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

[Neil]

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

 

[Kevin Aylward]

Neil wrote:

Looking for a spice model or subcircuit netlist for the LM709 from
National semiconductor.

Why?

Its a 30 year old part. No one in their right mind is going to use it.

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.

You have my sympathies.

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...........

He has no good reason. Spice is absolutely indispensable in analogue ic
design.

Those that don't use spice for general analogue design have simply
missed the boat. Times have moved on, unfortunately, it seems some
haven't.

Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Jim Thompson]

On 17 Sep 2005 01:10:35 -0700, "Neil" <neilwrites2@hotmail.com> 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

So why is it that Intusoft won't support you, and why is it that you
haven't E-mailed National?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Anton Erasmus]

On 17 Sep 2005 01:10:35 -0700, "Neil" <neilwrites2@hotmail.com> 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...........

From what I can recall of Bob's arguments against spice, was the same
as someone saying they do not like Word Processors, becuase they read
a badly written novel. If one uses SPICE incorrectly, then one gets
bogus results, if one understands it's limits and uses it correctly,
then it is a valuable tool.

Regards
Anton Erasmus

 

[Neil]

ha ha...ha, boat huh? you mean train don't you? Looks like your going
have to ask him(Robert Pease, National Engineer),he has spoke openly
about his views on spice at seminars accross United States, I read some
of his articles, I tend to agree. May be you should read the book I
mentioned in my POST, and make your own opinion. I use to trust spice
too.......... I own a few of the SPICE software programs, it's great
tool for learning, however......I'm sticking my original POST the
search for the model LM709

Yes, Kevin the part I admit is obselete, but believe it or not have a
few of these in my junk drawer in the T0-99 Pkge. Why ? Analog
Enginners love this kind of stuff, I very fond analog myself, I perfer
it over digital. Digital takes all the work, and fun out of
Electronics!!

Neil

 

[JeffM]

May be you should read the book I mentioned in my POST,
and make your own opinion.
Neil

Perhaps it was too subtle for you, so I'll highlight it for you.
http://groups.google.com/group/sci.electronics.cad/browse_frm/thread/fd9f4d78f037c5d1/c2037bd721acf107?q=anasoft+SuperSpice+Kevin-Aylward

Kevin is not only an engineer; not only a SPICE user;
he in fact PRODUCES a well-known variant.

Because he *maintains* it (read: bug reports),
he is very aware of the shortcommings of it
and he tweaks his software to adapt to those as they arise.

 

[Neil]

Well..........The sales manager says the software is too old and won't
work. Funny I thought most models work in SPICE 3F5, I don't
understand that either. Then the issue with the serial number, they
might not have a record of it anymore, but yet I talked to Bill several
times in California through email, and he always gave me support. The
dealer where I bought it from went out of business, so now Intusoft has
cut them loose, sort of speak, and ALL ICAP/4 products they sold to
their customers are not supported anymore.

I suspect the company is under new management, a real problem
especially if you purchased your software more then 5 years ago, I just
work with what I have, it's good enough for me!!

I won't email National for the SPICE model cause the part is obsolete,
but you can still buy them if your willing pay $10 bucks per
amp. I remember 4 years ago oilfield compaines were paying upwards of
over $30 dollars for a Harris HA-2520 Op-Amp..............very rare,
hard to find, and I have 2 in my parts drawer...........

Neil







Neil

 

[Neil]

True..............It seems SPICE has a world all of it's own in
analogue design, but one must follow the Rules of spice, and adapt..
Convergence is very fragile...................

Neil

 

[analog]

Neil wrote:

Looking for a spice model or subcircuit netlist for the LM709
from National semiconductor.

Why don't you just enter the equivalent schematic from the data
sheet (page 3 of the pdf - National 1995)? It only has thirteen
each of transistors and resistors (wouldn't take more than about
thirty minutes to get something up and running).

