacity( ) is updated at regular intervals, as specified by the IT algorithm.
4.1.1.11 AverageCurrent( ): 0x14/0x15
This read-only command pair returns a signed integer value that is the average current flow through thesense resistor. It is updated every 1 second. Units are mA per bit.
4.1.1.12 TimeToEmpty( ): 0x16/0x17
This read-only function returns an unsigned integer value of the predicted remaining battery life at thepresent rate of discharge, in minutes. A value of 65535 indicates battery is not being discharged.
4.1.1.13 TimeToFull( ): 0x18/0x19
This read-only function returns an unsigned integer value of predicted remaining time until the batteryreaches full charge, in minutes, based upon AverageCurrent( ). The computation accounts for the tapercurrent time extension from the linear TTF computation based on a fixed AverageCurrent( ) rate of chargeaccumulation. A value of 65535 indicates the battery is not being charged.
4.1.1.14 StandbyCurrent( ): 0x1a/0x1b
This read-only function returns a signed integer value of the measured standby current through the senseresistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby currentprogrammed in Initial Standby, and after spending some time in standby, reports the measured standbycurrent.
The register value is updated every 1 second when the measured current is above the Deadband (3mAdefault) and is less than or equal to 2 x Initial Standby. The first and last values that meet this criteria arenot averaged in, since they may not be stable values. To approximate a 1 minute time constant, each newStandbyCurrent( ) value is computed as follows:
StandbyCurrent( )
NEW
= (239/256) ×StandbyCurrent( )
OLD
+ (17/256) ×AverageCurrent( ).
4.1.1.15 StandbyTimeToEmpty( ): 0x1c/0x1d
This read-only function returns an unsigned integer value of the predicted remaining battery life at thestandby rate of discharge, in minutes. The computation uses Nominal Available Capacity (NAC), theuncompensated remaining capacity, for this computation. A value of 65535 indicates battery is not beingdischarged.
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