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Author Topic: Can arduino adc take negative voltage or not?  (Read 475 times)
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The datasheet mention 0 to 5V. So does that mean the ADC cannot take negative voltage. And that the max amplitude of the analog wave should be 5V and min amplitude should be 0V?

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That's about the size of it. You can go just a little under/over but only about .5v IIRC.

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« Last Edit: January 31, 2012, 04:51:03 pm by Graynomad » Logged

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No it can't.  The chip is a standard CMOS process, if you go more than about 0.5 beyond the supplies you can cause latch-up(*), burn out the protection diodes, generally bad things happen.

If you want to protect the inputs one method is to add schottky diodes to the supply rails to prevent the line going more than about 0.4V out of range (effectively you bypass the on-chip protection diodes completely).

(*) latch up is a CMOS-only failure mode where the chip sudden starts conducting large currents and overheats.  Too much current through the internal protection diodes can trigger this I think.  Only cure is remove supply.

http://en.wikipedia.org/wiki/Latchup
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