Well, I was sort of hoping that part of the "simplification" would be gloss=
ing over that buffer.

I'll have a look at it.  Parking the ADC on the ground input would probably=
 be a good technique to make whatever effect this has on the reading more c=
onsistent.

Thanks.

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of=
 alan.b.pearce@stfc.ac.uk
Sent: Thursday, May 5, 2016 2:44 AM
To: piclist@mit.edu
Subject: RE: [PIC] Glitches on analog input

> > A possible cause is that you are seeing the charge from the ADC's=20
> > internal sampling capacitor. Another possible cause is leakage=20
> > caused by an analog input clamping a voltage above the supply rail.
>=20
> I would hope that wasn't the case.  Shouldn't there be at least a=20
> buffer amplifier between the capacitor and the switch?

Nope, not when you look at the simplified schematics they put in the data s=
heet and family manuals. That is one reason why there is a significant rest=
riction on signal source impedance to maintain the ADC accuracy.

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang=
e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis=
t

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.