Problems with SPICE models from vendors

In article <TzC1e.14264$4%3.11949@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:

I suppose you want the moon on a stick as well.
Click to expand...
Hmm... Nice bit of selective editing.

I'll just repeat the paragraph you cut out
in order to make your snide little remark.

"If given the part numbers I don't mind calling
up LT devices as 'payment' for LTspice."

--
Tony Williams.
 
Tony Williams wrote:
In article <TzC1e.14264$4%3.11949@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:

I suppose you want the moon on a stick as well.

Hmm... Nice bit of selective editing.

I'll just repeat the paragraph you cut out
in order to make your snide little remark.
Click to expand...
It wasn't "snide".

"Just to add to the LTspice wish-list" was what the comment was directed
at. Snipping the following bit changed nothing.

"If given the part numbers I don't mind calling
up LT devices as 'payment' for LTspice."
Click to expand...
As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software products,
but my expectations of what I get for my money are rather limited. Any
"little" feature, can end up being a massive amount of work.

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.
 
Tony Williams wrote:

In article <ltp1e.5675$H06.1598@newsread3.news.pas.earthlink.net>,
Robert Baer <robertbaer@earthlink.net> wrote:


Using LTspice solved the problem.


However, it *would* be of great use if:

[snip]

Just to add to the LTspice wish-list........

An automatic cross-reference between opamp and
comparator part numbers and LT's own devices.

eg, select "TL081" from the list, but get given
the nearest LT device..... LTxxxx if an exact
pin for pin equivalent, (LTxxxx) if it is a
nearly but not quite equivalent.

If given the part numbers I don't mind calling
up LT devices as 'payment' for LTspice.

Excellent additions.
Click to expand...
In using LTspice somemore, i add:
The output be in the same *order* that one has in the .PRINT statement.
 
Kevin Aylward wrote:

Tony Williams wrote:

In article <TzC1e.14264$4%3.11949@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:


I suppose you want the moon on a stick as well.

Hmm... Nice bit of selective editing.

I'll just repeat the paragraph you cut out
in order to make your snide little remark.


It wasn't "snide".

"Just to add to the LTspice wish-list" was what the comment was directed
at. Snipping the following bit changed nothing.


"If given the part numbers I don't mind calling
up LT devices as 'payment' for LTspice."


As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software products,
but my expectations of what I get for my money are rather limited. Any
"little" feature, can end up being a massive amount of work.

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.


...don't snile when you can smarl?
Click to expand...
 
In article <QdO1e.17494$4%3.5551@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:
[snip]
As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software
products, but my expectations of what I get for my money are
rather limited. Any "little" feature, can end up being a massive
amount of work.
Click to expand...
You still don't see it.

It's a suggestion that could be beneficial to LT.

At rock bottom, LTspice is an aid to selling Linear
Technology's products. The suggestion of a cross
reference between other mfr's products and equivalent
LT devices is intended to help LTspice to sell more
LT devices.

I repeat: If in LTspice I called up say a TL081,
and got offered a similar LT device, then I would
simulate with that and probably call up the LT device
in the final BOM. That seems a fair way of 'paying'
for what is an excellent free piece of software.

--
Tony Williams.
 
"Tony Williams" <tonyw@ledelec.demon.co.uk> schrieb im Newsbeitrag
news:4d52a29efatonyw@ledelec.demon.co.uk...
In article <QdO1e.17494$4%3.5551@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:
[snip]
As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software
products, but my expectations of what I get for my money are
rather limited. Any "little" feature, can end up being a massive
amount of work.

You still don't see it.

It's a suggestion that could be beneficial to LT.

At rock bottom, LTspice is an aid to selling Linear
Technology's products. The suggestion of a cross
reference between other mfr's products and equivalent
LT devices is intended to help LTspice to sell more
LT devices.

I repeat: If in LTspice I called up say a TL081,
and got offered a similar LT device, then I would
simulate with that and probably call up the LT device
in the final BOM. That seems a fair way of 'paying'
for what is an excellent free piece of software.

--
Tony Williams.
Click to expand...
Hello Tony,
the benfit for LT would be low. LTspice tries to make
"unique" opamps. Unique means they have one or more
better specs than you get from standard parts.
This may result in a higher price for such better parts.
If people have the cheapest parts of the world (TL082)
in mind, they can't afford anything more expensive.

It's so simple to add any third party model. The only
additional thing to do is adding a ".include" command line.
You don't need a new symbol for every other opamp!

