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TM4C1294NCPDT: TM4C1294NCPDT - problems at 95% humidity

Bob Bacon
Genius 10815 points
Part Number: TM4C1294NCPDT


Hello
My customer is siing problems with the TM4C1294NCPDT as soon as the environment gets close to 95% humidity.

Then either the CANBUS interface drops out or the status LED (connect to pin 63) connected stops pulsing as it was previously. Although they can still communicate via the UART at this temperature.

Do you know of any known issues or problems that might cause this ?

 

They also ask if we could indicate why the MSL is only up to 60% RH? Is there a reason it was tested to a higher level?

Best Regards

Bob Bacon

  • 0
    TI__Guru**** 191906 points
    Hi Bob,
    Are you doing some type of JEDEC humidity biased stress test?
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Charles - is it not possible (even likely) that such findings are, "board issues" and not (entirely) MCU based? Is it not probable that board assembly, type/style of solder flux (and its residue), and "lack" of encapsulants - all may render the "board" at risk - under such conditions.

    Never/ever do posters (even vendor posters) list the "number of such units" which repeat the issue - which surely deserves mention.    (i.e. prevents "over-exercise" in the correction of (dreaded) "single-board anomaly!")

  • 0 in reply to cb1_mobile
    TI__Guru**** 191906 points
    Hi cb1,

    Thank you for asking the poster the questions that I was supposed to ask in the first place. This is the first time I have comed across a MCU and/or board failure due to high humidity. In the datasheet we don't specify humidity as a parameter. I'm just wondering if the test was under a real application environment or performed for humidity biased stress test according to AEC-Q100 for which the TM4C is not qualified.
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Thank you as well, Charles.

    We must note too that while "CANBus - or its Led monitor" appear "disturbed" - the MCU's UART continues to perform. Thus the MCU has appeared to "continue its function" - and the likelihood of condensation intruding upon critical pins/signal paths - rises even higher!

    Silent is the "testing & report" of the CAN transceiver (under such conditions) - that's of great interest as well - yet the MCU (alone) has received scrutiny.    (I resisted "witch-hunt" in description)

    And of course - the number of boards "presenting" this issue - even after request - remains unknown...