Ok, Roman, Time to put your cards on the table? How do you wind the coil and
what exactly is the circuit?

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-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Roman Black
Sent: Tuesday, August 21, 2001 05:36
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: Design Challenge - low power step down switching
regulator


I'd say it can be done with one transistor and
a very small coil with two windings...
:o)
-Roman


Russell McMahon wrote:
>
> > Requirement
> >
> > Step down voltage regulator suitable for powering small low voltage
> circuits
> > from a higher voltage supply with a reasonable power dissipation.
> >
> > Overall figure of merit = finished cost while meeting design
> specification.
> > Costing rules provided below.
> .................
>
> OK - here's a solution that has been suggested by a friend from the
NatSemi
> LM336 regulator diode data sheet
>
> Without going back to my original cost list I estimate that this is about
> 130 to 150 units cost. (Under $US1 probably with substitutions below). Not
> too bad.
> I've pretended that the LM336 here can be substituted with a low cost
zener
> diode - if not the price is significantly higher.
> I've assumed that all transistors can be low cost general purpose ones
BC337
> / BC327 as the power level specified in my challenge is low.
> Also, the output catch diode could be a 1N4148 ! - not what you would
> normally see in this role but again, the power level is low.
>
> Any improvements on this?
>
>         Russell McMahon
>
>     ---------------------------------------------------------------
>
>                               Name: Lm336buck.gif
>                Part 1.2       Type: GIF Image (image/gif)
>                           Encoding: base64

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