And why aren't you using Linear Technology's LTspice? It's free,
unlimited, completely general purpose and is faster and works
better than either Pspice or ICAP.

http://www.linear.com/company/software.jsp

Before I found LTspice I was a die-hard fan of Pspice (I have no
affiliation with Linear Technology, btw).

 

[Robert]

From what I can recall of Bob's arguments against spice, was the same
as someone saying they do not like Word Processors, becuase they read
a badly written novel. If one uses SPICE incorrectly, then one gets
bogus results, if one understands it's limits and uses it correctly,
then it is a valuable tool.

Regards
Anton Erasmus

Oh, it was a little more than that.

What he said finally drove him up a wall was he was trying to get a circuit
to converge with great frustration and IIRC he came in one morning and the
previous night's run had converged.

When he examined the netlist he found that he had (during the
troubleshooting effort) left in a couple of components (a resistor and
capacitor?) connected to ground with the other ends disconnected. They
should have had no effect on a real circuit.

That made it converge. Taking the components completely out of the circuit
caused the original non-convergence.

That kind of non-real World physical behavior, he calls it "lying", drives
him crazy.

Knowing a little bit about the algorithms of Spice I can perhaps guess that
leaving the circuit components in caused the circuit's Admittance Matrix to
be assembled in a not so ill conditioned State. But it would only be a
guess.

Robert

 

[Kevin Aylward]

Neil wrote:

ha ha...ha, boat huh? you mean train don't you? Looks like your going
have to ask him(Robert Pease, National Engineer),he has spoke openly
about his views on spice at seminars accross United States,

Yes, I know all about Bob. He is misguided on this.

I read
some of his articles, I tend to agree. May be you should read the
book I mentioned in my POST, and make your own opinion.

I have made my own opinion. Its based on being both an analogue ic and
board designer for er.. some years, and knowing how its actually done in
practise.

I use to

trust spice too..........

Of courses Spice has its limitations, just as a screwdriver does.
However, this doesn't mean that Spice shouldn't be used as the
fundamental design tool for analogue design.

You are obviously a newbie on this so I'll point out one or two issues.
Lets take analogue ic design. How do you propose to design a 1000
transistor circuit? A 10,000 transistor circuit? What's the fab cost?
Turn around time? You reckon that you can solve the equations by hand?

This is the deal. 10,000s of analogue ic designers, that is *all* of
them use spice as *the* number one de-facto method of designing
circuits. Period. It cant be any other way, today. Its simply not
possible to reliably design such circuits without spice. The designs are
two large and complex and cost too way much to fab. Its typically a 40
hour day, 5 days a week of solid simulation. This *is* the way it is.
Its quite common for people to design large analogue circuits, and have
them work 100% with first pass silicon. Some even get a $50k bonus on
that condition. Those that suggest that Spice is a side line tool, are
on a par to claiming that a Bible is just a superficial add-on to the
x-tian religion. They are quite oblivious to what practising analogue ic
designers use as a matter of course on a daily basis.

For the most part, designs don't work because of simply neglecting to do
a specific simulation, rather then the simulation itself not reflecting
real life. Its hard to think of all operating conditions. However, most
spices have various feature that allow worst case analysis to be
performed and other such multyruns. One might typically do 10,000
variations of a circuit. How do you propose to do such checking in the
real world?

Spice is like anything else, GIGO. Realistically, there is no
alternative. Even a 1 transistor circuit has no exact analytical
solution. The key is getting good models, and understanding the model
failings and compensating for that in the design.

Of course designs have to be physically checked on the bench, but if you
do know what you are doing this checking can be very, very, minimal.
Down to just producing a data sheet for example. I am sure Jim T. could
give us a few examples of right first time

Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Anton Erasmus]

On Sun, 18 Sep 2005 06:37:13 GMT, "Robert" <Robert@yahoo.com> wrote:

From what I can recall of Bob's arguments against spice, was the same
as someone saying they do not like Word Processors, becuase they read
a badly written novel. If one uses SPICE incorrectly, then one gets
bogus results, if one understands it's limits and uses it correctly,
then it is a valuable tool.

