At 02:06 PM 22/02/2010, you wrote:
>On 2/22/2010 10:52 AM, Funny NYPD wrote:
> > For  most of the electrolytic capacitor, they cannot be used  when
> > application voltage is higher than the rated voltage. For ceramic
> > Capacitors, they won't be damaged if the application voltage is
> > higher but doesn't go above 1K Volts~a few Kilo-volts.
> >
>
>Where did you get that idea?  Voltage ratings are not "optional"...

Ceramic caps don't generally need to be DE-RATED by much compared to other
types for higher reliability, but you shouldn't exceed the maximum voltage.

You seem to be thinking of voltage coefficient, which can indeed be
awful on types such as Y5V (40% loss at rated voltage), but temperature
effects are even worse if you need to operate over a wide range (they
virtually cease to exist electrically at 90 or 100C), and there are also
pronounced aging effects for most types (even the relatively stable X7R/X5R).

http://www.johansondielectrics.com/technical-notes/product-training/basics-of-ceramic-chip-capacitors.html

Unfortunately, NP0/C0G caps are still prohibitively expensive in larger
capacitances such as 0.22uF.


>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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