thanks for your help!

in the mean time, i found an application note from national semi, using =
their lm2587.
I think for the only 2amps I need at max, this gives me the smarter =
solution, as the power device is integrated in the controller, i.e. no =
external mosfet is required.
I found some old core, I recycled. it now has about 24uh. so I think =
this should work for a first test.
thanks anyway!
tino

>-----Original Message-----
>From: Bob Blick [mailto:bobblick@COVAD.NET]
>Sent: Thursday, January 08, 2004 5:42 AM
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [EE]: stable 12v supply from 8..16v source
>
>On 6 Jan 2004 at 7:58, B=FChler, Martin wrote:
>
>> hi bob
>> this one looks great, and i think i should be able to get these semis =
in
>europe.
>> what I'm a bit unsure is the inductor. I'm not sure if I will get
>something similar.
>> does this also work with a toroid, or does it have to be a closed =
one?
>> ...and what is the gap for?
>> ...if I find a closed core, does size matter?
>> does this inductor get warm, or can I use wires with plastic =
isolation?
>> what kind of wire did you use?
>
>Don't use a toroid, you need an inductor with a gap, because the =
circuit
>operates in
>continuous mode. It has continuous DC in the inductor, and the gap =
softens
>the
>saturation. The inductor does not get warm unless you run it at maximum
>current, so you
>can use any kind of wire. Here's a link to a fellow's website in =
Denmark
>who built one
>and left out the parts he didn't need. His choice of parts was a little
>funky. One
>modification I made that isn't documented is to feed the chip from the
>output voltage,
>because it has an ~8 volt undervoltage shutoff. By bootstrapping from =
the
>output it will
>run(at reduced output current) down to 6 volts. His stripped-down =
version
>shows that
>modification.
>
>http://dion.swamp.dk/carpower.html
>
>Cheerful regards,
>
>Bob
>
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