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BQ33100: CFET is OFF when system is powered keeping caps from charging

Andrew Trill
Prodigy 20 points
Part Number: BQ33100

For over a year i haven't had an issue with this product.  Now for some reason when i discharge the system and re-apply power to charge the super caps, my CFET signal is HIGH on the Pchannel Gate meaning my caps are not charging.  Is anyone aware of how this had happened?  Is there a setting i accidentally turned on that does this?  I was checking for a bad PFET by issuing the 46 command with 0x0000=OFF, 0x0004=ON commands to test the FET.  I replaced the FET and now have this issue. 

I can explain more or better if this issue is misunderstood.  

  • 0
    TI__Mastermind 25955 points
    Hi Andrew,

    Please check your ESR values to see if they are negative. If so, please try reissuing the learn command so the monitor will relearn the capacitance and ESR values.

    If this does not resolve the issue, please upload your .SENC file and a log of the event. A device schematic and layout marked up with which components were replaced and where may also be helpful.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 20 points

    Bryan, 

    So i downloaded an older SENC file to the board and it started working fine again.  As that worked i believe with this board i never loaded a SENC file to it at start up.  Possibly the pchannel charging FET was damaged from the get go and luck had it that my charging voltage and ROM value charging voltage were equal so it looked like the charging fet was shutting off the current flow but really it was just the caps met the charging voltage.  When i did first power up the new board i did upload a gg file though thinking that worked.

    My question is, does every board need to be programmed with a SENC file before it works properly and uploading a GG file is not the same as it doesn't access all parts of ROM?

    I did grab the SENC file off of the non functioning board before programming the old version that got it working if you would like to look at it. 

    Either way i got it working and thank you for mentioning the SENC file to job my memory to look at that. 

  • 0 in reply to Andrew Trill
    TI__Mastermind 25955 points
    Hi Andrew,

    I'm glad to hear it is working! Thank you for the discussion on how you were able to achieve the results.

    Sincerely,
    Bryan Kahler