On Thu, Jun 26, 2008 at 7:43 PM, Olin Lathrop <olin_piclist@embedinc.com> wrote:
> Not necessarily.  There is no theoretical basis for your statement, and this
> is highly dependent on the circuit.  There are various factors that get both
> better and worse as voltage goes up.
>
> For example, one product I designed works from a wall wart that can provide
> as low as 20VDC, or POE which is nominally 48VDC.  The circuit itself was
> designed to work up to 60V for some margin.  The first stage power supply
> takes this input and bucks it down to about 5.5V.  I have measured the power
> supply, and efficiency is pretty constant accross the 20V - 60V range.
>

Lower the output voltage to say 3V and you will know the effect of
low duty ratio. Or increase the input voltage to say 100V.

Xiaofan
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