> >  What sort of caps are you using?
> >Presumably Mylar or similar rather than eg ceramic.
>
> Ceramic at the moment.

Try a Mylar or similar.
MAY not help but don't be amazed if it does.
I am running a Sigma Delta converter with the integrating cap at abourt 1uF.
This is effectively a charge balancing converter - the cap is held more or
less at a constant voltage by a comparator and the processor feedback loop.
It varies slightly from the reference value due to the time quantisizing of
the decision which is an inherent part of the SD process. Anyway - the point
is that the voltage ripples SLIGHTLY about the reference point. A ceramic
capacitor is USELESS here - accuracy is much much worse than when a quality
"plastic" cap is used.
Try it in your case. Easy, quick, cheap and just maybe ....



Russell McMahon

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