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LMH1297: Device no longer accessible through SMBus/I2C

Sebastian Helbing
Prodigy 150 points
Part Number: LMH1297
Other Parts Discussed in Thread: USB2ANY

Greetings,

we are currently experimenting with the LMH1297. We use the eval kit as well as a selfmade design. We managed to find a fitting configuration with the kit and SigCon Architect. Our SW engineer took the complete register settings (saved with SigCon Architect) and tried to transfer it to the LMH1297 on our board. Unfortunately he wrote the complete set, including the reserved registers (however, exactly the same values, that have been read out from a working LMH1297).

This did not work as intended and as a consequence, the chip on our board is no longer responding at all, even after a power cycle. We tried all possible I2C adresses without success. The chip seems to be dead.

I know, that writing to reserved registers is not the best idea and we cannot blame TI for that :-) ... however, as an engineer, I'd like to understand, what might have happened and whether there is a chance to "repair" the device.

If not, I can and will exhange the IC on the board.

Best Regards,

Sebastian

  • +1
    TI__Guru* 91760 points

    Hi Sebastian,

    As you noted, you have powered off and on and device still is not responding to the SMBus commands. Somehow device got damaged. I am assuming you have tried different SMBus addresses and device is not still responding. Is the device drawing normal amount of current comparing to a regular part?

    Regards,Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 150 points

    Hi Nasser,

    thank you for the reply!

    Some miracle happened. Today I wanted to redo the test with all SMBus addresses again in order to give you a thorough answer ... and I noticed, that the device is answering again on its dedicated address and works as intended. It responds again to the FPGA on the board, as well as to the attached USB2ANY (taken from the Eval Kit). Really strange! Usually I do not believe in self-healing of electronics, thus my only explanation is, that the boards sat a few days compeletely unpowered and all charge vanished. Probably a quick OFF/ON power cycle did not resolve the internal confusion.

    For me the issue is resolved.

    Best Regards,

    Sebastian