8.4.7 Autocalibration

The bq27545-G1 provides an autocalibration feature that will measure the voltage offset error across SRP and SRN from time-to-time as operating conditions change. It subtracts the resulting offset error from normal sense resistor voltage, V_SR, for maximum measurement accuracy.

Autocalibration of the ADC begins on entry to SLEEP mode, except if Temperature() is ≤ 5°C or Temperature() ≥ 45°C.

The fuel gauge also performs a single offset calibration when (1) the condition of AverageCurrent() ≤ 100 mA and (2) {voltage change because last offset calibration ≥ 256 mV} or {temperature change because last offset calibration is greater than 8°C for ≥ 60 seconds}.

Capacity and current measurements will continue at the last measured rate during the offset calibration when these measurements cannot be performed. If the battery voltage drops more than 32 mV during the offset calibration, the load current has likely increased considerably; hence, the offset calibration will be aborted.