Hi,Roman,
you are joking, aren't you?
 The cost of the circuit is not the only thing, I'm obsessed
with. Technical parameters declared in the LM3485
datasheet mean something (input range, adjustable
output range, efficiency, maximum operating frequency...)

   Mike.

Roman Black wrote:
>
> Hi Mike, it's not cheap at all, $0.50 x 1000.
> In the circuit you showed you could probably replace
> the LM3485 with a cheap 8 pin comparator chip, or
> even a transistor and zener. With that many external
> components and FET
> you have many options for a much cheaper circuit.
> (once you are buying 1000 of them!) :o)
> -Roman
>
> Mike Singer wrote:
>
> > > It is unlikely that you could build an IC based switching
> > > regulator for a component cost much cheaper
> >
> >  Not cheaper (LM3485 is $.50 1K+), but
> > nevertheless, interesting. From LM3485 d
> > atasheet:
> > 4.5V to 35V wide input range
> > 1.242V to VIN adjustable output range
> > High Efficiency 93%
> > Maximum operating frequency > 1MHz
> >
> > Look at attached "Typical Application Circuit".
> >
> >  Mike.
> >

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