BQ20z95 SOV flag raised issue.
1. Duplication conditions as below diagram;
² Pins PRES/PACK+ of BQ20z95 Battery connect with NB PCM.
² Measured PACK+/PRES waveform as below;
Figure showed CH2 is PRES, CH3 is PACK+.
Pin PRES waveform is almost as same as PACK+ waveform.
2. Measured NB PCM connector’s resistance by DM;
Table showed each pin resistance.
3. Did shorting between pin PACK+ and PRES of battery pack;
Figure showed CH2 is PRES, CH3 is PACK+.
Pin PRES waveform is equal to PACK+ waveform.
4. Did testing to connect pin PACK+ and PRES by different resistor value;
Table showed result is OK that PACK+ not output.
Result is failed that PACK+ output voltage.
Figure showed item 4 testing diagram.
5. Power supply output 7V/10V contact with pin PRES of BAT;
² Did logging data by EVSW and created curve as below;
Figure showed bq20z95 reported abnormal higher voltage when 7V contacting with PRES.
Figure showed bq20z95 reported abnormal higher voltage when 10V contacting with
PRES.
Summary:
When only connecting pin PACK+/PRES of BAT with NB board, NB circuit cause PRES be pulled low. BQ20z95 PACK+ output high voltage through NB circuit to contact pin PRES. Gauge reports abnormal high error voltage affected SOV flag raise.
