>I used a 7805 for the 5 volt supply and analog reference in a design
>once. It performed well over temp and time as long as the load
>current was relatively constant. There are part to part voltage
>variations which need to be calibrated initially. Sorry I don't have
>any rock solid igures to quote, I just reccollect that it was "good
>enough" for the job (think I was aiming for an overall system
>accuracy of better than 1%).

I find using an LM317 with 270 ohm and 820 ohm resistors to set the voltage
gives a pretty accurate 5V. I have only done it with the surface mount
versions, but it seems to give a good stable reference.

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