1. Add the "opamp2" symbol.
2. Rename it the model name(opamp2) in the schematic,
e.g. opamp2 to TL082 .
3. Add this command line: .include model_file_name
4. Place the model_file in the directory where you have
saved the schematic.

Best Regards,
Helmut

PS: I am not an employee of LT if that matters.
 
Tony Williams wrote:
In article <QdO1e.17494$4%3.5551@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:
[snip]
As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software
products, but my expectations of what I get for my money are
rather limited. Any "little" feature, can end up being a massive
amount of work.

You still don't see it.
Click to expand...
Oh?

It's a suggestion that could be beneficial to LT.
Click to expand...
It may well be, but its a return on investment. *How* beneficial would
it be to LT?

At rock bottom, LTspice is an aid to selling Linear
Technology's products. The suggestion of a cross
reference between other mfr's products and equivalent
LT devices is intended to help LTspice to sell more
LT devices.

I repeat: If in LTspice I called up say a TL081,
and got offered a similar LT device, then I would
simulate with that and probably call up the LT device
in the final BOM. That seems a fair way of 'paying'
for what is an excellent free piece of software.
Click to expand...
I also repeat "Any little feature, can end up being a massive amounts of
work."

I've been there dude, I am still there. Sure, lots of things may be
"useful". Whether or not it makes any business sense to do so is another
matter. LTSpice is still only an *indirect* way to generate revenue.
Maybe it could be cost effective to add more bells and whistles, but the
impression I got was still this "looking a gift horse in the mouth" sort
of thing. I suppose you also want fries with that?

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.
 
In article <FoR1e.18312$4%3.15162@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:
huge snip]
I've been there dude, I am still there. Sure, lots of things may
be "useful". Whether or not it makes any business sense to do so
is another matter. LTSpice is still only an *indirect* way to
generate revenue. Maybe it could be cost effective to add more
bells and whistles, but the impression I got was still this
"looking a gift horse in the mouth" sort of thing. I suppose you
also want fries with that?
Click to expand...
You can of course conveniently ignore any of the other
posts I have made praising/recommending LTspice.

--
Tony Williams.
 
On Mon, 28 Mar 2005 10:55:33 GMT, "Kevin Aylward"
<see_website@anasoft.co.uk> wrote:

I suppose you also want fries with that?
Click to expand...
Sure. That would be a good feature.

But not too often. Got a good model for my cholesterol with/without?
 
Tony Williams wrote:

In article <QdO1e.17494$4%3.5551@fe2.news.blueyonder.co.uk>,
Kevin Aylward <see_website@anasoft.co.uk> wrote:
[snip]

As a realist, I would never even contemplate a "wish" of what you
suggested for a freebee product. I certainly use free software
products, but my expectations of what I get for my money are
rather limited. Any "little" feature, can end up being a massive
amount of work.


You still don't see it.

It's a suggestion that could be beneficial to LT.

At rock bottom, LTspice is an aid to selling Linear
Technology's products. The suggestion of a cross
reference between other mfr's products and equivalent
LT devices is intended to help LTspice to sell more
LT devices.

I repeat: If in LTspice I called up say a TL081,
and got offered a similar LT device, then I would
simulate with that and probably call up the LT device
in the final BOM. That seems a fair way of 'paying'
for what is an excellent free piece of software.

And it is not difficult to do, it just takes time.
Click to expand...
So one mfg's product could be used as a starter, and others can be
added on as time permits.
An excellent initial candidate for replacement look-up is Maxim, as
the majority of what they advertise is vaporware, and un-buidable
articles causes frustration and excellent candidates as customers for
parts that !can! be obtained.
 
<zineddine.zidane@gmail.com> schrieb im Newsbeitrag
news:1111793144.550277.241490@f14g2000cwb.googlegroups.com...
Hmm useless huh? the AD8614 has 1mV of Vos and the model has 1mV, I
just looked at it, so I don't know what you mean by not working. I
think you may be overlooking some things here. Here's the Vos in the
netlist...
EOS 7 1 POLY(2) (73,98) (81,98) 1E-3 1 1
Click to expand...
Hello zidane,

Robert was especially disappointed about the bias current.
It is modeled with about 700nA.
The datasheet shows max. Ib=400nA.
It's a valid question why Ib is modelled not with the typical values.
The later curves in the datasheet show Ib=300nA.
I am talking about Ib when Vin is near the supply rails.
Maybe you can enlighten us about the bias current.

I agree with your typical Vos of 1mV.

