The device is a host controlled charger, but it can operate in default mode without host management. In default mode, the device can be used as an autonomous charger with no host or while the host is in sleep mode. When the charger is in default mode, the WATCHDOG_FAULT bit is HIGH. When the charger is in host mode, the WATCHDOG_FAULT bit is LOW.

After power-on-reset, the device starts in default mode with watchdog timer expired, or default mode. All registers are in the default settings.

In default mode, the device keeps charging the battery with the 10-hour fast charging safety timer. At the end of the 10-hour, charging is stopped and the buck converter continues to operate to supply system load. Any write command to the device transitions the charger from default mode to host mode. All device parameters can be programmed by the host. To keep the device in host mode, the host has to reset the watchdog timer by writing a 1 to the WD_RST bit before the watchdog timer expires (WATCHDOG_FAULT bit is set), or disable the watchdog timer by setting the WATCHDOG bits = 00.

All device parameters can be programmed by the host. To keep the device in host mode, the host has to reset the watchdog timer by writing a 1 to the WD_RST bit before the watchdog timer expires (WATCHDOG_FAULT bit is set), or disable the watchdog timer by setting the WATCHDOG bits = 00.

Figure 8-15 Watchdog Timer Flow Chart