Andy Errington wrote:
>
> Can anyone recommend a good cheap A/D chip for interfacing to a Stamp or
> PIC?

Have you considered a voltage-to-frequency converter? National Semiconductor
makes an LM331 that satisfies:

>
> What I am looking for is:
>
> 10bit resolutionNo problem. In fact 14 bit resolution is easily achievable.

> serial data outA matter of interpretation. The "serial output" is a clock.

> 8 pin DIL packageYes

> 0-2.5v or 0-5v analogue in rangeNo problem, although you will need an external
 analog switch to dynamically obtain
both ranges.

> Single rail supply (5v pref)Yes

> Cost less than 10GBP in one-off quantitiesDigikey lists it at ~8USD in one-of
 quantities, but then the price drops in half in 25 piece
quantities.

> Fast conversion is not important, I am only interested in a value once per
 second.Good, because the V/F converter is not fast.


Another good feature of V/F converters is that they inherently low pass filter
 and can also
be designed to notch out certain frequencies (such as 50 or 60 Hz). In fact,
 I've obtained
over 100dB of normal mode rejection at 60Hz!


Scott