MC34063 with small inductors

Yup. All 0805 ceramic caps.

John

True. Smaller, too. Especially nifty when you can use ceramic caps. But, ripple's pretty easy even at 50-100KHz.

Methinks there's probably a voltage dependence--optimal 5-to-3.3v and

48-to-5v converters won't look the same. (E.g., (1/2) f*c*v^2 switching loss isn't a big deal for low-voltage switchers, so they can really scream.) I'm too lazy to calculate numbers for a real supply just now.

Hmmm. I try to keep total switching time under roughly 10% of the PWM period. At 3MHz that's 17nS per transition. Pretty do-able at 5v, actually. But that's supply's so generic you might as well just buy it.

-- Cheers, James Arthur

I've done 1MHz discrete. Didn't come out all that efficient though, needs work...

(note the output filter cap specifically *isn't* tantalum... ESR compensates the loop)

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Seems to me, D from BC was working on some 1MHz offline switcher. Something about big loads of EMC from the transistor-to-heatsink capacitance.

I'm going to try an induction heater at 1MHz sooner or later. C0G tank cap:

Inverter board: (the whole high side is top and bottom ground plane floating at the 1MHz output)

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms