SLUSEC9B October 2020 – July 2024 BQ25618E , BQ25619E
PRODUCTION DATA
The device terminates a charge cycle when the battery voltage is above the recharge threshold, and the current is below termination current. After the charging cycle is completed, the BATFET turns off. The STAT is asserted HIGH to indicate charging done. The converter keeps running to power the system, and BATFET can turn on again to engage Section 8.3.4.3.
If the device is in IINDPM/VINDPM regulation, or thermal regulation, the actual charging current will be less than the termination value. In this case, termination is temporarily disabled.
When termination occurs, STAT pin goes HIGH. The status register CHRG_STAT is set to 11, and an INT pulse is asserted to the host. Termination can be disabled by writing 0 to EN_TERM bit prior to charge termination.
The termination current is set in REG03[3:0]. For small capacity battery, the termination current can be set as low as 20 mA for full charge. Due to the termination current accuracy, the actual termination current may be higher than the termination target. In order to compensate for termination accuracy, a programmable top-off timer can be applied after termination is detected . The top-off timer will follow safety timer constraints, such that if safety timer is suspended, so will the top-off timer. Similarly, if safety timer is doubled, so will the termination top-off timer. TOPOFF_ACTIVE bit reports whether the top off timer is active or not. The host can read CHRG_STAT and TOPOFF_ACTIVE to find out the termination status. STAT pin stays HIGH during top-off timer counting cycle.
The top-off timer settings are read in once termination is detected by the charger. Programming a top-off timer value (01, 10, 11) after termination will have no effect unless a recharge cycle is initiated. The top-off timer will immediately stop if it is disabled (00). An INT is asserted to the host when entering top-off timer segment as well as when top-off timer expires.