how to protect a 3.3v analog pin from being overvoltaged
Topic: how to protect a 3.3v analog pin from being overvoltaged
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Re: how to protect a 3.3v analog pin from being overvoltaged
May 24, 2020, 12:06 am
Are we all assuming that max pin voltage is 3.3volt?
Max (positive) pin voltage happens to be VCC+0.3volt (and GND -0.3volt).
If the Arduino is off, booting up, shutting down, VCC=0volt.
A zener won't protect in those situations.
The requirement also was "without affecting the signal".
A zener will affect that signal, well below it's zener voltage.
Forget about zeners.
Just use an external Schottky clamping diode from pin to VCC if you think the internal ones can't cope.
Another one between pin and ground could protect against negative (below ground) signals.
Curious which sensor we're talking about.