SLUUCF2C January 2021 – May 2022 BQ769142
The BQ769142 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 a 0 second to 65535 second in 1-s 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 turns 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 recovers (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 BQ769142 device can be configured to disable or toggle the external REG1 and REG2 LDOs when the fault occurs. Based on Settings:Configuration:HWD Regulator Options, the device can either leave the LDOs unchanged, disable the LDOs indefinitely, or disable the LDOs for a time period up to 15 s, then enable them again. This is controlled using the Settings:Configuration:HWD Regulator Options configuration register.