Regards
Anton Erasmus

Oh, it was a little more than that.

What he said finally drove him up a wall was he was trying to get a circuit
to converge with great frustration and IIRC he came in one morning and the
previous night's run had converged.

When he examined the netlist he found that he had (during the
troubleshooting effort) left in a couple of components (a resistor and
capacitor?) connected to ground with the other ends disconnected. They
should have had no effect on a real circuit.

That made it converge. Taking the components completely out of the circuit
caused the original non-convergence.

That kind of non-real World physical behavior, he calls it "lying", drives
him crazy.

Knowing a little bit about the algorithms of Spice I can perhaps guess that
leaving the circuit components in caused the circuit's Admittance Matrix to
be assembled in a not so ill conditioned State. But it would only be a
guess.

I think a great many (most ?) problems with SPICE and other simulation
programs in general are actually due to problems of the "Floating
Point" data type. AFAIK the total reason for being of the floating
point data type was to get a reasonable range and precision using as
little memory as possible. Today memory is not a problem anymore, and
one can use a fixed point number format with the desired range and
precision necessary for any simulation. A typical construct in many
simulations are:

(x0-x1)/k where x0 and x1 are almost equal. This causes problems in
floating point. If x0 an x1 are say 1.0 and 1.0001 then it is not a
problem. If it is 1000000000.0 and 1000000000.0001, then it bombs out.

I personally think that with todays systems, the use of floating point
should be banned, and in stead large fixed point numbers should be
used. The only disadvantage compared to floating point is that it uses
more memory. (And the little problem that almost no currently used
languages supports them as standard)

Regards
Anton Erasmus

 

[Stuart Brorson]

Neil <neilwrites2@hotmail.com> wrote:
: Well..........The sales manager says the software is too old and won't
: work.

[. . . .]

: I suspect the company is under new management, a real problem
: especially if you purchased your software more then 5 years ago, I just
: work with what I have, it's good enough for me!!

Heh. Another reason why open-source EDA tools are preferable over
secret-source ones: No obsolescence. In particular, no obsolescence
based upon stupid political or marketing considerations.

http://geda.seul.org/
http://ngspice.sourceforge.net/

SDB

 

[Stuart Brorson]

Robert <Robert@yahoo.com> wrote:
: What he said finally drove him up a wall was he was trying to get a circuit
: to converge with great frustration and IIRC he came in one morning and the
: previous night's run had converged.

: When he examined the netlist he found that he had (during the
: troubleshooting effort) left in a couple of components (a resistor and
: capacitor?) connected to ground with the other ends disconnected. They
: should have had no effect on a real circuit.

: That made it converge. Taking the components completely out of the circuit
: caused the original non-convergence.

: That kind of non-real World physical behavior, he calls it "lying", drives
: him crazy.

I'll add my $0.02 here; perhaps it is useful.

On the SPICE vs. no SPICE debate: Designing modern analog ICs [1]
would be well-neigh impossible without SPICE due to modern circuit
size and complexity. Other posters have already pointed this out.
Also, when designing an IC, you control nearly
all parameters of the components you use, and you have highly accurate
models of your transistors available. Therefore, SPICE can do a good
job predicting circuit behavior.

Designing analog boards, on the other hand, is different. Most of the
time, the models you have at your disposal are vendor macromodels,
which are not device-level models of the actual components you use.
Rather, they are idealizations which attempt to model the important
features of the device's performance in its operating region.
Vendors won't give you real device-level models of their components
because then you could reverse-engineer their circuits. Therefore,
the SPICE models you use in board design are generally useful, but are
not totally accurate.

Also, when designing boards, stray capacitances are not as well
understood or controlled as they are when designing ICs. (Perhaps if
you purchase a $100K tool from one of the big EDA vendors you can
extract the strays from a PCB layout, but I have never seen that done
in real life.) Therefore, the fabbed board will always act
differently from any SPICE simulation, particularly if your circuit is
sensitive to strays.

