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pic16f819 fried pins

Discussion in 'Electronic Basics' started by BrunoG, Jan 10, 2006.

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  1. BrunoG

    BrunoG Guest


    A brand new pic16f819 fried under my eyes : it was running on my easypic2
    development board, with nothing else than leds on its outputs, when I saw
    the RB6 and RB7 leds dimming and then turning off. After that, I was unable
    to flash it again (RB6 and RB7 are the programming pins). And all others
    pins work well...

    This chip was brand new, has only a very few cycles of flash writes (a
    dozen), has never been loaded on its ouptuts, and my board runs perfectly
    well (I tried after that to flash and run some other pics of p16 & p18
    family without any problem).

    I fried by myself some pics, but I never saw a pic frying of its own 8-(

    As it is not 100% dead, I wonder if it is a defective chip or something

    Does anybody here did experiment the same issue ?

    Thanks !

  2. One 'comment', leaps out at me here. "Nothing else than LEDs on it's
    outputs". I hope there are some current limiting resistors as well?. If
    not, then the outputs will have been massively overloaded....

    Best Wishes
  3. BrunoG

    BrunoG Guest

    Yes sure, the easypic has its own limiting resistors on board
    I just mean : no extra load or extra device connected to the outputs...

    Thanks !

  4. Have you tried to remove and reinsert the chip sometimes the chips could
    latch up due to some extreme/unlucky condition?

    There will always be a failure rate of these chips maybe you were just
    unlucky and got a faulty chip :-(

  5. Rune Christensen wrote...
    Ahem. Did Bruno fail to tell us about a fully-charged 2.2uF 180V
    capacitor "coming from a nixie power supply" that he discharged into
    the RB7 pin and its associated '4053 cmos switch IC? "Nothing else
    than LEDs on it's outputs," he says... Ahem.
  6. BrunoG

    BrunoG Guest

  7. BrunoG

    BrunoG Guest

    Yes I did, but without success. The pic seems to be lachted up as you say,
    because it still runs, but RB6 & RB7 are inoperent...

  8. Stef Mientki

    Stef Mientki Guest

    How foolish this may sound, try it tomorrow again!!
    Me and someone else have seen such a phenomena,
    when programming the chip with a "not-so-good" programmer.
    And let me hear if you are the third person !!

    Stef Mientki
  9. BrunoG

    BrunoG Guest

    Hi Stef, I give the pic a little bit rest and and will try later as you say
    : I'll tell you tomorrow more about its health...
    I never, ever, had any problem to write a pic with the easypic board !
    That's why I'm so surprised, I wrote pics thousand of times.
    Maybe some software or fuses configuration may have cause this kind of
    problem to other people ?

    Thanks !

  10. Pooh Bear

    Pooh Bear Guest

    When micros get slightly 'hurt' they often lose the ability to be re-programmed.

  11. Ian Stirling

    Ian Stirling Guest

    Are you very sure you always observed proper anti-static precautions?
    Very, very odd stuff happens when static hits chips, it can cause odd
    delayed failures.
  12. No, the OP said, "leds on its outputs", and didn't introduce the
    extraneous apostrophe.

    One demerit assessed.
  13. BrunoG wrote...
    What was your charged 2.2uF 180V capacitor doing this time around?
  14. BrunoG

    BrunoG Guest

    GOOD Ian, I think you got it.

    The only difference between the defective pic and the other ones, is that I
    bought it to my local dealer's store, instead of getting it directly by post
    delivery from my usual supplier. Of course it increases static hits
    exposures due to extra handling.

    Thanks !

  15. Someone

    Someone Guest

    waiting to zap another day? hehehe!
  16. BrunoG wrote...
    That's a 150pF capacitor charged to say 3kV, compared to your 2.2uF
    capacitor charged to 2.2uF 180V. :) The first has 0.7mJ of energy,
    compared to 35mJ for the second. But 0.7mJ is more than enough.

    It only takes one small spark, which you may have administered.
  17. BrunoG

    BrunoG Guest

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