The BQ76922 device includes optional capability for the customer to calibrate the COV (cell overvoltage) and CUV (cell undervoltage) protection thresholds on the production line, in order to improve threshold accuracy in system or to realize a threshold between the preset thresholds available from the device.

This calibration is performed while the device is in CONFIG_UPDATE mode. To calibrate the COV threshold, an external voltage is first applied between VC5 and VC4A that is equal to the desired COV threshold. Next, a subcommand is sent by the host, which causes the BQ76922 device to perform a search for the appropriate calibration coefficients to realize a COV threshold at or close to the applied voltage level. When this search is completed, the resulting calibration coefficient is returned by the subcommand and automatically written into a data memory configuration parameter. If this parameter is nonzero, the device will not use its factory trim settings but will instead use this value.

The CUV threshold is calibrated similarly, an external voltage is applied between VC5 and VC4A equal to the desired CUV threshold. Next, while in CONFIG_UPDATE mode, the CAL_CUV() subcommand is sent by the host, which causes the BQ76922 device to perform a search for the appropriate calibration coefficients to realize a CUV threshold at or close to the applied voltage level. When this search is completed, the resulting calibration coefficient is returned by the subcommand and automatically written into the appropriate configuration parameter. For more information on calibration, refer to the BQ76922 Technical Reference Manual.