SLUUBY1B December 2020 – April 2022 BQ76942
When a cell is severely overdischarged, copper deposition can occur, resulting in very high impedance. If this occurs while the pack is in operation, the BQ76942 device will typically detect this and disable the pack before cells reach this low voltage (based on a SUV PF). However, if the device is in SHUTDOWN mode for an excessively long time period and the cells become overly discharged, the pack could still wake and enable the FETs if a charger were attached. If the FETs were turned on in this condition, the pack voltage would rise sharply due to the charging current, making the cells appear healthy. The CUDEP Permanent Fail is used to identify this condition and disable the pack. When enabled, this check keeps the FETs disabled at power up from SHUTDOWN mode until each cell voltage is greater than or equal to Permanent Fail:CUDEP:Threshold for Permanent Fail:CUDEP:Delay seconds. If any cell voltage is below Permanent Fail:CUDEP:Threshold for Permanent Fail:CUDEP:Delay seconds, the CUDEP Permanent Fail is triggered. This PF check is enabled by setting the Settings:Permanent Failure:Enabled PF A[CUDEP] and Settings:Manufacturing:Mfg Status Init[PF_EN] configuration bits.