Charging cycle

Host software enables charging through register BCHGENABLESET. Battery charging starts when VBUS voltage is present and higher than VBAT by at least VBUS_VALIDR. Charging stops in case VBUS-VBAT is less than VBUS_VALIDF either because VBUS drops or VBAT rises. Once charging has started, host software must use register EVENTSBCHARGER0CLR to initialize battery charger events.

When charging is enabled, charging will not start if the battery voltage is less than VBAT_LOW. Charging batteries with a voltage lower than VBAT_LOW is enabled by setting register BCHGVBATLOWCHARGE. When charging starts, it enters trickle charging. Constant current charging starts when the battery voltage is above V_{TRICKLE_FAST}. After the battery voltage reaches V_TERM, the charger enters constant voltage charging. The battery voltage is maintained while monitoring current flow into the battery. When the current into the battery drops below I_TERM, charging is complete. Charging is disabled using register BCHGENABLECLR.

If charging is enabled on a fully charged battery, up to 100 ms of trickle charge and up to 4 ms of constant current charging is applied.

Flow chart of charging cycle — Figure 1. Charging cycle flow chart

Note: Events EVENTBATDETECTED and EVENTBATLOST and status bit BATTERYDETECTED are not available.

Note: When attempting to start charging when VBUS is present but no battery is connected, the host software will see repeated charger events (such as EVENTCHGCOMPLETED).