8.3.7.5 Charging Safety Timer

The device has built-in safety timer to prevent extended charging cycle due to abnormal battery conditions.

During input voltage, current or thermal regulation, the safety timer counts at half clock rate as the actual charge current is likely to be below the setting. For example, if the charger is in input current regulation throughout the whole charging cycle, and the safety timer is set to 12 hours, then the timer will expire in 24 hours.

During faults which disable charging, or supplement mode, timer is suspended. Once the fault goes away, safety timer resumes. If the charging cycle is stopped and started again, the timer gets reset.

The safety timer is reset for the following events:

1. Charging cycle stop and restart (toggle CE pin, or charged battery falls below recharge threshold).
2. BAT voltage changes from pre-charge to fast-charge or vice versa.

The precharge safety timer (fixed 2hr counter that runs when VBAT < V_{BAT_LOWV}), follows the same rules as the fast-charge safety timer in terms of getting suspended, reset, and counting at half-rate.