Archimedes' Lever wrote:
On Sat, 10 Oct 2009 17:52:52 -0700, James Sweet
wrote:


I want a citation that switchers are commonly running at and above
1MHz.

NONE of ours did.
I've never seen a switching power supply that ran at 1Mhz.

TDD

Just because you've never seen it doesn't mean it doesn't exist or is
not in common use. Here's your citation, note that the article is dated
2002.

http://www.maxim-ic.com/view_press_r...release_id/586


"SMALLEST, 3V INPUT, 1MHz, 92% EFFICIENT DC-DC STEP-DOWN DELIVERS 10A"


So these are not off-line SMPS, but so what? They're still switchmode
power supplies by definition. TI and several others have similar parts.
It is very likely you have one right in front of you supplying the core
voltage to the CPU in your computer.


The chip we used was also capable of switching faster. Again, that
does NOT mean that a designer is going to operate at the max frequency
capability of a chip he is using... EVER!

Get a ****ing clue!

I'm assuming that running your design at a lower frequency would require
less RFI shielding. I've seen some designs that put out so much noise
that it interfered with everything else.

TDD