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BQ78350-R1: Help required for SM Bus communication problem

Vatsal Shah
Prodigy 125 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQSTUDIO, TIDA-00792, BQ78350, BQ76940,

Dear TI Engineer,

We are evaluating TIDA-00792 design and facing issues with SM bus communication through bqStudio. We have bq76940006 mounted on board as AFE device & . The GUI connects and disconnects at fixed interval of around 2 seconds. It shows an error 'No acknowledge from device'. GUI has inconsistency with data read-write with an error 'MAC command sent does not match with MAC returned in read packet'

How do we configure / set the AFE I2C address (0x18) for communication with bq78350.

Does the AFE device's LDO output voltage or CRC makes any incompatibility with either bq78350 or bq78350r1?

Looking for support.

Thank You.

Vatsal

  • 0
    TI__Guru 54715 points
    Hi Vatsal,
    The (bq78350 or) bq78350-R1 should be used with the 2.5V and address 0x08 version of the bq76940, see the bottom paragraph in section 1 page 10 of the technical reference manual.
    You note the (AFE) monitor is bq7694006, this is a 3.3V part with address 0x18. If you are operating the bq78350-R1 from the bq76940 REGOUT the voltage will exceed the 2.75V abs max of the VCC and the part may be damaged.
    The communication drop out is most likely due to the I2C address. The bq78350-R1 uses address 0x08 to communicate to the monitor. Communication with the monitor is essential to operation and a high priority. If it does not find the monitor it will spend most of its timeline trying to establish communications with the monitor and SMBus communication will be disrupted.
    The bq7694006 versions are available for designers who use their own MCU and need a different address. Install a correct version of the monitor and the board should talk. If the bq78350-R1 has been overstressed it should be replaced also.