I think this one will help you:

http://www.digikey.com/en/articles/techzone/2012/apr/protecting-inputs-in-d=
igital-electronics

Vasile

On Fri, Nov 28, 2014 at 5:34 PM, Jason White <
whitewaterssoftwareinfo@gmail.com> wrote:

> Thanks Vasile, I read a few app notes and made some changes.
>
> Heres what I have so far (see attached). I added a zener along with
> several capacitors to help shunt the ESD discharge. I also attempted
> to model the pulse and parasitics in the attached LTSPICE file. I'm
> not sure if its terribly accurate, it is showing to transients of +-1v
> at the base of the transistor using the machine [ESD] model.
>
>
>
>
>
> --
> Jason White
>
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