EMRFD Message Archive 1611
Message Date From Subject 1611 2008-04-27 20:58:28 Mike Czuhajewski OT: Power supply switching frequencies Somewhat off topic, but I'm sure someone here has expertise in this area
The question is related to a little research project I'm doing: What are
"typical" frequencies used in switching power supplies? I read somewhere on
the web that they can go well over 1 MHz, although something seen elsewhere
tended to indicate that they are usually well under that in most cases. I'm
not looking for specific frequencies, just trying to get a general idea of
what range is used. (This is not an SMPS project; my quest for knowledge
involves diode behaviors.)
73 DE WA8MCQ
1612 2008-04-28 06:05:32 John Levreault Re: OT: Power supply switching frequencies It depends on power. For medium- and high-power discrete designs, up to
maybe 2KW, figure 50-100kHz, sometimes a bit more for the lower end of
the scale. This keeps the magnetics manageable without frying the
semiconductors. The higher the switching frequency, the smaller the
magnetics, but the larger the switching losses in the semiconductor
devices, so it's a bit of a balancing act.
For lower powers, up to maybe 10-20W or so, you might want to spend some
time fiddling with Webench at www.national.com to see what their chip
solutions can do. Their earliest switchers, like the LM2575, ran at
52kHz, but some of their newest stuff can go over a MHz. The lower the
voltages involved, the faster you can push them, since low-voltage
MOSFET's have much lower nodal capacitances than high-voltage ones.
Too much information or not enough?
de John NB1I
Mike Czuhajewski wrote:
>Somewhat off topic, but I'm sure someone here has expertise in this area
>The question is related to a little research project I'm doing: What are
>"typical" frequencies used in switching power supplies?