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Reply-To: "fred bartoli"
From: "fred bartoli"
Subject: Re: buck switcher problem
Date: Thu, 12 Dec 2002 11:12:00 +0100
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Organization: Guest of ProXad - France
NNTP-Posting-Date: 12 Dec 2002 11:12:36 MET
Frithiof Andreas Jensen a écrit
dans le message : firstname.lastname@example.org...
> "Jeff" wrote in message
> > The surprising thing is
> > that the power supply caps are getting hot.
> That's, in a sense Normal, problem is when they get too hot...
> > They suggest doubling or tripling the caps or using tantalums
> > that are rated for the higher frequency.
> Bad Advice: You would be better off splitting the present one or two big
> cans you presumably use into a larger number of smaller devices. This
> lower the combined ESR and the thermal resistance.
> Look at what the data sheets say - there are curves of permissible ripple
> current vs. frequency - then calculate how many you need to be within
> Also you should confirm that the capacitors you use now are really
> for high frequency/low ESR and not some thrashy 50 Hz consumer component.
> Panasonic make *both* types f.ex.
> Tatalums have additional problems, apart form the price: The ESR can get
> low that they will readily resonate with the PCB leads. This usually
> in a decent "Ka-Boom" when the capacitor subsequently overheats.
> > Any other advice? Is it ok to use aluminum electrolytic at this
> Should be, IF the capacitors are designed for switchers and lots of
> devices are used to make up the capacitance. Look at a Pentium/Athlon
> high-end motherboard for inspiration ;-)
Not the ATI ones though :-)
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