Best Regards,
Helmut
 
Kevin Aylward wrote:

Tony Williams wrote:

In article <ltp1e.5675$H06.1598@newsread3.news.pas.earthlink.net>,
Robert Baer <robertbaer@earthlink.net> wrote:


Using LTspice solved the problem.

However, it *would* be of great use if:

[snip]

Just to add to the LTspice wish-list........

An automatic cross-reference between opamp and
comparator part numbers and LT's own devices.

eg, select "TL081" from the list, but get given
the nearest LT device..... LTxxxx if an exact
pin for pin equivalent, (LTxxxx) if it is a
nearly but not quite equivalent.




I suppose you want the moon on a stick as well.

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.


That is not within the confines of SPICE in general, so talk to NASA...
Click to expand...
 
hello folks, just saw your message about my Spice models. I did the
AD8605 model and would like to know what it is that you think isn't
working. I would prefer to see the test circuit you're using and
understand what you're trying to do. And if it really doesn't work,
then I owe you a pizza of your choice.






Helmut Sennewald wrote:
"Robert Baer" <robertbaer@earthlink.net> schrieb im Newsbeitrag
news:1PQ0e.3481$gI5.1145@newsread1.news.pas.earthlink.net...
The LM324 model from TI works fine,but the one from National
Semiconductor is junk.
I tried numerous Analog Devices models for various rail-to-rail
opamps,
and found that almost all i tried gave me the same kind of cryptic
square
root error.
Those tried: AD8605, AD531, AD541, AD8552, and the AD8571; the
only one
tried that did work was for the AD8614.
Now i would dearly like to have a set of models that were known
to work
(and more or less correctly), but i need to get a working AD8605
model.
The sets i have came from the manufacturer created in the latter
of
1992, and thus are not quite up-to-date.
However, the model for the AD8605 was downloaded via the web just

yesterday - implying the problem is not fixed.

Can anyone help?

Hello Robert,
I don't believe that you really can judge the quality of these
models as a beginner with SPICE simulations.
I agree with you that most models have difficulties with convergence.
Many of them are really over complicated and sometimes generated
by stupid programs or "roboters" and not by engineers.

I assume that the listed models will work with some tweaking
of the convergence parameters.

What simulator do you use?
If it's LTspice then send me your files and I will make
you a working example with your AD8605.
I always want to see the schematic, because I know that
people sometimes have errors in their circuit.
One important thing is to have a DC path to ground(0).


Best Regards,
Helmut
Moderator of the LTspice user group
Click to expand...
 
Hello Helmut:
I got an email from a colleague informing of the problem and didn't see
your response on the board.





zineddine.zidane@gmail.com wrote:
hello folks, just saw your message about my Spice models. I did the
AD8605 model and would like to know what it is that you think isn't
working. I would prefer to see the test circuit you're using and
understand what you're trying to do. And if it really doesn't work,
then I owe you a pizza of your choice.






Helmut Sennewald wrote:
"Robert Baer" <robertbaer@earthlink.net> schrieb im Newsbeitrag
news:1PQ0e.3481$gI5.1145@newsread1.news.pas.earthlink.net...
The LM324 model from TI works fine,but the one from National
Semiconductor is junk.
I tried numerous Analog Devices models for various rail-to-rail
opamps,
and found that almost all i tried gave me the same kind of
cryptic
square
root error.
Those tried: AD8605, AD531, AD541, AD8552, and the AD8571; the
only one
tried that did work was for the AD8614.
Now i would dearly like to have a set of models that were known
to work
(and more or less correctly), but i need to get a working AD8605
model.
The sets i have came from the manufacturer created in the
latter
of
1992, and thus are not quite up-to-date.
However, the model for the AD8605 was downloaded via the web
just

yesterday - implying the problem is not fixed.

Can anyone help?

Hello Robert,
I don't believe that you really can judge the quality of these
models as a beginner with SPICE simulations.
I agree with you that most models have difficulties with
convergence.
Many of them are really over complicated and sometimes generated
by stupid programs or "roboters" and not by engineers.

I assume that the listed models will work with some tweaking
of the convergence parameters.

What simulator do you use?
If it's LTspice then send me your files and I will make
you a working example with your AD8605.
I always want to see the schematic, because I know that
people sometimes have errors in their circuit.
One important thing is to have a DC path to ground(0).


Best Regards,
Helmut
Moderator of the LTspice user group
Click to expand...
 
