SLUUBY1B December 2020 – April 2022 BQ76942
The BQ76942 device integrates a diagnostic check on the voltage references used by the device. VREF2 is used by the coulomb counter and LDOs, including the REG18 LDO. The REG18 LDO voltage is periodically measured using the voltage ADC (using VREF1 as its reference) and can be read back in bytes 0-1 of the 0x0075 DASTATUS5() subcommand. This command should normally report a value of approximately 29137. If it differs significantly from this, it may indicate that one reference has changed in value significantly relative to the other, meaning reported measurements may no longer be accurate. This ratio is monitored periodically and, if the value is below 26223 or above 32051 for four seconds, the device can trigger a VREF PF (VREF) and disable the battery pack. This PF can be enabled by setting the Settings:Permanent Failure:Enabled PF C[VREF] and Settings:Manufacturing:Mfg Status Init[PF_EN] configuration bits.