> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Forrest W Christian
> Sent: 03 December 2010 04:03
> To: Microcontroller discussion list - Public.
> Subject: [EE] Precision ADC design.
>=20
>=20
> The other thing that's bothering me is the lack of a precison
reference
> with extremely low ppm/C rating.   With the 80*C application range I'm
> talking about, and typical voltage references in the 50ppm/C range, I
> end up with +-0.4% overall temperature drift.   Or 0.24V at full scale
> error - which isn't going to work.
>=20
> Short of building an oven, is there something else I can do to get a
> decent reference voltage for the ADC?  I haven't seen a
> voltage-reference equivalent of a TXCO, and even if I did I suspect
that
> it would be horribly priced.   Plus, I'm trying to keep low power here
> (this product will be used at times in  a solar powered application),
> and burning power to heat up a voltage reference doesn't sound like
> low-power to me.
>=20

Would it be possible to apply some calibration/temperature compensation
to the ADC value?  This could allow you to overcome the initial resistor
accuracy and the tempco of the resistors and reference.

Regards

Mike

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

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