• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 1659 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ76940: BQ76940 I2C stuck communication to microcontroller , how to reset stucked Fronted AFE

Michael Hutmacher
Prodigy 55 points
Part Number: BQ76940

hi all.

We build a battery 14S  with BQ7694000DBT which is communicating with a microcontroller over I2C.

Under normal working conditions everything works fine as expected.

The complete battery is mounted in a closed metal housing, and is working in  a harsh enviroment .

One part of  testing in the application , is to do HF Ignitions with sereveral KV on the Metal Housing.

This brings sometimes the I2C communication between uC and AFE to get stucked.  The SDA,SCL, Alert line are held down  by BQ AFE

Unfortunately we found no way to reset the AFE, without removing all connections to the cells.

We tried already  removing voltage REGSRC or shorting voltages REGOUT, BAT,VC10X, VC5X.

Only removing the connector to the cells, waiting until all caps are dischred and reconnecting helps.

We are searching for a solution how to  reset a stucked Frontend by microcontroller.

Any Advice ?

  • 0
    TI__Genius 10830 points
    Hi Michael,
    One of our BMS experts has been assigned to your issue and will answer shortly.

    Regards,
    David
  • 0 in reply to David Hien
    TI__Guru 54715 points
    Hi Michael,
    The bq76940 is a slave device, SCL is an input and does not drive the bus. If the I2C bus is stuck with SDA low the MCU should send up to 9 clocks so the slave releases the bus.
    RESET for the part is described as the supply voltage below VSHUT. It is hard to do with the cell monitor inputs and multiple power pins, but if you have done this you have reset the part. Taking REGSRC low would remove power from the I2C buffer circuitry as well as others and allow it to restart. If the part is clamping SCL low the ESD structure would be the likely candidate, remove the pull up voltage which would normally come from the REGOUT.
    Directing the transient energy away from the electronics is the best solution.