On Wed, 24 Mar 2010 16:22:59 -0700, Joerg
>
> wrote:
> >Tried the major mfgs and the typical datasheet looks like this:
>
> >
formatting link
>
> >Quote "Capacitance for X7S varies under the influence of electrical
> >operating conditions such as voltage and frequency."
>
> >Then under diagrams ... nada, zip, zilch. Great.
>
> >One paper listed X7S with the same voltage coefficient as X7R but that
> >doesn't sound right. Anyone have a link to some hard data, with a graph
> >in there and preferably no marketing hype?
>
> I seem to recall reading that C0G and NP0 dielectrics have
> the lowest cap-vs-temp dependance and that pretty much
> everyone "understands" that X7R dielectrics have large
> coefficients and are pretty much unsuitable where it matters.
> They pack a lot of capacitance into a small space and that
> makes them great for decoupling jobs and not so much else.
>
> But I don't know remember reading anything about X7S,
> specifically. =A0If they are the same as X7R, they are crap if
> what else I read was right.
>
> Jon
Hi Jon, (though I've never tried this) it turns out that the 'terrible' capacitance change with voltage of X7 and Z5 ceramic caps makes them good as voltage dependent impedances. You could use them in filters and oscillators and such. I've never heard of X7S either.
George H.