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References: <firstname.lastname@example.org> <3D92D0BC.90C30D0D@autometer.de>
Subject: Re: Low power SMPS with good Power factor
Date: Thu, 26 Sep 2002 12:14:03 +0200
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Organization: -= Skynet Usenet Service =-
I think that removing the bulk capacitor in a flyback circuit is a good
solution for the Power Factor because it's mainly the cause of the problem.
The 100Hz ripple is not a problem, but I dont see how to manage the
regulation of the Power supply. All those PWM-chips are not made to
'restart' 100 times a second. What about the transformer? Isn't it getting
I 'll have to cope with a large Duty-Cycle variation.....
Graham Holloway schreef in berichtnieuws
> If you *must* have PFC and are prepared to accept 100Hz ripple on the
> you can operate a flyback with no or a very small input capacitor. It is
> as straightforward as it would seem and there are significant compromises
> be made.
> Graham Holloway
> WPS Electronics
> "Tilmann Reh" wrote in message
> geert schrieb:
> > Which topology should I use when I want to develop a low power OFF line
> > SMPS (230Vac to 16Vdc, 25W with galvanic isolation), with low hamonic
> > distortion. (EN61000-3-2 C)
> > For cost reason, I would not like to build a two-stage power supply like
> > PFC + Flyback.
> > Can I use a sor of PFC - circuit (an extra winding on the choke) to
> > out the power?
> > Is there a passive sollution (no 50Hz chokes, the are too big)?
> There are some pretty chips out there for small power flyback
> applications. And for 25W you don't need PFC.
> Look what Philips or TI can offer...
> Dipl.-Ing. Tilmann Reh
> Autometer GmbH Siegen - Elektronik nach Maß.
> In a world without walls and fences, who needs Windows and Gates ?
> (Sun Microsystems)
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