> Van: Russell McMahon <apptech@CLEAR.NET.NZ>
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: More on (ab)use of PIC protection diodes & bad design
> Datum: zaterdag 9 oktober 1999 1:38

Hello Russel,

  The story below tell's me that the protection-diodes should be protected
..

Normally I would discard such a story as an hoax.  But you seem to be
serious about it.  Could you try to explain ? (in as simple as terms as
possible please ...)

What's so specific of those internal protection-diodes that they can't be
used like their external counterparts ?

Regards,
  Rudy Wieser



> MANY people over time on this list have supported the use of the PIC's
> internal diodes to clamp signals to an acceptable level.
> DON'T DO IT.
> The PIC is guaranteed "safe" at up to 20ma protection diode current.
> The PIC is NOT guaranteed to work properly with ANY protection diode
> current.
>
> It will often (even "usually") work "OK".
> It is unacceptable design practice.
> It is not guaranteed to work.
> There is no certainty what the results on the processor will be.
> Sometimes a whole design will fail because of it.
> There will often be no indication of what is wrong.