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BQ25628: Random reset when I2C communication happens

Marco De Donno
Prodigy 10 points
Part Number: BQ25628

Tool/software:

Hello,

on our board I've noticed that the BQ25628 causes power drops and resets the system. Using the oscilloscope I can see it happens when there is communication over I2C.




On our board there is also a Temperature sensor on the same I2C bus and current consumption is always below 5mA.

This is what I've tried so far but reset still happens:
- Reduce I2C speed to 50kHz
- Increased time between 2 Start commands in case of NACK to 1ms
- Communication only with BQ25628 (100khz and 50kHz)
- Communication only with temperature sensor (100khz and 50kHz)
- Disable watchdog 

When reset happens and reading the IC registers the last bit of CHARGER_FLAG_0 is 1, so WD timer signal rising edge detected. It happens also if WD is disabled.
Is this normal?

Then I've just disabled the communication over I2C (except at startup) and no reset happened.

Is there something else I can try?

  • 0
    TI__Mastermind 31550 points

    Hi Marco, 

    Thank you for reaching out via E2E. Can you please help to share the top markings of the BQ25628 IC in question where you see this behavior? 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Prodigy 10 points

    Hello Garrett,

    here the top marking of the IC

    Kind regards,

    Marco

  • +1 in reply to Marco De Donno
    TI__Mastermind 31550 points

    Hi Marco, 

    Thank you for providing the top marking it does help to explain the behavior you are observing. Please allow me to explain further below. 

    There was an issue identified on this device where when in battery only operation I2C communication can lead to the loss of VSYS you observe. To avoid this behavior the timing requirements related to I2C communication listed in datasheet section 8.5.1 must be followed.

    Additionally there were a small percentage of units which would still show the loss of VSYS behavior even when timing requirement was followed. To address this TI issued a product change (PCN) in February 2024 and all impacted customers were notified. All ICs released after this date will function without issue when timing requirement is followed.

    The top markings provided confirm the IC you are using was manufactured pre this date and based on your report is likely one of the small percentage of units described above. Given this my best recommendation is to swap out this particular unit with a new BQ25628 IC. All ICs ordered through TI.com will be manufactured post the product change. I apologize for this inconvenience. 

    Best Regards,

    Garrett