JAJSHN4D June 2019 – December 2021 BQ25618 , BQ25619
PRODUCTION DATA
The device has a built-in safety timer to prevent an extended charging cycle due to abnormal battery conditions. The safety timer is 2 hours when the battery is below the VBATLOWV threshold and 10 hours (10/20 hours in REG05[2] ) when the battery is higher than the VBATLOWV threshold. When the safety timer expires, the STAT pin is blinking at 1 Hz to report a safety timer expiration fault.
The user can program the fast charge safety timer through I2C (CHG_TIMER bit REG05[2]). When the safety timer expires, the fault register CHRG_FAULT bits (REG09[5:4]) are set to 11 and an INT is asserted to the host. The safety timer (both fast charge and precharge) can be disabled through I2C by setting the EN_TIMER bit.
During IINDPM/VINDPM regulation, thermal regulation, or JEITA cool/warm when fast charge current is reduced, the safety timer counts at a half clock rate, because the actual charge current is likely below the setting. For example, if the charger is in input current regulation (IINDPM_STAT = 1) throughout the whole charging cycle, and the safety time is set to 10 hours, the safety timer will expire in 20 hours. This half clock rate feature can be disabled by writing 0 to the TMR2X_EN bit.
During faults of BAT_FAULT, NTC_FAULT that lead to charging suspend, the safety timer is suspended as well. Once the fault goes away, the timer resumes. If the user stops the current charging cycle, and starts it again, the timer gets reset (toggle of CE pin or CHG_CONFIG bit).