Re: Voltage Protection

Walt Jung's "Op Amp Applications Handbook" has a chapter on device
protection -- chapters of the book are available on Analog Devices website,
or you can purchase the book online.

To protect ADC input pins you may want to buffer with an opamp in unity gain
configuration. To the non-inverting input you attach two shunt diodes, a
1n4148 for example, or better yet a Schottky 1n5711 -- the first is
connected "A" to input pin, "C" to Vcc. The second diode's "C" to input
pin, "A" to Vee (or ground). Use a 1K resistor in series with the
non-inverting input to limit current.

Jung points out that glass rectifiers will experience a photo-voltaic
effect -- small potatoes in your application but problematic if you really
have to measure something.


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