>>But I'm worried that it's not a simple matter of using
>>a 500mV voltage reference as noise may play a bigger part
>>at this level leading to innacurate/inconsistent readings.
>
>Yeah - just use the standard 10 bit a/d converter in most newer PICs and
>use Vdd as the reference.  You state that you need at least 10 mV
>resolution: 10 bits gives you 5 mV resolution.  12f675, 16f676, 16f877,
etc.

Or if you really wanted to give yourself a bit extra resolution then plan on
being able to reduce the Vref+ to 2.5V. At least build in the pads that
would allow a TO92 reference to be fitted later to do this as someone will
sure as eggs want better resolution :))

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