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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>
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