7.3.11.3 Charging Safety Timer

The device has built-in safety timer to prevent extended charging cycle due to abnormal battery conditions. The user can program fast charge safety timer through I²C (CHG_TIMER bits). When safety timer expires, the TMR_FLAG bit is set to 1, and an INT pulse is asserted to the host. The safety timer feature can be disabled via I²C using EN_TIMER bit.

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 register setting. For example, if the charger is in input current regulation (IINDPM_STAT = 1) throughout the whole charging cycle, and the safety timer is set to 5 hours, then the timer will expire in 10 hours. This half clock rate feature can be disabled by setting TMR2X_EN = 0. Changing the TMR2X_EN bit while the device is running has no effect on the safety timer count, other than forcing the timer to count at half the rate under the conditions dictated above.