On Fri, 11 Feb 2011 11:44 -0500, "V G"  wrote:
> Hi all,
>=20
> I'm trying to read the output from an amplifier that can potentially
> swing
> from -3V to +3V with an ADC (on a PIC32). Should I use an opamp (LTC to
> "shift" the signal into the positive voltage range? Or can I just use two
> 10K resistors to scale the -3V to 3V output into the 0V - 3V range?
>=20
> I'm leaning towards the resistor divider. Seems simple and effective, but
> I
> wouldn't know any complicated implications it could have. Also, what
> values
> of resistors should I use?

Resistors are fine, since your source has low impedance (probably, I am
assuming since you said "amplifier").

What is the maximum recommended impedance for the PIC32 A/D? Choose your
resistors to be four times that, or less.

Remember that the accuracy will now also be dependent upon the +3 source
on the end of your resistor divider.

Cheers,
Bob

--=20
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