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bq20z65EVM CHGFET and DSGFET Quick Question

Nicholas Alunni
Prodigy 170 points
Other Parts Discussed in Thread: BQ20Z65

Hello,

I noticed that when I'm discharging through the EVM the CHGFET and DSGFET are on, when I thought it would be just the DSGFET.

I noticed that when I'm charging through the EVM the CHGFET and DSGFET are on, when I thought it would be just the CHGFET.

Can someone please explain or point me to a document that explains why both FETs are on at both times?  Is this normal operation?  Is there ever a time when only one FET should be on or both FETs should be on?

Thanks,

Nick

  • 0
    TI__Intellectual 930 points

    At default, CHGFET and DSGFET are both on.

    The board can be configured so that when you are in fully charged state, the CHGFET will turn off and when you are in fully discharged state, the DSGFET will turn off.

    Regards,

    Viktoriya

  • 0 in reply to Viktoriya Sherman
    Prodigy 170 points

    Hello,

    I found a parameter under Config B that allows me to set a bit that will turn off the CHGFET once the [TCA] alarm is set or when the device realizes that it should terminate charging. 

    I cannot find a similar bit or config to tell the device to turn off the DSGFET once the [TDA] or [FD] flags are set.  I've looked through the dataflash 2 or 3 times as well as the manual 2 or 3 times and I appear to be at a loss of concrete evidence of how to get the DSGFET to turn off automatically.  Could you please let me know how to do this or point me to the specific section (for the bq20z65) that allows for this operation?

    Thanks,

    Nick

  • 0 in reply to Nicholas Alunni
    TI__Intellectual 930 points

    The DSGFET will only turn off if safety or shutdown conditions are triggered.

    Regards,

    Viktoriya