The BQ77307 includes several checks for diagnostic purposes. Some of these will trigger a protection fault, but they generally do not include an alert phase with programmable delay period, they will immediately trigger a fault when they are detected. They are not all autonomously recoverable, but some can be manually recovered using a subcommand sent by the host. For more detail on each diagnostic, see the BQ77307 Technical Reference Manual.

VREF1 vs VREF2 Check—The device performs a regular comparison of the ratio between the two internal voltage references and can trigger a fault if the result is outside an acceptable range.

VSS Check—The device also includes a regular check of the VSS voltage, comparing the result to the expected result, in order to implement the VSSF Diagnostic Protection.

REGOUT Check—The REGOUT LDO generates a flag if an error is detected, such as the regulator is in short circuit current limit. When detected, the device triggers the REGOUT Diagnostic Fault and can disable FETs based on settings.

LFO Integrity Check—The device integrates a special hardware block that monitors if the LFO stops oscillating or drops significantly in frequency versus its expected value. If this is detected, the device immediately transitions into SHUTDOWN mode.

Internal Factory Trim Check—The device includes a check of the digital trim and setting information within the device at initial power-up or after any full reset. If an error is detected during this check, the device will immediately transition to SHUTDOWN mode.

Hardware Overtemperature Detector—The device integrates a hardware overtemperature detection circuit, which determines when the die temperature passes an excessive temperature of approximately 120°C. If this detector triggers, the device will automatically begin the sequence to enter SHUTDOWN, based on the configuration setting.