A 3rd reason to add to what Byron said:

Most 5V regulators are +/- 5%, maybe greater. It's easy to find a
1% or less voltage reference. Your uncalibrated accuracy is much
better in this case, even if you use a 5V external reference
because the voltage spread between a number of units will be much
less.

Matt Pobursky
Maximum Performance Systems

On Thu, 27 Jun 2002 22:22:42 -0400, Brandon Stewart wrote:
>What is the purpose of having this Vref?  Why not use the
internal 5V
>reference all the time?  If it is for accuracy reasons, then if
your
>5v line
>goes wacky... then can you count on the PIC during that time
anyway?
>
>
>
>Thanks,
>Brandon
>

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