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BQ76952: Communication with no ACK and secondary protection

Francis Jiang
Intellectual 1770 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO

Hi Team,

The customer provides some devices that cannot communicate after OTP programming. The I2C waveform is shown below.

It can be seen that a NACK respond next to the address 0x10.

I exchange the device to our EVM. The result is red LED D3 turning on. According to the EVM Users' Guide, I think the FUSE or protector BQ771807DPJR are working. Also, the device cannot communicate with BQstudio on our EVM after exchanging.

I checked that various permanent fail(PF) will make the FUSE pin drive high, and it should be noticed that the Protection Configuration[PF_FUSEE] is disable in OPT programming according to customer.

Could you please give me some ideas to further debug this problem? In particular, please consider the situation that the secondary protection is working and communication with no ack. Thanks.

Best Regards

Francis Jiang

  • +1
    TI__Genius 11315 points

    Hey Francis,

    If the device cannot communicate with BQ Studio after being put onto our EVM (assuming the EVM was functional beforehand), then it is safe to assume that the device became damaged in some way, possibly during OTP programming. Have you tried putting a new device on the customers board to see if anything happens?

    Thanks,
    Caleb

  • 0 in reply to Caleb Perez
    TI__Intellectual 1770 points

    Hi Caleb,

    What situation does the device loss communication with host controller? As address and type of communication have been verified.

    Any protections can cause this phenomenon?

    Best regards

    Francis Jiang

  • +1 in reply to Francis Jiang
    TI__Guru* 79863 points

    Hi Francis,

    Which registers were programmed in OTP? Has the Comm Type been changed? A list of the registers that were programmed would be helpful in debugging the issue. None of the protections should impact the communications with the IC.

    Regards,

    Matt