Other Parts Discussed in Thread: BQ78350, BQ76200,
Hi Team Members, My Li-ion battery pack design is 7S 10P, 34.5AH, 24V typical. My BMS uses BQ76930+ BQ78350+ BQ76200 for high side FET drive. The ALERT signal from BQ76930 is directly connected to ALERT pin of BQ78350, and there is a 499K ohm from this pin to ground. I am encountering ESD disruption at +/- 4KV or above that cuts off battery discharge and charge. Although battery charge/discharge recovers 5 seconds later, that's not acceptable in my battery application. Although I have plastic battery pack internally coated with conductive spray, ESD induced noise still cuts off normal battery discharge. I inspected the waveforms among ESD zapping trigger, ALERT, and the Discharge enable signal to BQ76200, and found occasionally there is ALERT pulse train with 0.25 sec period, and sometimes this ALERT signal lasted for 0.2 sec, but such sporadic pulse train on ALERT didn't result in Discharge Disable. Discharge is always disabled, for 5 seconds then recovers by itself, right at ESD current trigger which just lasts for 50 to 100 ns. Sometimes even if I was just ESD zapping to the battery's outside plastic case, no physical electrical connection to the whole battery pack at all, battery discharge is still cut off. This is very annoying to me. Really appreciated if anyone can help me out of the muddy trap. I have no idea which among the 5 conditions, UV, OCD, SCD, external ALERT, etc., was detected during ESD zapping that cuts off battery discharge, and how to verify the root cause.
