Neil,

Found 'em
Transformer design
http://www-s.ti.com/sc/psheets/slup062/slup062.pdf
http://www-s.ti.com/sc/psheets/slup073/slup073.pdf
Coupled inductor design
http://www-s.ti.com/sc/psheets/slup105/slup105.pdf
Magnetics design handbook
http://www-s.ti.com/sc/psheets/slup123/slup123.pdf
http://www-s.ti.com/sc/psheets/slup124/slup124.pdf
http://www-s.ti.com/sc/psheets/slup125/slup125.pdf
http://www-s.ti.com/sc/psheets/slup126/slup126.pdf
http://www-s.ti.com/sc/psheets/slup127/slup127.pdf
http://www-s.ti.com/sc/psheets/slup128/slup128.pdf
http://www-s.ti.com/sc/psheets/slup129/slup129.pdf

Best regards,
Dave

David Minkler wrote:
>
> Neil,
>
> TI's knowledge base server is presently down so I can't give you a link
> at the moment however, when they come back up, look at the Unitrode
> Power Supply Design Seminar Archives.  I'd recommend slup062.pdf,
> slup073.pdf (both on transformer design), slup105.pdf (on coupled
> inductor design - which is what you are doing) and slup123.pdf through
> slup129.pdf a good basic magnetics handbook.
>
> Best regards,
>
> Dave
>
> PicDude wrote:
> >
> > So in my experiments with switcher chips, I've found a
> > common point of failure.... the transformer.  And I guess
> > I need to learn more about designing/building a transformer
> > for switching-freq applications.  Here's why I say this...
> >
> > Over the past couple weeks, I've built a number of switcher
> > circuits... 5 buck circuits (using LM2678 and MC33167 chips),
> > 1 boost circuit (LM2588), and 3 flyback circuits (LM2588,
> > and MC33167).  Using off-the-shelf inductors, the buck and
> > boost converters work.  Replacing those inductors with my
> > own home-wound inductors, they still work very well.
> >
> > BUT.... for any of the circuits that require a transformer,
> > they don't work.  I've even followed guidelines for adding
> > additional outputs to a couple of the buck designs by tapping
> > off the inductor to make a transformer, but the primary
> > outputs still work while the tapped-off secondary outputs
> > do not.
> >
> > No, not very scientific w/o an oscope, but it seems obvious
> > enough that it's my transformers.
> >
> > SPECIFIC EXAMPLE ... LM2678 buck ckt (9Vin, 5Vout) works
> > well with my own inductor -- 21 turns of 18AWG on a T130-3
> > toroid.  Followed NS's doc for adding another output f/12V
> > (48 turns of 18awg) but that failed, leaving me with ~3-4V
> > out.  The 5V output still functions fine though.
> >
> > Anyone have good info/links on how to design/wind transformers?
> > I've searched the local bookstores, but no dice.
> >
> > Cheers,
> > -Neil.
> >
> > --
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>
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