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Likelyhood of blowing CMOS chips by applying reverse polarity???

Discussion in 'Electronic Basics' started by royalmp2001, Sep 3, 2005.

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  1. royalmp2001

    royalmp2001 Guest

    What are the chances of detroying a CD4069 or a 7555 by applying the
    power with reversed polarity.
    Anyone destroyed such a device this way??
     
  2. John Larkin

    John Larkin Guest

    Assuming a non-wimpy power supply, 100%.
    That, and lots of other ways.

    John
     
  3. Pi

    Pi Guest

    Usually testing has next steps:

    1 move as far away from the electronics as possible
    2 turn on the power
    3 do you see the light (!) ? If so, the test failed, stop it.
    4 wait a minute
    5 do you se smoke ? If so, the test failed, stop it.
    6 do you smell anything? If so, the test failed, stop it.
    7 wait a minute, then touch the eletronics, espacially the power parts
    8 did you burn your fingers? If so, the test failed, stop it.
    9:
    You reached the end of the test. Does it actually work? If so, keep
    your mouth shut to the commercial people in your company and make all
    neccesary improvements before they claim the project to be finished
    and make a product from your first test setup.

    Pieter
     
  4. Don Bruder

    Don Bruder Guest

    Quite high - Perhaps not 100%, but close enough to it for practical
    purposes. I'm sure hundreds, if not thousands, of electronics tinkerers
    have blown up chips (CMOS or otherwise) this way.
     
  5. PeteS

    PeteS Guest

    It's not just tinkerers that blow up chips that way - I have had new
    units go to production (first ever run) and had parts in backwards.
    With the power at corner pins, that meant the power was applied
    reversed.

    Fortunately, the burn marks on the PCB were not fatal to the unit
    (although the misplaced components had the magic smoke released).

    Cheers

    PeteS
     
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