>>
Roman, this circuit is like one of those "Roach Motel" thingies:
energy can check into that inductor, but it can't check out.  Under no
circumstances does ANY of the energy stored in the inductor EVER find
its way to the output circuit.  Nary so much as a picojoule.

Going back over my previous post, I don't see how I could clarify my
explanation any; it seems pretty straightforward.
<<

Roman, I agree with Dave's analisys too.  Here's another way to look at it:

One characteristic that differs between linear and switching regulators is
where the output current comes from.  In a linear regulator, all the output
current comes from the input supply.  In fact, except for the small current
used to power the regulator itself, the output current equals the input
current.

A switching regulator achieves higher efficiency because part of the output
current comes from elsewhere other than the input supply.  This extra
current usually comes thru the inductor via the flyback diode while the
switching element is off.  A theoretical perfect regulator has the input
current inversely proportional to its input voltage.  In your design, ALL of
the output current ultimately comes from the input supply.  Regardless of
what else goes on or why, it simply can't beat a linear regulator for that
reason alone.  All the rest of the circuit just shuffles around where the
energy gets dissipated in dropping the same current from the input to the
output voltage.  In a normal linear regulator, the energy gets dissipated in
the pass element.  In your circuit it mostly gets dissipated in the flyback
diode accross the inductor and in the resistance of the inductor itself.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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