Hi Bill
When it was oscillating what did the voltage look like?
I'm not follow your trouble too closely but I know some regulators will
oscillate if the cap[s] on the output have too little ESR. (I can't see how
it would make you device hot but maybe if it was not regulating the voltage
could be going too high....)
It is something to check
When tantalum was difficult to get a few years back (due to a civil war in
Africa I think) I would use a low ESR ceramic cap with a 1 ohm in series.

 
 
 
 
Phillip
Things should be as simple as possible but no simpler
 
 
 
Phillip Coiner
CTO, GPS Source, Inc.
 
 
Your source for quality GNSS Networking Solutions and Design Services, Now!

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Bill Kuncicky
Sent: Sunday, April 09, 2006 12:00 PM
To: piclist@mit.edu
Subject: Re: [PIC] What are the symptoms of oscillation?]

Jan-Erik Soderholm wrote:


>
> > What is your oscillator config ?
> Any 100 nF cap near the PIC ?
> Any I/O pins configurated as inputs but left unconnected ?
> How is MCLR connected ?
> Anything else you haven't told us ?


.
1.  The oscillator config is a 10 MHz resonator, between OSC1 and OSC2.
Center pin grounded, and of course the resonator has built-in 22 pf
capacitors to ground.

2.  There were not any 100 nf caps from Vdd to Vss.  I have now put them in,
as suggested by Olin Lathrop.

3.  All unused I/O pins are configured as output.

4.  MCLR is tied through a 10K resistor to +5 volts.

5.  I have told you everything that I think is significant, but of course
Murphey's Law says that I have forgotten to tell you something crucial.  :-)

I'm going to let it run awhile with the 100 nf capacitors put in and see if
it fails again.

(Since no one told me whether or not this sounded like oscillation, I guess
it must have).

Bill
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