Problems with SPICE models from vendors

What I found disturbing was that the bias currents were way in excess of MAX specification.

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Thanks! Using LTspice solved the problem. It also ensures that the model accurately mirrors the schematic. With the DOS TopSpice, transcription errors can cause problems (and did!). However, it *would* be of great use if:

1) one could easily edit wires (length, placement, number of corners and where corners are). 2) one could have a little window by a (chosen) node that gave the DC (or other value). 3) that the output, both text and graph could be directly saved. .PRINT and .SAVE just do not cut it here. 4) that the duplicate function would allow creation of more than one; sometimes you need 5 more of something... ************* I noticed that in some cases, setting ITL1 and/or ITL6 "small" can allow something to converge, where a setting of 200 or more can kill convergence. And he higher the value of ITL1 and/or ITL6, the worse the problem is. Why??

[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.

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Tony Williams.

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

Kevin Aylward snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

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."

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Tony Williams.

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.

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 snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

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

That is not within the confines of SPICE in general, so talk to NASA...

...don't snile when you can smarl?

In article , Kevin Aylward wrote: [snip]

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.

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Tony Williams.

Oh?

It may well be, but its a return on investment. *How* beneficial would it be to LT?

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 snipped-for-privacy@anasoft.co.uk

SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.

"Tony Williams" schrieb im Newsbeitrag news: snipped-for-privacy@ledelec.demon.co.uk...

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.

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.

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]

I know. Thank you for your remarks.

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Tony Williams.

In article , Kevin Aylward wrote: huge snip]

You can of course conveniently ignore any of the other posts I have made praising/recommending LTspice.

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Tony Williams.

Sure. That would be a good feature.

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

And it is not difficult to do, it just takes time. 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.

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.