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Old 1st Dec 2017, 10:05 pm   #19
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 5,061
Default Re: Electrolytic capacitor fails after 1 hour in service!

Originally Posted by MrBungle View Post
Out of interest see there any negative transients or positive spikes? Each of those can knacker even the best of electrolytic capacitors in no time at all.
If there were any negative transients, then bearing in mind the capacitor was right on the driver chip, I'd expect the chip itself to have either died, or clamped the negative transient to a volt or so.

Nuvistor and Argus have a point, is it a clone or counterfeit? Or maybe it's just a single bum capacitor?

I've used beefy gate driver chips to drive chunky power MOSFETS, I can't see anything wrong in what you have done. A 1,000μF 63V capacitor should be well up to the job, both in terms of having a low ESR to give a stiff supply to the chip, and also being able to cope with the ripple.

A quick calculation says that if you are taking 2A gulps of current, lasting 15nsec, at a repetition rate of 300kHz (so 3.3μsec apart), you have an RMS value of 135mA. And this shouldn't fry a capacitor of this sort of size.
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