Therefore, for IC design, SPICE is indespensible. For board
design SPICE provides good guidance, but isn't the last word in
predicting circuit performance.

As for the issue of convergence mentioned above: My experience is
that if your SPICE simulation behaves strangely or doesn't converge,
it is likely that you have a fundamental problem with your circuit.
When a circuit doesn't converge, besides looking for floating nodes, I
always examine my circuit thoroughly looking for subtle mess-ups such
as two different current sources in series, or two different voltage
sources in parallel. More often than not, I find that I have
committed some kind of error.

Stuart

[1] Note bene: I am not an IC designer, so others can speak with
more authority about this. Nonetheless, my point is general enough to
not require detailed, expierential knowledge of IC design.

 

[Helmut Sennewald]

"Neil" <neilwrites2@hotmail.com> schrieb im Newsbeitrag
news:1126944635.562276.150550@g44g2000cwa.googlegroups.com...

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

Hello Neil,

If you look with Google (uA709 spice) then you will find two
sources for a model.
One is in the library file "opamp.lib" from Microsim/Cadence.
It's a very old behavioral model and I have not tested it.
I don't have a PSPICE license and so I don't would use it.

In this "summer2000.pdf" is a netlist of a test circuit with
the LM/uA709. It's nothing else than an exact copy of the
schematic of the LM709 from National's datasheet.
http://www.spectrum-soft.com/down/summer2000.pdf

http://www.national.com/ds.cgi/LM/LM709.pdf

I used this datasheet and made my own model. I would be
interested to get some feedback about the parameters of my
"invented" transistor models. I have used the reference
designators from the the datasheet to make it easier to
modify the model if necessary.
THe model agrees very well with the performance of the datasheet.
It's a free model. Feel free to use/copy/modify.

I have also made a complete example for LTspice with
a schematic based on a nice symbol and a model file.
Additionally I have made a hierachical block design
which allows to probe down the hierarchy (in the schematic)
to every node of the LM709.

LTspice is free SPICE from www.linear.com .
http://ltspice.linear.com/software/swcadiii.exe

The LTspice user group:
http://groups.yahoo.com/group/LTspice

Download the files from here within the Yahoo group.

Files > Lib > LM709_uA709

Best regards,
Helmut




* LM709 SPICE Model
* Datasheet: http://www.national.com/ds.cgi/LM/LM709.pdf
* Helmut Sennewald
*
* Input compensation B (8) --------------------\
* Input compensation A (1) -----------------\ |
* Output compensation (5) --------------\ | |
* Output (6) -----------------------\ | | |
* Negative supply (4) ----------\ | | | |
* Positive supply (7) -------\ | | | | |
* Inverting input (2) ----\ | | | | | |
* non-inverting input(3) | | | | | | |
* | | | | | | | |
..subckt LM709 In+ In- V+ V- OUT COMP A B
Q7 v+ N001 N005 0 NPN1
R5 v+ N001 10k
Q3 N001 N006 N003 0 NPN1
Q4 N001 N003 N002 0 NPN1
R1 N005 N006 25k
R3 N003 N004 3k
Q15 N004 N004 N002 0 NPN1
R2 N005 A 25k
Q2 A in- N007 0 NPN1
Q1 N006 in+ N007 0 NPN1
Q5 B A N009 0 NPN1
R4 N009 N004 3k
Q6 B N009 N002 0 NPN1
R6 v+ B 10k
R8 N002 N011 3.6k
R10 N011 N010 10k
Q10 N010 N010 V- 0 NPN1
Q11 N007 N010 N008 0 NPN1
R11 N008 V- 2.4k
R9 N012 N011 10k
Q8 v+ B N013 0 NPN1
R7 N013 N012 1k
Q9 comp N002 N012 0 PNP1
R13 N014 V- 75
R12 comp N014 10k
Q12 N015 comp N014 0 NPN1
Q13 V- N015 out 0 PNP1
Q14 v+ N015 out 0 NPN1
R14 v+ N015 20k
R15 N012 out 30k
..MODEL NPN1 NPN (BF=100 VAF=50 RB=100 CJE=4P CJC=2P CJS=2P TF=0.5N TR=10N)
..MODEL PNP1 PNP (BF=15 VAF=50 CJC=4P CJE=8P RB=100 TF=20N TR=200N)
..ends LM709

 

[Robert]

"Stuart Brorson" <sdb@cloud9.net> wrote in message
news:11iqrok1ae4pbe7@corp.supernews.com...

