At 07:06 21/05/97 +0200, Tjaart van der Walt wrote:
>There is (of course) a catch. In time critical software you'd have a
>hard
>time to fit it into your timing constraints. If you go the whole hog and
>imlement a 16 bit AD with calibration, you'll need some 16 bit maths
>too.

How complex is your analog circuit to get 16 bit precision (not resolution)
out of it? I thought you'd need at least an opamp (for the const charging
current), a comparator (might be the built-in of some of the PICs), and a
good temp compensated reference. And probably a way to do calibration runs
once in a while, i.e. some analog switches.

Easier to get this precision seems to be comparing a PWM output to the
input, but then this is still slower. For slowly changing input signals it
might be useable though; you can track the input, speeding the process
quite a bit up.