I know this should be OK in theory as it is in the manufacturer's specs, but
in practice I would never design a curcuit for mass production like that, or
do anythink that could take any pin outside the supply voltage range, even
using schottkey diodes to clamp the pins could be dangerous. There is a
parasitic scr in every chip waiting to be fired!

----- Original Message -----
From: "Spehro Pefhany" <speff@INTERLOG.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 25, 2002 5:12 AM
Subject: Re: [PIC] kill a PIC


> At 12:12 PM 2/24/02 +1100, you wrote:
>
> >I can see no problem with this, as long as the series resistor
> >is large enough to limit the maximum current to the manufactures
> >specification.
>
> I don't see any *inherent* problem with it, but trying it with a
> standard 0.25W resistor is practically guaranteeing trouble, and
> I doubt it would pass safety certification in any developed
> country.
>
> Instead use an approved resistor rated for a few thousand volts,
> which might cost 10-20 cents rather than << 1 cent. Philips'
> VR37 series meets the requirements, and can be bent to fit 0.5"
> pitch pads.
>
> The value should be high enough that enough current to cause
> latchup will not flow *even under transient conditions*.
>
> Best regards,
>
>
>
>
>
>
>
> >.......................... Zim
> >
> >--
> >http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body
>
> 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
> 9/11 United we Stand
>
> --
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>
>

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