Re: 100VDC to 13.5VDC simple switcher

On Sat, 02 Dec 2006 23:57:21 -0500, John Popelish wrote:
Rich Grise wrote:

Pardon my ignorance, but what exactly is the advantage of using a boost
converter to go from 30~100VDC to 13.5VDC?

I thought "boost" meant to _increase_ the voltage above the input voltage.
Or does the choice of topology have something to do with line
regulation/input voltage range/something like that?

The boost configuration is one that stores energy in an
inductor's magnetic field and then dumps it to the output.
If the inductor is also a transformer or autotransformer,
the output may have a higher or lower voltage than the
source. One reason you might use a boost (flyback)
configuration rather than a buck converter to step a voltage
down, is that the step down transformer can also provide
input to output isolation. And the turns ratio of the
transformer/inductor gives you a degree of freedom you don't
have with a simple buck converter.

However, I seldom find that the boost configuration is the
overall best (all warts considered), except for low power
applications. The peak currents are at least 4 times the
average current.

Ah! Got it! :-)

Thanks!
Rich

.

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