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Low Voltage Clamp for Microcontroller

Firebringer

Nov 7, 2011
2
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Nov 7, 2011
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I'm currently playing with a microcontroller with sensor inputs that detect and report voltages. I'd like to hook these up to several different types of probes (temperature, light, current, etc).

The uC, however, needs to be protected as a voltage in excess of 1.2v _might_ permanently damage it. I've read some articles that say a standard Zener clamp circuit is really designed for 5v or more. (see Voltage clamp circuits for ultra-low-voltage apps)

The referenced article suggests using a MOSFET, but this seems to be for higher currents voltages (up to 1A) -- I don't need anywhere near this kind of current handling. Is there a reasonable middle ground circuit that provides adequate protection at 1.2v with the simplicity of a Zener clamp?? NOTE: This is all DC.

thnx
firebringer
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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25,510
Two forward biased diodes should do the trick.
 

Firebringer

Nov 7, 2011
2
Joined
Nov 7, 2011
Messages
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Hmm. A standard diode wouldn't work here (too much forward voltage), but maybe a schottky??

How stable do these tend to be?? How much tolerance expected in manufacturer's specs??

For purposes of design, I'm treating the 1.2v as an _absolute_ ceiling.

thnx
firebringer
 
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