pic microcontroller discussion list <> wrote on Thursday, April 24, 2003
3:11 PM:

> The input Cap I am using is EL Cap 470 uF (16 V), the input voltage
> is DC 19 V (unloaded) and loaded is around 15-16 V. My question is
> what will happen theoretically to the EL Cap if the input voltage is
> higher than max rating of the Cap. Currently the circuit still
> functioning without problems.

It will eventually die.  It might die spectacularly (ie the end pops out
and covers everything around it with a thin layer of gunk) or it might die
half-heartedly (capacitance drops to 0 at some point before the expected
end of life, anything from 1 second to 10 years, no sure way of telling).

Either way, it's worth using an over-rated as soon as you can get hold of
one, cleaning up after the first failure mode can take a while, BTDTGTTS...

I usually use 2x rating for electrolytics and tantalums, so you would want
a > 38V part, but 35V should be fine if ultimate reliability isn't a
problem.

Nigel

--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk

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