The BQ76922 device integrates a Host Watchdog (HWD) Protection that triggers a fault when no communications are received for a programmable delay HWD_DLY. The HWD_DLY delay is programmable from 0-sec to 65535-sec in 1-sec steps using the Protections:HWD:Delay configuration register. The HWD protection is enabled using the Settings:Protection:Enabled Protections C:[HWDF] configuration bit.

When an HWD fault is triggered, the device will turn off the DSG FET, the CHG FET, or both FETs if configured for autonomous FET control, based on settings in Settings:Protection:DSG FET Protections C[HWDF] and Settings:Protection:CHG FET Protections C[HWDF]. The device will recover (if configured for autonomous recovery) when valid communications are received. Note that there is no safety alert for the HWD, only a safety status in Safety Status C[HWDF].

If there is a concern that the HWD fault is caused by the host processor no longer operating properly, the BQ76922 device can be configured to disable or toggle the external REG1 LDO when the fault occurs. Based on Settings:Configuration:HWD Regulator Options, the device can either leave the LDO unchanged, disable the LDO indefinitely, or disable the LDO for a time period up to 15-sec, then re-enable it again. This is controlled using the Settings:Configuration:HWD Regulator Options configuration register.

Note: if the toggling is enabled and the device disables the LDO after a HWD fault, after the toggle delay is completed the device will recover the LDO to their state in Settings:REG1 Config[REG1_EN], which may not be its state when the HWD fault occurred.