At 03:25 PM 17/11/2011, you wrote:
>At 08:53 AM 11/17/2011, Sean Breheny wrote:
> >Thank-you to Joe and all who answered. Since I need better than 1%
> >accuracy, I think I best use a solid external reference :)
>
>If you can tolerate a 5V rail, National Semiconductor's LP2950A is a
>5.00 Vdc low-dropout regulator with 0.25% initial tolerance at

That's +/- 0.25V =3D +/-0.5%, right?

>25C.  I suspect that others now make similar regulators in lower
>voltages but I don't have manufacturers or part numbers handy.
>
>Many of my designs use the LP2950A regulator when I need a/d accuracy
>of 1% or better.
>
>dwayne

Yup. Another option is to use a low-cost shunt reference such as the
LM4040, which will give you 2.048, 2.5, 3, 4.096V etc. at 0.1%,
0.2% or 0.5% tolerance. At 0.5% or looser, if current consumption
isn't a worry you can even use a +/-0.5% TL431 variant, which are dirt
cheap (pennies) in volume, because they are used in PC power supplies
and other high volume products. The cheap versions do need about 1mA
to regulate well.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the rewar=
d"
speff@interlog.com             Info for manufacturers: http://www.trexon.co=
m
Embedded software/hardware/analog  Info for designers:  http://www.speff.co=
m



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