Hmm useless huh? the AD8614 has 1mV of Vos and the model has 1mV, I
just looked at it, so I don't know what you mean by not working. I
think you may be overlooking some things here. Here's the Vos in the
netlist...
EOS 7 1 POLY(2) (73,98) (81,98) 1E-3 1 1





Robert Baer wrote:
Helmut Sennewald wrote:
"Robert Baer" <robertbaer@earthlink.net> schrieb im Newsbeitrag
news:1PQ0e.3481$gI5.1145@newsread1.news.pas.earthlink.net...

The LM324 model from TI works fine,but the one from National
Semiconductor is junk.
I tried numerous Analog Devices models for various rail-to-rail
opamps,
and found that almost all i tried gave me the same kind of cryptic
square
root error.
Those tried: AD8605, AD531, AD541, AD8552, and the AD8571; the
only one
tried that did work was for the AD8614.
Now i would dearly like to have a set of models that were known
to work
(and more or less correctly), but i need to get a working AD8605
model.
The sets i have came from the manufacturer created in the latter
of
1992, and thus are not quite up-to-date.
However, the model for the AD8605 was downloaded via the web just

yesterday - implying the problem is not fixed.

Can anyone help?


Hello Robert,
I don't believe that you really can judge the quality of these
models as a beginner with SPICE simulations.
I agree with you that most models have difficulties with
convergence.
Many of them are really over complicated and sometimes generated
by stupid programs or "roboters" and not by engineers.

I assume that the listed models will work with some tweaking
of the convergence parameters.

What simulator do you use?
If it's LTspice then send me your files and I will make
you a working example with your AD8605.
I always want to see the schematic, because I know that
people sometimes have errors in their circuit.
One important thing is to have a DC path to ground(0).


Best Regards,
Helmut
Moderator of the LTspice user group




Well, in a sense you are correct in labellling be as a beginner; i

rarely use SPICE, but that useage has covered over 30 years.
When one models a simple voltage follower, with the NI input half
way
between the poser supplies for the op-amp, one expects it to work,
and
not give a cryptic square root error.
Furthermore, replacing the model used to a different one (eg
replace
the call from the AD8605 to the AD8614 (and changing *nothing* else)
and
have it work begs the question: what is wrong with the AD8605 model?
The same can be said about the models for the LM324; the TI model
works and the NatSemi does not.

And speaking of bad models that DO "work", the AD8614 is rather
poor
(from the .OUT file):

.OPTIONS ACCT LIST NODE OPTS NUMDGT=6 RELTOL=0.00001 NOPAGE
.TEMP 27
.LIB ANLG_DEV.LIB ; most rail-to-rail opamps die with error
.DC VBAT 4.499 4.501 0.001
VBAT 01 00 DC 4.5
VSET 10 00 0.209171
VIN 05 00 0.018051
R2 05 07 18.4K
R3 10 08 18.4K
R4 09 07 100K
* NI I OUT
XAMP2 08 07 01 00 09 AD8614/AD
.PRINT DC V(05) V(07) V(08) V(09)
.PLOT DC V(05) V(07) V(08) V(09)
.SAVE

V(5) V(7) V(8) V(9)

1.80510E-02 2.22746E-01 2.21746E-01 1.26487E+00

Look at the poor results: large input currents, large Vos. Almost

useless; certainly not representative of the part.
Click to expand...
 
zineddine.zidane@gmail.com wrote:

Hmm useless huh? the AD8614 has 1mV of Vos and the model has 1mV, I
just looked at it, so I don't know what you mean by not working. I
think you may be overlooking some things here. Here's the Vos in the
netlist...
EOS 7 1 POLY(2) (73,98) (81,98) 1E-3 1 1





Robert Baer wrote:

Helmut Sennewald wrote:

"Robert Baer" <robertbaer@earthlink.net> schrieb im Newsbeitrag
news:1PQ0e.3481$gI5.1145@newsread1.news.pas.earthlink.net...


The LM324 model from TI works fine,but the one from National
Semiconductor is junk.
I tried numerous Analog Devices models for various rail-to-rail

opamps,

and found that almost all i tried gave me the same kind of cryptic

square

root error.
Those tried: AD8605, AD531, AD541, AD8552, and the AD8571; the

only one

tried that did work was for the AD8614.
Now i would dearly like to have a set of models that were known

to work

(and more or less correctly), but i need to get a working AD8605

model.

The sets i have came from the manufacturer created in the latter

of

1992, and thus are not quite up-to-date.
However, the model for the AD8605 was downloaded via the web just


yesterday - implying the problem is not fixed.

