model parameters in LT Spice

I've just started using the free version of LT Spice and haven't had a problem doing simulations as long as the components are in the library. Now I need to do a simulation using a component that's not in the LT Spice library, the 1N4001 diode. Somebody sent me the model for the 1N4001, which is great. So my question is, after you put a diode symbol in the schematic, how do you assign parameters to it? Here is the text I received for the

1N4001: *SRC=1N4001;DI_1N4001;Diodes;Si; 50.0V 1.00A 3.00us Diodes, Inc. diode

.MODEL DI_1N4001 D ( IS=76.9p RS=42.0m BV=50.0 IBV=5.00u

  • CJO=39.8p M=0.333 N=1.45 TT=4.32u )

Based on the text for the diode models in LTSpice, I guess I need a string of text that looks something like:

.model 1N4001 D( IS=76.9p RS=42.0m BV=50.0 IBV=5.00u

  • CJO=39.8p M=0.333 N=1.45 TT=4.32u )

First, obviously I put a diode symbol in the schematic; then what?

Reply to
Michael Robinson
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Select the "edit" menu, scroll down to "SPICE directive", click on it, and paste your text into the box that will come up. Once you have pasted in the text you want, click on OK and position the block of (black) text, on your circuit diagram. I once screwed up by pasting the text in as comment rather than as a SPICE directive and failed to notice that the relevant block of text in my circuit diagram was in blue, not black.

-- Bill Sloman, Nijmegen

Reply to
Bill Sloman

He'll also have to make sure the schematic symbol and the .model line have the same name. Like the diode should be D1 1N4001 and the directive should be .model 1N4001 D(....

John

Reply to
John Larkin

Add the 1N4001 model to the end of the standard.dio file in your lib/cmp directory. It will then appear as one of the diode options from the standard symbol.

You need to restart LTSpice for the change to take effect.

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"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
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Reply to
Fred Abse

Careful. Next time you update the software it might be gone :-)

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Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

Yup. Learned that a long time ago. Personalized components go into a separate libraries, mylib.lib (models) and mylib.slb (symbols), so updates don't overwrite add-ins. ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Now

which

schematic,

What, no personalized files? thompsontrannys.lib or something?

I always keep looking in jscsupply.lib, for chocolates, but can never find any ...

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

Now

which

schematic,

Sure! That's what mylib.lib is...

98 .SUBCKT entries

142 .MODEL entries

And then there's mylib.slb, symbols, with 667 entries... I've created many symbols to ease importing subcircuits created by others, portions of chips designed by the customer, posts here, datasheet subcircuits, etc.

Examples are given on the "Subcircuits & Symbols" and "S.E.D/Schematics" pages of my website.

It's nearing Halloween... my wife has to keep buying and buying and buying... :-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

We always keep a stash on hand for Halloween. But it's hit or miss. One year lots of kids come, other years none. Because we are located at a cul-de-sac, long driveway and all uphill. Then I'll have to eat some and we bring a big bag to church.

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

My experience with this, and yes I've done it with the BJT file, is that the update protects additions. So that's a good thing. Might change at any time, though. Or maybe is already changed? Risky.

Jon

Reply to
Jon Kirwan

Pretty much the same here. End of cul-de-sac, uphill, no youngsters on the block. Used to be bus-loads of Hispanics, but none in recent years. ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Being diabetic, I don't buy any candy.

I've lived here 11 years and never had one 'Trick or treater' so apparently the stores I spread about the dangerous, crazy old man at the end of the street is still working! ;-)

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.
Reply to
Michael A. Terrell

Yup. That's like not backing up anything and then one sunny day ... poof ... gone.

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Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

Thanks for the answers, all.

Reply to
Michael Robinson

From the manual:

"Component databases are merged in the update process so if you've added devices to your installation, those additions won't be lost when you run the automatic update utility."

I'd still keep backups, though.

I don't update very often (IIABDFI). Running apps under wine, I'm leery of changes.

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"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
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Reply to
Fred Abse

Maybe they're all wearing Joe's pink underwear?

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"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
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Reply to
Fred Abse

Now

which

schematic,

I found that the update function never worked here. So when I update it's a clean slate re-install and that wipes just about everything. Even if it didn't I wold not take that risk. Losing a large number of SPICE models can throw an engineer a real curve.

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

I had a neighbor once who said that he'd just put a bowl out there with a sign: "One candy per kid!"

I asked, "How do you be sure some kid doesn't take them all?"

He said, "Oh, you don't put any candy in it - just the bowl and the sign." (the premise being that they'll all assume the previous kids got it all.) ;-)

Cheers! Rich

Reply to
Rich Grise

It's worth keeping file with all your additions to each of the standard ones, because otherwise the next update will wipe you out.

Also I've recently learned the hard way that it's even more helpful to include all the models explicitly, and keep the ones you're using in the same directory as the simulation--one directory per project, or maybe more.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs
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Reply to
Phil Hobbs

I have at least 90 different device libraries... each provided by a foundry.

MANY have NMOS/PMOS as device names or other such replications.

So I don't automatically load anything but garden variety components, generic resistors, capacitor, etc... and my PSpice gimmicks-for-ease-of-measuring tool sets.

Each test schematic has one or more .LIB calls to libraries needed for that particular project only. This approach also makes it easier to swap between typical and worst-case versions of libraries.

I certainly believe in one directory per project... at the top level, then sub-directories for each cell (chip design).

But I don't keep my device libraries there. After all the .LIB statement _can_ contain path information :-)

If there's a fear of a huge library... not-to-worry. PSpice provides a compression technique that contains only the components used... to pass a schematic along to an associate. ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

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