Re: Wanted: LM-709 (Spice model) National Op-Amp

Wow.  What a thread.  Well, since I am a pal with both
Bob Pease and Marcello, the guy that gets out National's
SPICE models I suppose I should toss in my two cents.

First, save any effort in contacting National.
We have better things to do then make SPICE models
for 30-year-old parts.  It is interesting that just tonight
I was telling Bill Gross and Tim Regen from LT how the
709 was noisy-- I thought I had heard it from Pease
but Bill corrected me--the 741 was noisy, the 709 was
actually pretty good.  And yeah, that is what Pease said
as well, I am geting old.

Next, it looks like a simple Google search would have
turned up something but thanks for this little tempest.

Next, there is a huge disconnect with people that use SPICE
for board-level and with people that use SPICE for IC design.
Yeah, just buy a UNIX workstation ($20k) buy Cadence (150k++)
and then run two departments-- one called "Process" and one
called "Modeling" ($5-10M) and yup, after 5 years or so you
will be able to get good results from SPICE.  God bless you.

And, if you buy PSPICE for 10k and still spend the 5 or 10 million
those two departments, the modeling and process departments, you
can still get good results for transistor-level simulation.  Linear Tech
uses PSPICE for IC design.  I have been told that LT-Cad is just a
variant of PSPICE so I am somewhat baffled how people can claim it
works "better".

But, PSPICE will still have trouble converging and doing things with fast
edges or digital (mixed signal) stuff.  That may be why National does not
release A to D converter SPICE models.  Now with the transistor-level
models, Cadence and a weekend to run, an A to D can yield to SPICE, I
suspect that Thompson guy gets things to work.

But now I leave you IC designers.. .if you want, I can post the twenty
pages of emails I traded with Barrie Gilbert of Analog Devices over this
exact subject.

For board-level SPICE you have to be very careful.  National's recent models
are very good.  We even model noise-- just watch the Pease Show
(now called "Analog by Design") in a week or two.  We just taped it yesterday.
We will show how you can check your models to see if the noise shows up
like in the real world.  We will show National's WEBENCH filter designer SPICE
exactly matching Electronics Workbench MultiSim8 SPICE and a real-world
board I built, all agreeing within 1/2 dB.  At 10kHz.  Next I will build a
15MHz filter.  That one will not do so well because all my board
strays will start effecting the circuit.  Stay tuned.

But if you are pushing the edge (and why would you need to do
SPICE if you weren't), well, you better be very good to understand
all the limitations of board-level SPICE.  You have to make sure
you have good models and test the models against the real world.
Next you have to model the board level stuff.  Maybe buy Hyperlynx,
the 48 grand 2 1/2 D field-solver to see trace interaction.
Maxwell's Equations are always right.  But you must build exact
3-D models of your circuit and have a lot of computer power.

And before you accuse Pease of being a hopeless curmudgeon, please
separate his "stage persona" from the real guy.  I have seen him
tell a young guy who asked about SPICE the perfect response-- use
it carefully and a little at first and build on your correlations to
allow you to SPICE more and more stuff.

And Bob may be a "kook" but he is a truly brilliant man.

So is Barrie Gilbert.

And Jim Thompson.

I just want to get them together in a WWF ring one day.

Now this has been a great thread and it raises some truly great
issues for us at National Semiconductor.  So when I go in tomorrow I
will be sure to get some answers to the question that seems most crucial:
"Bob, did you rally wear lederhausen in college?" And if the answer is
yes, "Were they lined with silk like the ones in the National Lampoon
Mr. Rogers' parody?"

Paul




Neil wrote: 
Looking for a spice model or subcircuit netlist for the LM709 from National semiconductor. I asked intusoft, cause they have a free model service. I bought their entry level software ICAP/4 8.3.3 from a dealer purchased in 2000. For reasons I won't mention, I was denied the request from their sales department.

I was going to email National, but from what I read in Bob's book "Troubleshooting Analog circuits" he doesn't like S.P.I.C.E. and for good reason...........:)

Any help on this request would be great....

Thanks Neil

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