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BQ32000: RTC Ringing on VCC after 01 July 2020

Christopher Van Meter
Prodigy 30 points
Part Number: BQ32000

Team, 

We are having Issues with exceptional VCC "Ringing" after (01 July 2020, 00:00:00) 07:01:20:00:00:00 that did not exist prior to (30 June 2020, 23:59:59) 06:30:20:23:59:59, during a measurement of our device.  I have provided O-Scope images of VCC (Yellow) and VBACK(Blue) below.  What could be happening to the BIT allocation and power drain pre and post 01 July 2020 that could be driving VCC lower than the VBACK and Vref threshold post 01 July 2020 that did not exist Pre 01 July 2020?  We have been using this device since 2012 with no other issues.

We are checking our bypass caps to see if we can mitigate this hardware-wise.  

Any help would be appreciated,

Thanks, Chris

Pre 01 July 2020: 

Post 01 July 2020: 

  • 0
    TI__Mastermind 18070 points

    Hi,

    My coworker will get back to you the next business day.

    Regards,
    Hao

  • 0 in reply to Hao Z
    TI__Genius 16845 points

    Thanks for bringing this to our attention. Let me try to get a better understanding of the issue.

    This is my understanding, could you correct me if I'm wrong?

    • these RTC devices have been powered up and operating in the system for some extended period of time
    • since 16 days ago on July 1, the RTC has been suffering the exceptional VCC ringing
    • VCC ringing dips VCC low enough for switchover to VBACK

    Your images didn't upload. Could you try attaching them again?

    Kind regards,
    Lane 

  • 0 in reply to Lane Boyd
    Prodigy 30 points

    Lane. 

    Thank you.

    • these RTC devices have been powered up and operating in the system for some extended period of time 
      • (YES with battery backup, since 2012)
    • since 16 days ago on July 1, the RTC has been suffering the exceptional VCC ringing
      • (Yes, and then appears to exhibit a VBACK Switchover which locks up the I2C lines)

    • VCC ringing dips VCC low enough for switchover to VBACK
      • (Correct)

    If we reset our devices back to pre-01 July 2020, no incidents of I2C lockup nor VBACK Switchover. 

    However, as soon as the date 01 July 2020 passes, we exhibit failures almost immediately.

    Our current solution is to roll back the date/time.

    Here is an image with VCC (Yellow) and VBACK (Blue) during a measurement on our device under a date of pre- 01 July 2020.  We do see some ringing on the VCC line, but if we set the date to anything pre-01 July 2020, this is what we get.  These BQ320000 have been on our devices circa 2012.

    Here is an image with VCC (Yellow) and VBACK (Blue) during a measurement on our device under a date of post- 01 July 2020.  There is now significant ringing on the VCC line.  It appears now that the RTC goes into VBACK switchover as VCC falls to 2.6V which is below both VBACK and VREF.  I am not sure what is happening internally that would be providing this fluctuation precisely at 01 July 2020.

     Pictures also forwarded to Viktorija Cecil.

  • 0 in reply to Christopher Van Meter
    Prodigy 30 points

    Lane,

    Just to clarify, 

    I guess I would phrase it more like a question.  Would this ringing on VCC cause a switchover event?  We don't actually know if it is causing a switchover event but that is the best hypothesis we have at the moment for this post 01 July 2020 issue.
    thanks, 
    Chris
  • 0 in reply to Christopher Van Meter
    TI__Genius 16845 points

    Hi Chris,

    Thanks for the info. We're connected on email now, let's continue our discussion offline

    Kind regards,
    Lane