BQ27541-V200_17 Datasheet, PDF (15/46 Pages) Texas Instruments – Single Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration

Not Recommended for New Designs
bq27541-V200
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SLUSA11B – FEBRUARY 2010 – REVISED SEPTEMBER 2013
StandbyCurrent( ): 0x1a/0x1b
This read-only function returns a signed integer value of the measured standby current through the sense
resistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby current programmed
in Initial Standby, and after spending some time in standby, reports the measured standby current.
The register value is updated every 1 second when the measured current is above the Deadband and is less
than or equal to 2 x Initial Standby. The first and last values that meet this criteria are not averaged in, since
they may not be stable values. To approximate a 1 minute time constant, each new StandbyCurrent( ) value is
computed by taking approximate 93% weight of the last standby current and approximate 7% of the current
measured average current.
StandbyTimeToEmpty( ): 0x1c/0x1d
This read-only function returns an unsigned integer value of the predicted remaining battery life at the standby
rate of discharge, in minutes. The computation uses Nominal Available Capacity (NAC), the uncompensated
remaining capacity, for this computation. A value of 65,535 indicates battery is not being discharged.
MaxLoadCurrent( ): 0x1e/0x1f
This read-only function returns a signed integer value, in units of mA, of the maximum load conditions. The
MaxLoadCurrent( ) is an adaptive measurement which is initially reported as the maximum load current
programmed in Initial Max Load Current. If the measured current is ever greater than Initial Max Load
Current, then MaxLoadCurrent( ) updates to the new current. MaxLoadCurrent( ) is reduced to the average of
the previous value and Initial Max Load Current whenever the battery is charged to full after a previous
discharge to an SOC less than 50%. This prevents the reported value from maintaining an unusually high value.
MaxLoadTimeToEmpty( ): 0x20/0x21
This read-only function returns an unsigned integer value of the predicted remaining battery life at the maximum
load current discharge rate, in minutes. A value of 65,535 indicates that the battery is not being discharged.
AvailableEnergy( ): 0x22/0x23
This read-only function returns an unsigned integer value of the predicted charge or energy remaining in the
battery. The value is reported in units of mWh.
AveragePower( ): 0x24/0x25
This read-word function returns an unsigned integer value of the average power of the current discharge. It is
negative during discharge and positive during charge. A value of 0 indicates that the battery is not being
discharged. The value is reported in units of mW.
TimeToEmptyAtConstantPower( ): 0x26/0x27
This read-only function returns an unsigned integer value of the predicted remaining operating time if the battery
is discharged at the AveragePower( ) value in minutes. A value of 65,535 indicates AveragePower( ) = 0. The
fuel gauge automatically updates TimeToEmptyatConstantPower( ) based on the AveragePower( ) value every
1s.
Internal_Temp( ): 0x28/0x29
This read-only function returns an unsigned integer value of the measured internal temperature of the device in
units of 0.1K measured by the fuel gauge.
CycleCount( ): 0x2a/0x2b
This read-only function returns an unsigned integer value of the number of cycles the battery has experienced
with a range of 0 to 65,535. One cycle occurs when accumulated discharge ≥ CC Threshold.
StateOfCharge( ): 0x2c/0x2d
This read-only function returns an unsigned integer value of the predicted remaining battery capacity expressed
as a percentage of FullChargeCapacity( ), with a range of 0 to 100%.
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