RE: [EE]: Design Challenge - low power step down switching regulatorMichael
asked me to forward this URL to the list as his mesages are being bounced at
present.

________________________________________________________________

Sorry to email you directly, but I can no longer post to the mailing list,
every mail is bounced.
There has been an awful lot of interest in your Switching regulator, so I
thought it might be worth mentioning that linear technology have a free
download of "Switcher CAD", about a 2.8 Meg download.  This is based on
SPICE but includes a nice GUI with schematic capture.  It obviously is
designed to simulate Linears components, and includes models of all their
switcher IC's, but also has a reasonable library of other parts, and being
SPICE based should be easy to find other component models.  I'd be be
gratefull if you could pass the URL to the list:

    http://ltspice.linear.com/software/swcadiii.exe

I entered  your "divine switcher" schematic and although it clearly
"switched", the output waveforms were pretty horrendous (i.e. the 10 volt
output had 20 volt spikes on it).  I need to play a bit more as this is more
than likely down to the slightly suspicious component substitions I had to
make using the supplied library.

_____

Thanks for the reference - I'll try it.
I have a presumably older version of Switcher CAD but as far as I know it
doesn't do simulations.

The simulator may not perhaps like the pure inductor - I had problems with
these long ago with Spice. I don't know how this applied to the LT version.
Try adding a small resistance in series with the inductor - say 0r1 to 1r0.
In practice it is much better behaved than this.



regards


                Russell

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