Hi All,

I was hoping for some opinions on protecting inputs. I have a data acquisition system design that I'm working on that has 8 digital input lines going to a 3.3vdc Cygnal C8051F226. These are intended as general purpose TTL level input lines. The 8051 is 5 volt compliant. One thought I had was to clamp the inputs to 5 volt and to ground. The other was optical isolation (which is more expensive, and can be harder to get at times). I would thank anyone for their thoughts on the acceptability of these ideas or on other ideas. Thanks in advance.

Josh