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g3cwi
03-18-2012, 09:06 AM
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

idbruce
03-18-2012, 10:53 AM
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 Green
03-18-2012, 04:27 PM
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.

Rayman
03-19-2012, 01:12 AM
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...

turbosupra
03-19-2012, 01:49 AM
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.




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