BQ40z50 opens charge FET on charge termination even though CHGIN bit is zero.

Deckerg

Other Parts Discussed in Thread: BQ40Z50I'm working with the BQ40z50 guage, and I want the charge FETS to remain on even when the pack is at 100% charge. According to the technical reference manual, setting CHGIN in Fet Options to zero will keep the FETs on after Valid Charge Termination, but my pack already has the CHGIN bit set to zero and the pack still turns off when charge terminates.

over 10 years ago

0 Swaminathan Ramanathan75031 over 10 years ago

TI__Expert 6575 points

What is the value of the FET Options[CHGFET]? Please make sure this is also 0. This will have a bigger impact on the FET staying on.

0 Deckerg over 10 years ago in reply to Swaminathan Ramanathan75031

Intellectual 685 points

ChgFet is also zero.

0 Deckerg over 10 years ago in reply to Deckerg

Intellectual 685 points

Any other thoughts? A appear to have all bits set correctly to keep the FETs open, but they turn off when the packs reach full charge.

0 Invalid User :-) over 10 years ago in reply to Deckerg

Intellectual 755 points

I have seen this happen with other bq parts when the TCA bit was set.

0 Deckerg over 10 years ago in reply to Invalid User :-)

Intellectual 685 points

The TCA bit is a flag that is set by the 40z50, not a configuration bit to set. Is there a way to disable the TCA while still letting the pack fully charge?

0 Invalid User :-) over 10 years ago in reply to Deckerg

Intellectual 755 points

I haven't used the 40z50 but there should be a way to control when the TCA flag is set and what actions happen.

Power management

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BQ40z50 opens charge FET on charge termination even though CHGIN bit is zero.