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Killing me softly — Parallax Forums

Killing me softly

g3cwig3cwi Posts: 262
edited 2012-03-18 17:49 in Propeller 1
The inevitable result of some agressive prototyping here was the application of 12 Volts to a prop pin. This only seems to have taken out the single pin - is that normal or am I just lucky?

Cheers

Richard

Comments

  • idbruceidbruce Posts: 6,197
    edited 2012-03-18 02:53
    g3cwi

    I truly do not have an accurate answer to your question, but I sure do like your phrase "agressive prototyping" to describe the cause :)

    I am just guessing, but I would imagine that is probably normal since it was just going to a pin. From what I have read in the forum, I assume the diode for that pin probably burned up, but saved the rest of the chip.


    Bruce
  • Mike GreenMike Green Posts: 23,101
    edited 2012-03-18 08:27
    It's partly normal and partly luck. As idbruce suggested, you've probably burnt out the protective diode between the I/O pin and the on-chip Vdd bus. The luck part is that running 12V into the Vdd bus will cause voltages to rise along the bus. Anything over about 4V will damage the rest of the chip. Probably the protective diode burnt out before this damage could occur.

    There are plenty of other I/O pins you can use. Enjoy your good fortune and watch those "high" voltages.
  • RaymanRayman Posts: 14,844
    edited 2012-03-18 17:12
    I've ruined a few chips this way... I've heard of just the pin going bad, but I don't remember if I've seen that or not.
    Usually, what I see is the PLL getting fried... You might want to double check that you can do something that requires the PLL...
  • turbosupraturbosupra Posts: 1,088
    edited 2012-03-18 17:49
    I've probably killed 1/2 a dozen single pins in my few short years with the prop. I would say this is normal (in my experience) in lower voltage cases, I don't know how it would turn out above 12/14 volts.


    g3cwi wrote: »
    The inevitable result of some agressive prototyping here was the application of 12 Volts to a prop pin. This only seems to have taken out the single pin - is that normal or am I just lucky?

    Cheers

    Richard
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