At 09:26 AM 10/11/2000 -0400, you wrote:
>Would an analog switch IC that is passing signals from another board need to
>have its switch contact pins protected similar to the recommendation for
>microcontroller inputs?  If so, how would one go about doing that without
>inhibiting the signal through the IC switch?
>
>In my case it's not a big deal to obstruct the signal, I'm not passing an
>analog signal that is attenuation sensitive, I'm just shorting two digital
>lines from afar and then releasing them after momentarily asserting them
>with the PIC.  But if I should be ESD conscious again on this section of the
>circuit, I'd like to be prepared...
>


4066s are CMOS and thus subject to ESD. One possibility is adding
transzorbs with a small series R at the input and output pins of
the board. Ideally, these would be located right at the board
edge, and it would be best to have the anodes of the transzorbs
tied to a separate heavy gnd trace on the edge of the board so
ESD currents would not be conducted thru the normal ckt gnd traces.
This would not work with bipolar signals however.


I/O <---R---+----> to 4066
            |
          \---\
           / \
           ---
            |
      ------+--------separate gnd trace

- danM

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