The BQ76942 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 VC10 and VC9 that is equal to the desired COV threshold. Next, the CAL_COV() subcommand is sent by the host, which causes the BQ76942 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 the Protections:COV:COV Threshold Override 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 VC10 and VC9 equal to the desired CUV threshold. Next, while in CONFIG_UPDATE mode, the CAL_CUV() subcommand is sent by the host, which causes the BQ76942 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 Protections:CUV:CUV Threshold Override configuration parameter.