Most of the time the BQ25120 in our custom design works as expected. Sometimes, register 0 STAT_0/1 = FAULT, so I write RESET to register 9.
RESET does appear to reset the BQ because registers return to their default state, but the FAULT state persists. None of the registers show any faults:
* register 2 TS_FAULT0/1 = 00, TS_FAULT_OPEN = 0
* register 1 = 0
* register 0 TIMER = 0
VIN is valid and everything looks correct except for the FAULT. If I remove the battery and VIN, and reconnect the battery, the BQ returns to normal state. i2c register RESET does not. I do not have access to the MR pin so I was not able to try hardware reset.
On a second somewhat related note (but not directly related to the problem), I set VIN_UV_M = 1. The documentation is not clear here but if I understand correctly this will still set register 1 VIN_UV, but this will not set register 0 FAULT. Is that correct? Also, if I set VIN_UV_M = 1 after VIN_UV caused a fault, then register 0 FAULT should be cleared correct?