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DK-TM4C129X: boards fail with apparent processor failures

Part Number: DK-TM4C129X

hi team, kindly help on below issue.

I've been working with a TM4C129x development board which we are very pleased with. However we have now had two boards fail with apparent processor failures.

 

The symptom is that the 3.3V LED turns off.Further investigation suggests the LDO regulator goes into current limit mode and that the processor is drawing in excess of 200 mA (measured using the current sense resistor accessed using J14).

 

When the first board failed we just assumed we had zapped it at some point with ESD. However I have since installed a static dissipative work surface and wear a ESD wrist strap so I very much doubt that is the issue with the second board.

 

I have external electronics attached through the booster pack 1 header using I2C, GPIO and ADC. The I2C and GPIO signals are buffered through appropriate level shifters. The ADC input is connected through a 10K resistor to an output that has a 0V - 3.6V maximum range. The external electronics is different for the second evaluation board than it was for the first.

 

I can't identify any specific action that may have caused the failure in either case. Neither failure occurred while I was actively working with the board, although in both cases it was powered on and running.

 

Googling turns up a couple of articles (https://e2e.ti.com/support/microcontrollers/other/f/908/t/566893 and https://e2e.ti.com/support/microcontrollers/other/f/908/p/435224/1558665) which look like the same issue, but no resolution is reached in either thread.

 

Any suggestion as to my next steps? We need to understand this issue to ensure we aren't baking a major problem into the hardware we are developing and to avoid both delay and expense while we develop our system!

  • Hello Ken,

    This is a difficult request to offer much value on given what is presented. This kind of failure isn't common on our devices, so general debug methods are really all we can offer here.

    From the description, it sounds like they confirmed the MCU itself has been damaged if it's drawing excessive current when isolated, so then the question becomes what damaged it. If ESD is ruled out, then some sort of overvoltage or overcurrent from an attached device would explain the issue.

    There isn't anything elaborated as to what these additional devices are though, so I really wouldn't know where to start in terms of suggesting what may be a possible source of the issue. It sounds like there are a lot of precautions being taken, but I just don't know enough to offer theories on that front.

    Also they mention the devices attached differed between the two failures, are there any similar devices, or at least similar use cases?

    The only other comment I can make is they should investigate if they may have caused the errata GPIO#09 issue to arise: www.ti.com/.../spmz850g.pdf

    As an aside, the referenced threads went cold after the customers posting did not return back with feedback about some debug ideas. For example in one thread Amit suggested to remove the various added 3.3V devices to try and isolate which caused the failure, but that went with no reply from the customer... nothing we can do when customers go quiet.
  • Closing thread due to offline exchanges.