Clever Switch Mode Circuits..

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While looking for a shortcut in generating a high side NMOS gate supply, I came across this little gem.
Not applicable to my task but still appreciable none the less.

From here: http://www.datasheetdir.com/Ucc3813-Dual-Output-Boost-Converter+Application-Notes

Anyone have interesting switch mode circuits to share?
Adding windings to inductor, clever tricks, etc..?

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Apart from the charge pump for the negative rail, what is unique about the above circuit? Depending on the current, something like a ti simpleswitcher would do the same with less components.

You can put extra windings on L1 and it becomes a flyback inverter. You'd need to add snubbing on the primary side. Then it becomes an isolated converter.

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You can also make a switching converter (buck) with any of the 78xx linear regulators.

If you want to go crazy, google "roman black" and find his converter page. Out of curiosity, I breadboarded one up out of junk box components and nothing near the values his schematic indicates, and the silly thing works.

If you need a 3v supply in a 5v system and have a spare PWM output, just set your PWM to 3/5 duty cycle at a pretty high frequency, and put it through an inductor with a cap on the output. I saw this, I think, on Lady Ada's site.

The largest known prime number: 282589933-1

In my humble opinion, I'm always right. 

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@Kartman, just the charge pump, anywhere an oscillator...

@Torby, likewise out of curiosity & much like a jewel thief. That lady's clever pretty...

This circuit seems to work well with an LM2577 boost, have some MC33063 on order.
I've added a shutdown to the comparator input to reduce noise while I sample & hold...

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