PIC16F716 physically exploding

Hi there,

Does anyone have experiencing seeing a PIC16F716 physically blow its
lid (in other words, explode)?  I have a design that uses three SO pkg
of the F716 and one of them is intermittently exploding.  It's always
the same one, and never either of the other two.

I have never seen this before and I don't know what would be causing
it.

Any help appreciated.  Thanks.

Fred

Fred wrote:
> Hi there,
> 
> Does anyone have experiencing seeing a PIC16F716 physically blow its
> lid (in other words, explode)?  I have a design that uses three SO pkg
> of the F716 and one of them is intermittently exploding.  It's always
> the same one, and never either of the other two.
> 
> I have never seen this before and I don't know what would be causing
> it.
> 
> Any help appreciated.  Thanks.

How does something "intermittently explode" ?!?

What is connected to it ?

-jg

On May 3, 6:20 pm, Fred <f...@cs.uml.edu> wrote:
> Does anyone have experiencing seeing a PIC16F716 physically blow its
> lid (in other words, explode)?  I have a design that uses three SO pkg
> of the F716 and one of them is intermittently exploding.  It's always
> the same one, and never either of the other two.
> I have never seen this before and I don't know what would be causing
> it.

A schematic might give us a clue? Or is it too confidential?

On 3 May 2007 17:20:32 -0700, the renowned Fred <fredm@cs.uml.edu>
wrote:

>Hi there,
>
>Does anyone have experiencing seeing a PIC16F716 physically blow its
>lid (in other words, explode)?  I have a design that uses three SO pkg
>of the F716 and one of them is intermittently exploding.  It's always
>the same one, and never either of the other two.
>
>I have never seen this before and I don't know what would be causing
>it.
>
>Any help appreciated.  Thanks.
>
>Fred

If you have a power supply capable of very high current, it could
easily be latchup, but you'd have to be severely abusing the part to
get it to latch up.  



Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Fred wrote:
> Hi there,
> 
> Does anyone have experiencing seeing a PIC16F716 physically blow its
> lid (in other words, explode)?  I have a design that uses three SO pkg
> of the F716 and one of them is intermittently exploding.  It's always
> the same one, and never either of the other two.
> 
> I have never seen this before and I don't know what would be causing
> it.
> 
> Any help appreciated.  Thanks.
> 
> Fred
> 

All PICs have schottky diodes on all I/O pins. Wire -12 volts strong
enough to drive several amps onto an I/O pin and it may blow like you
are describing.

I/O drivers are current limited. You should not destroy PIC by driving
an output against output or voltage source between 0-Vdd.

Your description is not enough, this is just a hint.

--
Roman Ziak
www.dipmicro.com

My power supply is 4xAAs.  No pin is seeing more than 6v.  There is a
diode in series with the batts, but other than that, no current
limiting.

What kind of thing causes latchup?

Have any of you personally seen one of these chips blow?  The tops
literally come off, leaving a 1/4" diameter pock-mark.

Fred

On May 3, 9:56 pm, Roman <m...@dipmicro.com> wrote:
> Fred wrote:
> > Hi there,
>
> > Does anyone have experiencing seeing a PIC16F716 physically blow its
> > lid (in other words, explode)?  I have a design that uses three SO pkg
> > of the F716 and one of them is intermittently exploding.  It's always
> > the same one, and never either of the other two.
>
> > I have never seen this before and I don't know what would be causing
> > it.
>
> > Any help appreciated.  Thanks.
>
> > Fred
>
> All PICs have schottky diodes on all I/O pins. Wire -12 volts strong
> enough to drive several amps onto an I/O pin and it may blow like you
> are describing.
>
> I/O drivers are current limited. You should not destroy PIC by driving
> an output against output or voltage source between 0-Vdd.
>
> Your description is not enough, this is just a hint.
>
> --
> Roman Ziakwww.dipmicro.com

On 2007-05-04, Fred <fredm@cs.uml.edu> wrote:

> My power supply is 4xAAs.  No pin is seeing more than 6v.  There is a
> diode in series with the batts, but other than that, no current
> limiting.
>
> What kind of thing causes latchup?

In the bad old days it was by turning on a parasitic SCR when
you apply a voltage above Vdd to an I/O pin.  Most parts have
protection diodes to prevent that from happening.

> Have any of you personally seen one of these chips blow?  The tops
> literally come off, leaving a 1/4" diameter pock-mark.

I've not seen that particular one blow up, but I've seen others
do it.  I remember one 14-pin DIP op-amp that had supply and
ground pins centered on each side.  If you put the chip in
upside down it would quite reliably blow a chunk out of the
package leaving a nice crater.  If you took a drinking straw
and held one end against the part when you flipped the power
switch you could shoot a chunk of epoxy a fair distance with
some accuracy.

-- 
Grant Edwards                   grante             Yow!  Pardon me, but do you
                                  at               know what it means to be
                               visi.com            TRULY ONE with your BOOTH!

Fred wrote:

> My power supply is 4xAAs.  No pin is seeing more than 6v.  There is a
> diode in series with the batts, but other than that, no current
> limiting.

Add some current limiting, or better, a LDO regulator.

> 
> What kind of thing causes latchup?

Current injection into the parasitic SCR all CMOS devices have.
can be -ve or +ve spikes, of short duration - just need to
be long enough, and of enough magnitude, to  fire the SCR.
Once fired, it attempts to crowbar the Supply
- in this case, loosing :)

What is connected to this chip ?

-jg

The only time I have seen top off and crater is when the part
joined the 110 club. 220 or 240 in other countries

I have seen some very hot parts from latch up but never one to
explode.

w..

Fred wrote:

> My power supply is 4xAAs.  No pin is seeing more than 6v.  There is a
> diode in series with the batts, but other than that, no current
> limiting.
>
> What kind of thing causes latchup?
>
> Have any of you personally seen one of these chips blow?  The tops
> literally come off, leaving a 1/4" diameter pock-mark.
>

"Fred" <fredm@cs.uml.edu> wrote in message 
news:1178238032.071062.282870@c35g2000hsg.googlegroups.com...
> Hi there,
>
> Does anyone have experiencing seeing a PIC16F716 physically blow its
> lid (in other words, explode)?  I have a design that uses three SO pkg
> of the F716 and one of them is intermittently exploding.  It's always
> the same one, and never either of the other two.
>
> I have never seen this before and I don't know what would be causing
> it.
>
> Any help appreciated.  Thanks.
>
> Fred
>

Where is this device used?  We have controllers in remote areas that are 
subject to lightning strikes.  The spark gaps and input protection usually 
handle it, but sometimes we get controllers back with missing chips and lots 
of epoxy powder.

Mark Walsh
Rogue Engineering Inc.