SLUSDF9 June 2020 BQ25790
The device charges the battery in five phases: trickle charge, pre-charge, constant current, constant voltage, and top-off trickle charging (optional). At the beginning of a charging cycle, the device checks the battery voltage and regulates current/voltage accordingly.
|VBAT||CHARGING CURRENT||REGISTER DEFAULT SETTING||CHRG_STAT|
|< VBAT_SHORT||IBAT_SHORT||100 mA||001|
|VBAT_SHORTZ to VBAT_LOWV||IPRECHG||120 mA||010|
|> VBAT_LOWV||ICHG||2 A (1S and 2S)
1 A (3S and 4S)
If the charger is in DPM regulation or thermal regulation during charging, the actual charging current is less than the programmed value. In this case, termination is temporarily disabled and the charging safety timer is counted at half the clock rate, as explained in Charging Safety Timer.
The BATFET LDO operation can be disabled by setting DIS_LDO = 1. At this condition, the pre-charge current and fast charge current are both regulated by the buck-boost converter PWM current regulation loop. The SYS is not regulated at VSYSMIN any more when the LDO mode is disabled at the low battery voltage condition. When in trickle charge, setting DIS_LDO = 1 does not affect IBAT_SHORT or VSYSMIN operation.
VBAT_LOWV is the battery voltage threshold for the transition from pre-charge to fast charge. It is defined as a ratio of battery voltage regulation limit (VREG). The VBAT_SHORTZ is the battery voltage threshold for the transition from trickle charge to pre-charge, which is fixed value 2.2V.