ZHCSU23A October 2023 – December 2023 BQ25638
PRODUCTION DATA
BQ25638 has three built-in safety timers to prevent extended charging cycle due to abnormal battery conditions. The fast charge safety timer and pre-charge safety timers are set through I2C CHG_TMR and PRECHG_TMR fields, respectively. The trickle charge timer is fixed as 1 hour.
The trickle charging, pre-charging and fast charging safety timers can be disabled by setting EN_SAFETY_TMRS = 0. EN_SAFETY_TMRS can be enabled anytime regardless of which charging stage the charger is in. Each timer will start to count as soon as the following two conditions are simultaneously true: EN_SAFETY_TMRS=1 and the corresponding charging stage is active.
When either the fast charging, trickle charging or pre-charging safety timer expires, the SAFETY_TMR_STAT and SAFETY_TMR_FLAG bits are set to 1.
Events that cause a reduction in charging current will also cause the charging safety timer to count at half-clock rate if EN_TMR2X bit is set.
During faults which suspend charging, the charge, pre-charge and trickle safety timers are also suspended, regardless of the state of the EN_TMR2X bit. Once the fault goes away, charging resumes and the safety timer resumes where it stopped.
The charging safety timer and the charging termination can be disabled at the same time. Under this condition, the charging will keep running until it is disabled by the host.