> Thank you for all replies. I would like to address one in particular:
>
> Just one question, why 50V? Just because it's very difficult to find 100n=
F ceramic capacitors
>  of lower voltage, or 50V specification is truly needed (but why? it's a =
3.3V circuit after all).

One of the problems with ceramic capacitors is the way they vary their capa=
citance with applied voltage. There is a good graph in the Microchip datash=
eets that discuss bypassing the Vcore voltage generated by internal voltage=
 regulators that illustrates this. Essentially it becomes a case of using t=
he highest rated voltage you can obtain in the case size you can fit gives =
the minimum change in capacitance with voltage.

This change in capacitance with voltage causes what audiophiles describe as=
 'capacitor distortion' in amplifiers.

50V used to be common, but as ceramics have improved and requirements for h=
igher capacitance in smaller packages has forced the situation where lower =
voltages have become available.



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