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'16C84 Sinks 2 Amps and Lives'
1996\05\23@083316 by Clyde Smith-Stubbs

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Some chips blow instantly if you reverse the power supply - not so the 16C84.
I accidentally (how else?) plugged one in backwards, and I happened to have
an ammeter in series with the power supply - 4 fresh AA size alkaline cells.

The ammeter read just over 2 amps - I stood there for about 5 seconds trying
to make sense of the reading before realizing what I had done. Pulled it out,
put it in the right way, and away it went!

--
Clyde Smith-Stubbs       | HI-TECH Software,       | Voice: +61 7 3300 5011
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1996\05\23@091625 by myke predko

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>Some chips blow instantly if you reverse the power supply - not so the 16C84.
>I accidentally (how else?) plugged one in backwards, and I happened to have
>an ammeter in series with the power supply - 4 fresh AA size alkaline cells.
>
>The ammeter read just over 2 amps - I stood there for about 5 seconds trying
>to make sense of the reading before realizing what I had done. Pulled it out,
>put it in the right way, and away it went!
>

Yah, I did the same thing a couple of nights ago, I use a ZIF socket for
prototyping and put the 'C84 in backwards.  Something was smoking, the power
supply's fuse went, but after putting in a fresh fuse, opening a window, I
tried the PIC again and no problems (including reprogramming it)!

Pretty tough little cookie!

Myke
Myke

"We're Starfleet officers, weird is part of the job."

Capt. Catherine Janeway

1996\05\23@095150 by reginald neale

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>
> >Some chips blow instantly if you reverse the power supply - not so the 16C84.
> >I accidentally (how else?) plugged one in backwards, and I happened to have
> >an ammeter in series with the power supply - 4 fresh AA size alkaline cells.
> >
> >The ammeter read just over 2 amps - I stood there for about 5 seconds trying
> >to make sense of the reading before realizing what I had done. Pulled it out,
> >put it in the right way, and away it went!
> >
>
> Yah, I did the same thing a couple of nights ago, I use a ZIF socket for
> prototyping and put the 'C84 in backwards.  Something was smoking, the power
> supply's fuse went, but after putting in a fresh fuse, opening a window, I
> tried the PIC again and no problems (including reprogramming it)!
>
> Pretty tough little cookie!
>
Yeah, I'm ashamed to admit that I have done the same with the windowed
16C71 part. Ithought I could see a red glow through the window! But when it
cooled down and was inserted the right way, it still worked.
It's nice to work with a device that's at least partially idiot-proof.


....Reg Neale.............standard disclaimer applies.......
"Ignorance is a renewable resource."    P. J. O'Rourke......

1996\05\23@103401 by Norm Cramer

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>It's nice to work with a device that's at least partially idiot-proof.
>
>
>....Reg Neale.............standard disclaimer applies.......
>"Ignorance is a renewable resource."    P. J. O'Rourke......


Nice to know when doing prototype work!

The problem with making things idiot-proof is that they keep making better
idiots!  I'm sure I will eventually blow one up.


Norm

1996\05\23@114046 by John Payson

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> > Yah, I did the same thing a couple of nights ago, I use a ZIF socket for
> > prototyping and put the 'C84 in backwards.  Something was smoking, the power
> > supply's fuse went, but after putting in a fresh fuse, opening a window, I
> > tried the PIC again and no problems (including reprogramming it)!
> >
> Yeah, I'm ashamed to admit that I have done the same with the windowed
> 16C71 part. Ithought I could see a red glow through the window! But when it
> cooled down and was inserted the right way, it still worked.
> It's nice to work with a device that's at least partially idiot-proof.

Yeah, them PICs are really something.  The only ways I've managed to destroy
'em are either:

[1] mechanical wear on the legs cripples them

[2] too much voltage on a port pin, with current to back it up [e.g. rect-
   ified raw power line--170v DC!]  Note: even this didn't blow up the whole
   chip--just the affected port pins.  Unfortunately, blowing up PB7 leaves
   the chip's code in a somewhat permanent state (the code that was in there
   still ran, but there was no way to change it)

1996\05\23@122201 by Martin J. Maney

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On Thu, 23 May 1996, John Payson wrote:

> Yeah, them PICs are really something.  The only ways I've managed to destroy
> 'em are either:
>
> [1] mechanical wear on the legs cripples them

But isn't the first thing one does with an expensive CERDIP part to place
it into a nice machined socket, like these Mill-Max parts I have the '73s in?

Actually, I'm sure that this will fail for a sufficently fast part, but
how fast is too fast?  The '73 is perfectly happy, but I'm only clocking
it at 4MHz 'cause that's the design target.

