JAJSCB2K April 2020 – July 2020 BQ77904 , BQ77905
PRODUCTION DATA
An OW fault detection is when at least one of the cell voltages is measured below the OW threshold, VOW. Both CHG and DSG are turned off if the fault condition lasts for a duration of OW Delay, tOWn_DELAY. The OW fault recovers when the cell voltage in fault is above the OW threshold + OW hysteresis, VOW_HYS for a time of OW Delay.
The tOWn_DELAY time starts when voltage at a given cell is detected below the VOW threshold and is not from the time that the actual event of open wire occurs. During an open-wire event, it is common that the device detects an undervoltage and/or overvoltage fault before detecting an open-wire fault. This may happen due to the differences in fault thresholds, fault delays, and the VCx pin filter capacitor values. To ensure both CHG and DSG return to normal operation mode, the OW, OV, and UV faults recovery conditions must be met.