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BQ25120AEVM: Unreliable I2C communication

Ricardo Smith
Prodigy 40 points
Part Number: BQ25120AEVM
Other Parts Discussed in Thread: BQ25120A, EV2400,

Hello,

We are trying to evaluate the BQ25120A so that we may potentially use it in our product. However, while testing it, we have found that the I2C appears to stop working at what appears to be random periods of time. Observing this with a logic analyzer, the BQ25120A stops acknowledging our i2c requests. So far, we have found that disconnecting the battery from the BQ25120A is the only way to resolve this issue. Please let me know if you may be able to share any insight on what may be causing this.

Thank you,

-Ricardo

  • +1
    Prodigy 240 points

    Hi Ricardo,

    What are you using to communicate with the I2C on the EVM? Is it the EV2400 or something else? Can you send an oscilloscope plot of the two I2C lines? Does sending a reset to BQ25120A resolve the issue or is power cycling the only way to resolve the issue?

  • 0
    TI__Mastermind 18540 points

    Hi Ricardo,

    I have a few questions to gather more context and identify the cause of this behavior:

    - What voltage is the i2c pull up rail and what are the pull up resistor values?

    - I see that you are using a BQ25120AEVM, are you also using an EV2400 for communication?

    - Can you please provide waveforms of the NACK'ed I2C transaction?

    - With what frequency does this occur? Once it occurs the device stops acknowledging all communication?

    - You've mentioned that disconnecting the battery is the only resolution for this issue. Does it occur when VIN is present? In this state does asserting VIN allow I2C to resume normal operations? What is /CD connected to and what is it biased to in these circumstances?

    Best Regards,

    Juan Ospina