> I am in a position where I have to input a 0-1 V signal to the A/D of the
> 17C756. To get a reading over the full 10 bit range I would like to set the
> A/D reference voltage at 0 - 1 V.  The data sheet mentions that accuracy may
> be affected when using a reference voltage other than the supply voltages,
> but gives no details (that I could find, also none in the various app
> notes).
> Has anyone here used small(ish) reference voltages - experiences (not
> necessarily on the 17C756 - any pic with an A/D)?  Any comments much
> appreciated!

Hi Roland,

I can't find it(typical of Microchip data sheets, DC data is usually hard
to find) but I seen to recall that Vref must be within 0.5 volt of supply.

Also I recall that accuracy is spec'ed based on 1 or 2 LSB relative to
Vsupply not Vref, so if it were possible to have 1 volt vref you would
have accuracy of +- 5 or 10 LSB.

Cheers,

Bob

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu