Much easier to filter the ripple too.
John Devereux
MC34063 with small inductors
Apr 07, 2010
64 Replies
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...
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(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:
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Inverter board:
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(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
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