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.