Re: gEDA-user: ngspice and parts

["Harold D. Skank" <skank54@xxxxxxxxx>]

Harold Skank here.  I've been using ngspice heavily for the past
two/three weeks.  And when you start chasing SPICE models, you find that
licensing is definitely a vendor issue.  Not too surprising in that an
accurate SPICE model tells a whole lot about how a circuit is
engineered.  National Semiconductor has a HUGE file that packages many
of its products into one file.  For my part, I've found that I have to
pick that file apart to generate files that ngspice can use.  Fairchild,
on the other hand releases individual files for its semiconductors, but
requires that you acknowledge a license release before they e-mail your
first request.  In addition, almost all vendor SPICE files have license
headers in the individual files.

	Harold Skank

On Wed, 2005-07-27 at 22:55 +0200, Svenn Are Bjerkem wrote:
> On Thursday 07 July 2005 16:02, Stuart Brorson wrote:
> > Generating a SPICE model or .subckt from the datasheet is
> > difficult, and best left to experts.  It requires understanding
> > enough about the guts of SPICE to be able to know what all the
> > parameters mean.
> 
> Not to forget that many of the SPICE models are macro models even if 
> there is a built in version of the same element. (In the case of a 
> simple diode.) And for the LM317 you will have to know a lot about 
> the internal in order to write the macro model.
> 
> Luckily many semiconductor manufacturer offer models. That they are 
> not distributed with geda or ngspice may have something to do with 
> their licencing.