Can anyone help?


Hello Robert,
I don't believe that you really can judge the quality of these
models as a beginner with SPICE simulations.
I agree with you that most models have difficulties with

convergence.

Many of them are really over complicated and sometimes generated
by stupid programs or "roboters" and not by engineers.

I assume that the listed models will work with some tweaking
of the convergence parameters.

What simulator do you use?
If it's LTspice then send me your files and I will make
you a working example with your AD8605.
I always want to see the schematic, because I know that
people sometimes have errors in their circuit.
One important thing is to have a DC path to ground(0).


Best Regards,
Helmut
Moderator of the LTspice user group





Well, in a sense you are correct in labellling be as a beginner; i


rarely use SPICE, but that useage has covered over 30 years.
When one models a simple voltage follower, with the NI input half

way

between the poser supplies for the op-amp, one expects it to work,

and

not give a cryptic square root error.
Furthermore, replacing the model used to a different one (eg

replace

the call from the AD8605 to the AD8614 (and changing *nothing* else)

and

have it work begs the question: what is wrong with the AD8605 model?
The same can be said about the models for the LM324; the TI model
works and the NatSemi does not.

And speaking of bad models that DO "work", the AD8614 is rather

poor

(from the .OUT file):

.OPTIONS ACCT LIST NODE OPTS NUMDGT=6 RELTOL=0.00001 NOPAGE
.TEMP 27
.LIB ANLG_DEV.LIB ; most rail-to-rail opamps die with error
.DC VBAT 4.499 4.501 0.001
VBAT 01 00 DC 4.5
VSET 10 00 0.209171
VIN 05 00 0.018051
R2 05 07 18.4K
R3 10 08 18.4K
R4 09 07 100K
* NI I OUT
XAMP2 08 07 01 00 09 AD8614/AD
.PRINT DC V(05) V(07) V(08) V(09)
.PLOT DC V(05) V(07) V(08) V(09)
.SAVE

V(5) V(7) V(8) V(9)

1.80510E-02 2.22746E-01 2.21746E-01 1.26487E+00

Look at the poor results: large input currents, large Vos. Almost


useless; certainly not representative of the part.


Ok, i am convinced that the AD8614 was a lousy choice - but it was
Click to expand...
the only rail-to-rail model that worked at that time.
I have downloaded SwitcherCAD3 and have part of my circuit working
using the AD8605 model.
So it is clear that there is something about those
non-working-for-TopSpice models that goof it up, but is allowed in the
more modern SPICE programs.
That said, the results i get are WRONG - essentially it is saying
that 1+1 is not 2.
I could attach the .ASC file, but it is fairly large (about 4K), and
tell you what the node voltages SC3 gives.
Let me do it the quick way; SC3 sez:
N003 at 0.295mV; R2=18.2K from N003 to N007 at 0.188481V; op amp NI
at N006, I at N007, output at N008, V- at gnd, v+ at 4.5V; feedback
R4=100K from N006 to N007; N006 at 0.188571V; I(R2)=I(R4)=10.3399uA;
N008=0.376666V.

But do the calcs by hand; I(R2) = (0.188481V-0.000295V)/(18.2K) =
0.0103398mA. Drop across 100k then is 1.03398V; add to voltage at N007
for calc(N008)=1.222461V.

Therefore 1+1=2 and Spice is whistling Dixie.
 
In article <d28mtn$mm9$02$1@news.t-online.com>,
Helmut Sennewald <helmutsennewald@t-online.de> wrote:

Hello Tony,
the benfit for LT would be low. LTspice tries to make
"unique" opamps. Unique means they have one or more
better specs than you get from standard parts.
Click to expand...
Hmm... perhaps that is why the Linear View 3 CDROM
(which I bought as a result of LTspice) also does not
carry any cross references.

This may result in a higher price for such better parts.
If people have the cheapest parts of the world (TL082)
in mind, they can't afford anything more expensive.
Click to expand...
I chose a wrong example Helmut. I'm fortunate to be in
a branch of electronics (avionics ATE), where being well
within spec and bullet proof is far more important than
the cost of an ic. So an LT part that models properly
in LTspice (even at N times the price) is ok.

[snip]

PS: I am not an employee of LT if that matters.
Click to expand...
I know. Thank you for your remarks.

--
Tony Williams.
 
you're right Ib is actually 681nA but that's because the model reflects
the first revision, it's dependant of the Bf, my guess is that no one
created a second version of this model.
 
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