[sdiy] Best way to get a +3.3V rail from +15V?

Richie Burnett rburnett at richieburnett.co.uk
Thu Mar 7 16:54:45 CET 2013

If you want the most compact & efficient solution, then use a switching regulator. (It's technically a buck converter.) There's probably something suitable in National Semiconductor's Simple Switcher range. All you need is the switching IC, a Schottky diode and a couple of resistors and Low-ESR electrolytics.

If it's just for a quick lash-up you could always just go with a linear regulator though, bolt on an appropriately sized heatsink and benefit from some winter heating! ;-)


Sent from my Sony Ericsson Xperia ray

Tom Wiltshire <tom at electricdruid.net> wrote:

>Hi all,
>I'm putting a little dsPIC prototype dev board together for mucking about on. I've done such things before, but I've always had a +5V supply available, so when I've needed a 3.3V rail for the dsPIC, I've stuck a regulator on the 5V supply. Which was fine, but that's not the situation this time.
>If I've only got +/-15V available, what's the best way to derive a 3.3V rail?
>I've used 3.3V regulators on the 15V rail before and found they got hot, which wasn't a surprise seeing how much voltage they've got to lose somewhere. But perhaps I was doing something wrong?
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