Robert <Robert@yahoo.com> wrote:
: What he said finally drove him up a wall was he was trying to get a
circuit
: to converge with great frustration and IIRC he came in one morning and
the
: previous night's run had converged.

: When he examined the netlist he found that he had (during the
: troubleshooting effort) left in a couple of components (a resistor and
: capacitor?) connected to ground with the other ends disconnected. They
: should have had no effect on a real circuit.

: That made it converge. Taking the components completely out of the
circuit
: caused the original non-convergence.

: That kind of non-real World physical behavior, he calls it "lying",
drives
: him crazy.

I'll add my $0.02 here; perhaps it is useful.

On the SPICE vs. no SPICE debate: Designing modern analog ICs [1]
would be well-neigh impossible without SPICE due to modern circuit
size and complexity. Other posters have already pointed this out.
Also, when designing an IC, you control nearly
all parameters of the components you use, and you have highly accurate
models of your transistors available. Therefore, SPICE can do a good
job predicting circuit behavior.

Designing analog boards, on the other hand, is different. Most of the
time, the models you have at your disposal are vendor macromodels,
which are not device-level models of the actual components you use.
Rather, they are idealizations which attempt to model the important
features of the device's performance in its operating region.
Vendors won't give you real device-level models of their components
because then you could reverse-engineer their circuits. Therefore,
the SPICE models you use in board design are generally useful, but are
not totally accurate.

[snip]

As for the issue of convergence mentioned above: My experience is
that if your SPICE simulation behaves strangely or doesn't converge,
it is likely that you have a fundamental problem with your circuit.
When a circuit doesn't converge, besides looking for floating nodes, I
always examine my circuit thoroughly looking for subtle mess-ups such
as two different current sources in series, or two different voltage
sources in parallel. More often than not, I find that I have
committed some kind of error.

Stuart

[1] Note bene: I am not an IC designer, so others can speak with
more authority about this. Nonetheless, my point is general enough to
not require detailed, expierential knowledge of IC design.

Yes your point is general and has nothing to do with what I said.

Two passive components, a resistor and a cap, left in a netlist connected
to ground WITH the other end disconnected causes a circuit to converge when
without them it does not. Bob went on to say (tongue in cheek?) that perhaps
non-functioning components strewn randomly through a design could be an add
on Spice convergence feature.

That does not have anything to do with the type of errors you mentioned. And
the existence of such a problem points to deeper problems with Spice than
you mention.

It is quite possible it was a problem with an early Spice Algorithm in how
the numbers were crunched (ill conditioned Matrix were favorite weasel words
at one time).

Wouldn't know. Would know that the problem (if it is as I remembered) has
nothing to do with the problems you mention.

Robert

 

[Jim Thompson]

On Sun, 18 Sep 2005 21:02:25 GMT, "Robert" <Robert@yahoo.com> wrote:

[snip]

Two passive components, a resistor and a cap, left in a netlist connected
to ground WITH the other end disconnected causes a circuit to converge when
without them it does not. Bob went on to say (tongue in cheek?) that perhaps
non-functioning components strewn randomly through a design could be an add
on Spice convergence feature.

Though Bob Pease is a fellow classmate of mine at MIT, he is very
often quite full of it... a good portion of what he propounds is just
plain urban legend BS.

The way he typically spouts I often wonder if he's ever used Spice at
all.

That does not have anything to do with the type of errors you mentioned. And
the existence of such a problem points to deeper problems with Spice than
you mention.

