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Clearing PFIN flag

Srivatsa Raghunath
Prodigy 180 points
Other Parts Discussed in Thread: BQ20Z90

Hi,

 

How do we clear the PFIN flag in bq20z90 used for a four cell gauging application? We're unable to reset the PFIN timeout to 0 sec as the PFIN flag is already set not allowing write operation in DF

Thanks and regards,

Srivatsa

  • 0
    TI__Expert 6860 points

    Hello Srivatsa,

    The procedure for clearing a permanent failure is located in the Quick-Start Guide for bq20zxx Family Gas Gauges http://www.ti.com/litv/pdf/slua421a  section 8.2, page 15.

    Best regards, Keith

     

  • 0 in reply to Keith Keller
    TI__Prodigy 180 points

    Keith,

    I believe the method mentioned in the app note does not work when the PFIN flag is set.  I've tried this and it was not successful

    Regards,

    Srivatsa

  • 0 in reply to Srivatsa Raghunath
    TI__Expert 6860 points

    Hi Srivatsa,

    It's necessary to remove the fault and have the device unsealed to send this command.

    There isn't anything special about clearing PFIN or any of the others.

    Can you read the dataflash parameters?  If so, you're unsealed.

    Best regards, Keith

     

  • 0 in reply to Keith Keller
    Intellectual 280 points

    Keith (or whomever sees,this, I know this thread is obsolete), I am having this problem as well.  The designer left ~PFIN floating and it reads low with my DMM.  I made a mistake and changed the PFIN Detect Time to non-zero which immediately set the PFIN flag.  Can I clear the fault by pulling ~PFIN high, then writing the Permanent Failure Clear key?

    Ed K

  • 0 in reply to ed kornegay
    TI__Intellectual 2650 points

    Ed ,

    I think that should work and I can't think of anything to loose by trying?  You certainly won't be able to clear it if you don't remove the source of the fault (ie floating pin) before sending the PFCLEAR KEY and I am not aware of anything else that would prevent clearing it. Let me know and if it does not work I'll try to recreate the fault and find what does work. What gauge are you using ?

    Mike

  • 0 in reply to Mike Ewer
    Intellectual 280 points

    Well I did try it, and.... it worked!  Used a 1/8W 15k resistor to pull it up to 5V and had a co-worker run the software.  I first applied the pull-up, cleared the flag, then released the pull-up.  The flag came back.  Next time I applied the pull-up, cleared the flag, set the timer back to 0, then released the pull-up - no flag.  Works good.  That goes in the bag of tricks.

    Thanks