From: "Stefan Toftevall"
Subject: Re: High-side switch
X-Newsreader: Microsoft Outlook Express 6.00.2720.3000
Date: Tue, 31 Dec 2002 17:52:33 +0100
NNTP-Posting-Date: Tue, 31 Dec 2002 17:52:33 CET
Organization: A customer of B2 Bredbandsbolaget (www.bredband.com)
Pulse transformers is totally out of the question, since this supply is
going to be very compact and supply
not more than 15W or so, to a stand-by circuit that will in turn control
VERY high power levels.
But that's another story.
High-side switch is what it'll be, in some way.
"Spehro Pefhany" skrev i meddelandet
> On Tue, 31 Dec 2002 14:40:34 +0100, the renowned "Stefan Toftevall"
> >Hi all,
> >I need a high-side switch working as a basic non-isolated step down
> >It will operate directly from mains-voltage of 325V maximum, it will
> >regulate output voltage to 50V by
> >a PWM circuit. Output-current won't be very high, probably max 250mA. I
> >couldn't find any P-channel MOSFET suitable for this high voltage
> There are few, though I think there are 500V rated P-channel MOSFETs.
> Why would you use a high side switch, anyway?
> >Operating frequenzy isn't critical, somewhere between 50k - 100kHz.
> Fairly high. If you could go very low, IGBTs are another possibility.
> >Those charge-pump high-side drivers is interesting, making it possible to
> >use a standard N-channel FET.
> Yes, IR has a bunch of them. Or solutions involving transformers.
> Best regards,
> Spehro Pefhany
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