Other Parts Discussed in Thread: BQ79616
Tool/software:
We have experienced an odd and so far unexplainable failure with one of our production Satellite BMS boards utilizing the Ti BQ79616 chip. The failure appears to be related to the power reuglation circuit and specifically the capacitor C302 in the attached schematic. There was no notable event when the failure occured. The board was in a shutdown state and had been sitting idle for several weeks. When the system was started up, this board failed to communicate and the decision was made to remove the battery from the vehicle in question. Upon inspection, the board was noticeably hot even in its shutdown state. The power regulator was reading 13-14 degrees with an infrared thermometer and the capacitor was measuring over 200 degrees. The input voltage to the regulator was 64V and the output was 3.85V. Unplugging the battery stack from the board and re-plugging it in had no affect. The chips immediately started to heat up again. The components are not under spec'd and this seems to be the only failure of this kind we have had. Are there any known reasons why this could happen or may have happened? Any input would be appreciated.
Here are the part numbers for the power regulation circuit components:
| Ref | Description | MPN |
| C302 | CAP, CERM, 1uF, 100V, +/- 10%, X7R, 1210 | C1210X105K101T |
| Q301 | TRANS NPN 150V 1A TO252 | ZXTN4004KTC |
| R317 | RES, 200 OHM, 1%, 2010, SMD | RMCP2010FT200R |
| R318 | RES, 100 OHM, 1%, 2010, SMD | RMCP2010FT100R |
