From: "R. Lewis"
Subject: Re: tiny inverter driver
Date: Wed, 2 Oct 2002 22:04:17 +0100
Organization: Nextra UK
NNTP-Posting-Date: Wed, 2 Oct 2002 21:06:59 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 5.50.4133.2400
"John Larkin" wrote in
> I'm helping a very nice guy I know to develop an electro-optical
> module. He has a really cool optically-active material, but it needs
> high voltage.
> We're putting together a demo that needs to look all nice and
> packaged, 5-volt only input, which means I have to squash, among other
> things, a 0-800 volt power supply into the thing. I'm probably going
> with a classic dual-fet foreward DC/DC converter, and I'm currently
> figuring on a SOT-23 schmitt gate RC oscillator driving a Tiny Logic
> flipflop driving a pair of SOT-23 fets, finally driving the
> center-tapped transformer primary. The transformer will be a 7 mm dia
> ferrite pot core, followed by a C-W multiplier. All this, plus the
> optics, in about the footprint of an eprom. Whew.
> So my question: does anybody know of a gadget that would replace the
> oscillator/flipflop mess? Or know of any other cool but *very small*
> inverter drivers? There are some small flyback driver chips, but a
> flyback is less transformer-efficient.
> Any other suggestions appreciated. Hey, it's not as if I'm doing this
> for money.
You do not say what sort of power (current) you require at 800V but in any
case the size of the magnetics is going to be determined by this power
To keep it small look at the Royer and Hartley inverter topologies much
beloved of the emergency lighting boys (outputting 1kV from 3.6 volts is
common place to them).
The simplest (hartley type) inverter would be the wound component plus 1
resistor, 1 capacitor, & 1 transistor