Datasheet

bq27541-G1

SLUSAL6C –NOVEMBER 2011–REVISED OCTOBER 2012

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CHARGING AND CHARGE TERMINATION INDICATION

Detection Charge Termination

For proper bq27541-G1 operation, the cell charging voltage must be specified by the user. The default value for

this variable is in the data flash Charging Voltage.

The bq27541-G1 detects charge termination when (1) during 2 consecutive periods of Current Taper Window,

the AverageCurrent( ) is < Taper Current, (2) during the same periods, the accumulated change in capacity >

0.25mAh / Current Taper Window, and (3) Voltage( ) > Charging Voltage – Taper Voltage. When this occurs,

the [CHG] bit of Flags( ) is cleared. Also, if the [RMFCC] bit of Pack Configuration is set, RemainingCapacity( )

is set equal to FullChargeCapacity( ). When TCA_Set is set to -1, it disables the use of the charger alarm

threshold. In that case, TerminateCharge is set when the taper condition is detected. When FC_Set is set to -1, it

disables the use of the full charge detection threshold. In that case, the [FC] bit is not set until the taper condition

is met.

Charge Inhibit

The bq27541-G1 can indicate when battery temperature has fallen below or risen above predefined thresholds

(Charge Inhibit Temp Low and Charge Inhibit Temp High, respectively). In this mode, the [CHG_INH] of

Flags( ) is made high to indicate this condition, and is returned to its low state, once battery temperature returns

to the range [Charge Inhibit Temp Low + Temp Hys, Charge Inhibit Temp High – Temp Hys].

POWER MODES

The bq27541-G1 has three power modes: NORMAL, SLEEP, and HIBERNATE. In NORMAL mode, the

bq27541-G1 is fully powered and can execute any allowable task. In SLEEP mode the fuel gauge exists in a

reduced-power state, periodically taking measurements and performing calculations. Finally, in HIBERNATE

mode, the fuel gauge is in a very low power state, but can be awoken by communication or certain I/O activity.

The relationship between these modes is shown in . Details are described in the sections that follow.

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