A good simulator will report floating nodes.

It is quite possible it was a problem with an early Spice Algorithm in how
the numbers were crunched (ill conditioned Matrix were favorite weasel words
at one time).

Wouldn't know. Would know that the problem (if it is as I remembered) has
nothing to do with the problems you mention.

Robert

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Robert]

"Jim Thompson" <thegreatone@example.com> wrote in message
news:aksri1p5jplv8n72iioc2qqauvbvgi0fiu@4ax.com...

On Sun, 18 Sep 2005 21:02:25 GMT, "Robert" <Robert@yahoo.com> wrote:

[snip]

Two passive components, a resistor and a cap, left in a netlist connected
to ground WITH the other end disconnected causes a circuit to converge
when
without them it does not. Bob went on to say (tongue in cheek?) that
perhaps
non-functioning components strewn randomly through a design could be an
add
on Spice convergence feature.

Though Bob Pease is a fellow classmate of mine at MIT, he is very
often quite full of it... a good portion of what he propounds is just
plain urban legend BS.

Sure. But I don't think he got such simple details wrong. And I don't think
he was just making up a story. Possible, but not likely.

The way he typically spouts I often wonder if he's ever used Spice at
all.


That does not have anything to do with the type of errors you mentioned.
And
the existence of such a problem points to deeper problems with Spice than
you mention.

A good simulator will report floating nodes.

Who said he had a good simulator? I imagine it was a company version of
Spice from back in the days when they were still working the kinks out. If
you want I can dig up the reference from my old copy of his book.

Robert

 

[Stuart Brorson]

Robert <Robert@yahoo.com> wrote:
: "Stuart Brorson" <sdb@cloud9.net> wrote in message
[ . . . .]
: news:11iqrok1ae4pbe7@corp.supernews.com...
:> As for the issue of convergence mentioned above: My experience is
:> that if your SPICE simulation behaves strangely or doesn't converge,
:> it is likely that you have a fundamental problem with your circuit.
:> When a circuit doesn't converge, besides looking for floating nodes, I
:> always examine my circuit thoroughly looking for subtle mess-ups such
:> as two different current sources in series, or two different voltage
:> sources in parallel. More often than not, I find that I have
:> committed some kind of error.
[. . . .]

: Yes your point is general and has nothing to do with what I said.

: Two passive components, a resistor and a cap, left in a netlist connected
: to ground WITH the other end disconnected causes a circuit to converge when
: without them it does not. [. . . .]

You are dead wrong. Here's what I wrote above:

:> When a circuit doesn't converge, besides looking for floating
:> nodes . . . . More often than not, I find that I have
:> committed some kind of error.

A cap connected to GND with the other end open is a floating node.
Avoiding floating nodes is SPICE 101 knowledge.

In any line of work, if you want to use a tool, then you need to have
some idea about how it works. Or do you use a hammer to pound screws?

: That does not have anything to do with the type of errors you mentioned. And
: the existence of such a problem points to deeper problems with Spice than
: you mention.

My point is that SPICE is only as good as the models you use. The
models used for IC design are pretty good, whereas those used for
board design are useful but limited.

Your arguments about the problems with SPICE are vague,
general, and aren't based on any detailed knowledge of SPICE's methods
and limitations that I can see. They seem to be more of an objection
to computer simulation, and your only evidence is the opinion of Bob
Pease (whose job it is to make outre claims as part of
National's marketing effort). If you do have something specific and
knowledgable about SPICE's limitations to say, I'd be interested in
hearing it. Otherwise, I'll bid this thread adieu.

Anyway, you are welcome to not use SPICE in your design work -- if you
do design at all. Personally, I would like to see you explain to a
job interviewer that you are an electronics engineer who refuses to
use SPICE! *snort*

Stuart

 

[BruceR]

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

Hi Neil,

I was just looking through the samples that came with MicroCap 6.0.8
(w32) and found UA709.CIR & UA709.CKT. Perhaps these are what you want?

Regards, BruceR