1996\05\23@133734 by Norm Cramer

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At 11:21 AM 5/23/96 -0500, you wrote:

>But isn't the first thing one does with an expensive CERDIP part to place
>it into a nice machined socket, like these Mill-Max parts I have the '73s in?
>
>Actually, I'm sure that this will fail for a sufficently fast part, but
>how fast is too fast?  The '73 is perfectly happy, but I'm only clocking
>it at 4MHz 'cause that's the design target.
>

I would imagine that the speed where this is a problem is well past the
fastest PIC.  You really aren't adding that much distance or capacitance to
the circuit doing this.  I have seen this work in a 50MHz logic board that
used this method to get a logic probe onto the pins of an FPGA.

1996\05\23@203245 by John Payson

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>
> On Thu, 23 May 1996, John Payson wrote:
>
> > Yeah, them PICs are really something.  The only ways I've managed to destroy
> > 'em are either:
> >
> > [1] mechanical wear on the legs cripples them
>
> But isn't the first thing one does with an expensive CERDIP part to place
> it into a nice machined socket, like these Mill-Max parts I have the '73s in?

For Cerdips, I probably would; for the PIC 16C84, I didn't think it worth
doing, especially given that I've broken one and fried 3 [with 100+ volts
DC or AC]

1996\05\23@232140 by Martin J. Maney

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On Thu, 23 May 1996, John Payson wrote:

> For Cerdips, I probably would; for the PIC 16C84, I didn't think it worth
> doing, especially given that I've broken one and fried 3 [with 100+ volts
> DC or AC]

I'd forgotten about the EEPROM '84.  Plastic DIP package leads aren't as
fragile as those welded to the edge slivers on the '73, but any part I was
planning to pop in and out of a socket a bunch of times I'd prefer to have
in a carrier.  Unless the sockets were all ZIFs, or it was just physically
impossible.

Even '84s aren't really cheap - not compared to a dollar or two for a
machined socket that may well outlive the chip if it isn't abused.  <shrug>

1996\05\24@104837 by Martin McCormick

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       one person mentioned seeing a red glow from the window of a PIC
which had been plugged in backwards and still survived.  What could have
gotten hot enough to actually glow in a simiconducter chip with the chip still
functional afterward?  I remember seeing a film on the mass production of
IC's and remember that
gold solder is used to connect each pin to the body of the die, so I wonder
what got that hot and didn't melt or vaporize?

       Is it possible that at least some PIC's have reverse-protection diodes
included in the package since this isn't exactly an un-heard-of accident?

       Since the amount of current drawn by a properly-operating PIC is
orders of magnitude smaller than even 1 Amp, a properly designed power supply
could be expected to shut down in some way in a fraction of a second so that
the reverse protection diode would only need to hang in there for that time to
save the PIC.

Martin McCormick 405 744-7572   Stillwater, OK
OSU Center for Computing and Information services Data Communications Group

1996\05\24@112321 by Przemek Klosowski

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          one person mentioned seeing a red glow from the window of a PIC
  which had been plugged in backwards and still survived.  What could have

IT couldn't have been the thermal radiation: red glow would mean several hundred
degrees C, and neither semiconductor nor bondings nor packaging would survive
that.

The red glow results from carrier recombination (LED mechanism) in
forward-polarized substrate p-n junction. Such mechanism is well known
in e.g. transistors; Bob Pease recently gave a puzzler in his column
where he would run high current through one junction of a bipolar
transistor, and observe negative photoelectric voltage on the
remaining connector. There was a discussion of that on sci.electronic.design
usenet newsgroup.

               przeme

1996\05\24@150557 by Eric T. Brewer

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At 8:32 AM 5/23/96, John Payson wrote:
{Quote hidden}

Sounds like a good way to really code protect your devices! Just blow away
PB6 and PB7 on the newer (ISP) devices! ;)

eric

1996\05\24@154419 by fastfwd

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Martin McCormick <PICLISTspamKILLspamMITVMA.MIT.EDU> wrote:

> one person mentioned seeing a red glow from the window of a PIC
> which had been plugged in backwards and still survived.  What
> could have gotten hot enough to actually glow in a simiconducter
> chip with the chip still functional afterward?  I remember seeing a
> film on the mass production of IC's and remember that gold solder
> is used to connect each pin to the body of the die, so I wonder
> what got that hot and didn't melt or vaporize?

Przemek Klosowski <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU> responded:

> IT couldn't have been the thermal radiation: red glow would mean
> several hundred degrees C, and neither semiconductor nor bondings
> nor packaging would survive that.

   Actually, it often IS thermal radiation from a bonding wire.
   They'll glow yellow for a number of seconds before vaporizing.

   -Andy

Andrew Warren - EraseMEfastfwdspam_OUTspamTakeThisOuTix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499

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