BQ76930: The BQ76930 charge issue

Zhang Liang

Part Number: BQ76930
Other Parts Discussed in Thread: BQ76942

Hi,

We use the BQ76930 for the battery charge, and now, our end customer feedback us there are some battery are about 0V voltage,

We analyse our design, and we find our MCU is damaged but the BQ76930 is still battery balanced because the MCU can't control the equalization circuit,

So the battery is always balanced discharge for a long time, that the battery discharge to 0V;

Please review below our request:

1. We want to disable AFE through hardware, so that when LDO loses power, BQ76930 can also be turned off.

2. We know how to design control circuits, but we don't know how to turn off BQ76930 in any way.

BTW, we try to power off the REGSRC(input source for output LDO), it only close the LDO of BQ76930 but it can't solve this issue, thanks.

over 1 year ago

0 Max Verboncoeur over 1 year ago

TI__Mastermind 25605 points

Hi Zhang,

I found this old thread that discusses a similar situation: BQ76940: BQ76940 balancing during fault - Power management forum - Power management - TI E2E support forums.

The only good way to disable cell balancing without an MCU command would be to reset the AFE.

The only real safe way to do this is to disconnect all of the cells from the AFE. Just forcing the supply low could cause damage to the AFE.

I recommend taking a look at the BQ76942. This is an updated version of the BQ76930 that includes a host watchdog to automatically stop cell balancing if the MCU does not issue a command for a programmable amount of time.

Regards,

Max Verboncoeur