• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 65 subscribers
  • Views 88 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ78350-R1: Losing communication during CHG and cycling off

Matthew Wilson
Prodigy 10 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ78350, BQSTUDIO

Tool/software:

Hello,

We are using four independent BQ78350 chips and are experiencing an issue with one of them.  The board works fine when it is in DSG mode or not doing anything.  However, when we attempt to charge it will cycle CHG on and off approximately every half second, with no end.  We have it loaded with the same BQStudio parameters as the other boards, and outside of OCC and OCD none of our safety parameters have a recovery of half a second (they are at least 2s.  It's difficult to catch any particular register issue on BQStudio, but we will usually see entire rows go blank.  We have also seen an error saying "no acknowledgement from device" and also something to the effect of "The sampling rate of (1443ms) has exceeded the allowed sampling rate)."  At one point I turned off all protections and still saw the same behavior.  

Is there some reason that the B78350 would lose communication only during charge?

Note: The battery pack is actually at 75% charge.  The board insists it is at 0%, or 8% after a reset.  We are obviously unable to make the chip count couloumbs high.  

  • 0
    Prodigy 10 points

    For additional information, we just took a scope to the SDA/SCL lines between the B78350 and the B93000 AFE.  When not charging we observer normal communications. When charging, we see only a repeating address/request word about every 100ms.  The clock does not appear to change.  

    In addition, this happens even if I am not using BQStudio.  

  • 0
    TI__Mastermind 25075 points

    Hello Matthew,


    This question has been assigned within the team and we will get back to you

    Regard,
    Alan

  • 0 in reply to Matthew Wilson
    TI__Mastermind 27321 points

    Hello Matthew,

    It is an strange behavior.

    Question, how fast are you sampling? 
    Are you using Evaluation board?

    The BQ78350 does not control the FETs, it will be the BQ769x0 AFE instead. 
    If you are losing comms and CHG FET is toggling, I would assume the GND return path to BQ78350 is breaking somehow to the point it prevents communication. 

    Please share your schematic if using a custom board. Does this behavior happen in TI evaluation board?