AD and PIC interfacing problem
Chris Fanning email (remove spam text)
> At 11:27 PM 10/18/99 -0400, Sean wrote:
> >How can a non-inverting follower work without at least a negative supply? I
> >interpreted "negative reference" to mean "negative supply" in this case.
> >If we could use an inverting buffer, THEN it wouldn't need a negative
> >supply. However, good luck finding a high enough Rin,
> As far as I know, you never need to have bipolar supplies. You just need a
> Vss and a Vdd and a common point in between, typically at the midpoint.
> The common voltage becomes the signal ground. The full Vcc becomes the
> 'plus' voltage. The power supply ground becomes the 'minus' voltage.
>From what I can tell, you're suggesting to basically connect one end
of the electrode to 2.5V. I'd then be running current through the
electrode and I'm not sure that's a good thing...
I found an interesting part in the Burr Brown INA116 differential
amplifier. Not too cheap but seems ideal for this. Looks really
easy to use too. Just get a 2.5V reference, plug in a resistor for
gain and I'm set. My concern would be ESD with this device though.
Any way to help control ESD across really sensitive inputs?
Unless there's a convincing argument otherwise, I think I'm going to
go with this part instead of DIYing a differential amp with lots of
The LMC660 looks like a good cheap part. I'll probably use that for
Thanks for everyone that replied to help me get this input into a PIC.
In reply to: <firstname.lastname@example.org> from "Robert A. LaBudde" at "Oct 19, 1999 10:32: 7 am"
See also: www.piclist.com/techref/microchip/devices.htm?key=pic
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