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SMBus vs I2C on BQ76940EVM

Michal Solecki
Intellectual 295 points
Other Parts Discussed in Thread: BQ76940EVM, BQ76940, BQ78350

Hi,

We are in the final stages of our design and we used the bq76940EVM for development and we are pretty sure of the answer, but we wanted to confirm our understanding.

After reading the datasheets and TRMs, it is said that the BQ78350 controls the BQ76940 through its I2C connection. But are there functions/features on the AFE that can only be controlled, modified or configured through the software provided by TI (i.e. we need access to the I2C pins to change some registers in the AFE because the BQ78350 can't handle that feature)?

We basically want to know whether we can remove the I2C connector in our final design.

Thank you in advance.

  • 0
    TI__Guru 54715 points

    Remove the I2C connector.  You may want test points for board test, but I2C must not be accessed in the system with the bq78350 running.

    I2C accesses to the registers may cause bus contention and communication errors.  The gauge will also check the registers periodically and overwrite any changes.

    AFE register and communication errors will be counted toward a permanent fail condition.  See the TRM sections 4.13 and 4.14