> > This is what I'll be trying first... My primary concern is how to go > > about buffering/protecting the inputs; touch + static = fried CMOS! > > Modern CMOS designs generally include clamping diodes at all I/O pads to protect > against ESD. I've never zapped a PIC pin, for example. While most modern CMOS has protection circuits, they are usually only designed to handle moderate jolts. If your using an input that may get jolted often it is sugested you still setup static discharge protection circuits on the inputs. I don't remember the circuits off the top of my head but a common one is to use clamping diodes to ground and Vcc then a resistor inline. The resistor needs to be sized for the expected input signal charateristics. Also along withe the chlamping diodes you need to have a MOV type circuit between Vcc and ground. Between these circuits it should keep all the chips withing their maximum pin to ground or Vcc differentials and keep the Vcc to ground differential within limits. -- | Bryan Andersen || http://softail.visi.com | | Buzzwords are like annoying little flies that deserve to be swatted. | | -Bryan Andersen | -- Subcription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" to
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