LTSpice Supply for Bipolar Op-Amps

[jpanhalt]

I was playing with LTSpice and op-amps that needed a bipolar supply. I did it in a way that was obvious to me. Then, I checked Linear Technology's models. This is what it does:

That is just not intuitive to me. Anyone else have a problem with it? (I am not arguing. It is easier to do.)

Anyone have a model for a TLE2082, which is an imporved TL082 . A quick Google search didn't find it. The main difference that I see is the GBW. Attached is the model for TL082.

John

 

[ronsimpson]

That is just not intuitive to me.

John,
Having a positive that is -15V is hard on the head.
It is like having a not-disable pin. (/disable) How about an enable pin.
NOT NAND gate.

 

[jpanhalt]

Yes, it seemed like something should be flipped. I have a feeling that the fainter symbol characters don't affect the simulation, which probably only looks at the bold values. You can do a similar thing in Eagle. It really doesn't care what you draw inside the symbol walls.

BTW, do you know which parameter/value in the TL082 model would correspond to the unity GBW, if that is even included as such? The symbols and values meant nothing to me. The GBW for the TL082 is 3 MHz and for the TL2082 it is 10 MHz. Slew rate is 13 v/us and 45 v/us , respectively. The simulation is for an LF amplifier, and I am most interested in simulating quantitatively the effect of the GBW.

John

 

[eTech]

Hi

I think if you look at enough models its done different ways.
I connect a split supply this way. You can use the same parameter to set different voltage levels

 

[eTech]

Here is spice model (Its on the TI site).

 

[jpanhalt]

Thanks for the model. I looked and did not see it. I am sure that won't be the last time I miss something obvious.

Your way of handling the bipolar supply is similar to what I did at first. That is, I followed the intuitive meaning of the supply symbols. Then, when nosing around for the correct spice model, I looked at a Linear Tech "subcircuit definition" . That is where I found the image posted originally. Both "designs" worked. I was just wondering whether there was some explanation for the Linear Tech symbol other than my assumption (post#3) that it's the directives, not the symbol that matters.

John

 

[alec_t]

I usually do my dual supplies the same way as etech.
That symbol is initially confusing when used as per post #1 and also when designating an AC source!
The 'signal' symbol in the 'misc' folder makes you think, too!

 

[ronsimpson]

This is like installing one of the batteries backwards in the battery holder.
--------------------
Some very old cars had a 6V battery and a positive ground. (+ ground) NO the car runs on -6V.