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BQ27742-G1: BQ27742 is in SEAL state and unable to UNSEAL

Part Number: BQ27742-G1
Other Parts Discussed in Thread: BQSTUDIO,

Hi,

We are using BQ27742, when I tried to program .df.fs file through micro controller, it got successful every time I tried.

while programming again, my power supply got interrupted. At this point I'm unable to program through micro controller. Then with the help of BQ Studio, I have programmed the srec file and got successful.

After that I'm able to program it through microcontroller.

But next time when the same issue came, I'm not even able to program through BQ Studio. BQ27742 is not entering into ROM mode and also not even getting UNSEAL when I'm trying with BQ Studio.

When I try to open BQStudio, it is showing this warning message some times not regularly.

I have selected OK to continue. 

then I made the auto refresh to OFF and tried to UNSEAL the device, but got unsuccessful in doing that.

Here I observed that both the FAS and SS bits of the Control Status register are stil in HIGH state.

Can you help me in recovering the device.

Thank You,

Sudheer

  • Hello Sudheer,

    Take care to ensure uninterrupted power during programming .df.fs or srec files. Even though all precautions are taken to ensure that recovery is possible during power loss while programming, there are conditions that result in bricking the product. This is because corrupt memory can cause unexpected execution and random writes. Until you can get the part to go back to programming mode, it is not recoverable.

    Try programming the srec again (a few times) using bqStudio to attempt to recover. The register values that are being currently read out are corrupted and therefore we cannot be sure that the part is sealed.

  • Hi Shirish,

    Thanks for your reply.

    I have tried programming the srec file using bqstudio several times after that, but still unable to recover.

    my observation is that device is not giving acknowledge for ROM mode Address.

    Also when unseal command is sent, I'm receiving Acknowledgement.

    Same with bqstudio also.

    when programming through bqstudio, it is trying to communicate with the device using ROM mode address but not receiving ack. As the acknowledge is not coming bqstudio is terminating the programming operation and sending error.

    Thanks,

    Sudheer

  • Hello Sudheer,

    Based on the description it looks like the bq27742-G1 is bricked. You will need to replace it.

    The screenshot also shows values that are not normal. This is consistent with data corruption.