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Chip latches up and stops I2C communication (SCL internally stuck low)

user4428513
Prodigy 45 points
Other Parts Discussed in Thread: BQSTUDIO, BQ34Z100-G1

I am using the BQ34Z100-G1 chip with BQStudio and EV2300.  After talking I2C for some time the chip latches up and stops talking.  The only clue is the SCL seems to be pulled down internally and outputting 1.6V-2.2V.  After a day or so of no power the chip is reset and works again for a bit of time. 

What could cause the latchup? How can the chip be discharged/reset?

  • 0
    TI__Guru 73830 points
    Could you provide more information on talking I2C? Are you scanning continuously? If so, at what rate? Is there a charge or discharge current or voltage change in process over this period of time? When you say that no power to the chip will fix the problem, do you mean that you removed the REGIN voltage? You can power-up reset the device by removing voltage to REGIN or applying a temporary short from REG25 to VSS.
  • 0 in reply to ThomasCosby
    Prodigy 45 points
    We are scanning continuously during discharge. Refreshing register reads every regularly in bqstudio. Discharging at 980mA.
    Eventually the chip stops taking. Initially we thought the chips were dead...but after 24hours or so without batt+ applied it can be read again. So not dead ....but not a solution we can live with for a product solution.

    We have 10K pull-ups on SCL and SDA and using 3.2Volt logic on EV2300
    Could there be something in the voltage levels of the reference design that would cause this outcome?
  • 0 in reply to ThomasCosby
    Prodigy 45 points
    The power-up reset of REGIN or short of REG25 to VSS does not appear to be working to revive the chip
  • 0 in reply to user4428513
    TI__Guru 73830 points
    Shorting REG25 to VSS will reset the device and release it from a hung condition, so something else must be causing the clock to be held low. Was the clock still held low after resetting the device. Can you collect a log file where it is working and then quits working? That may provide a clue.