How to simulate OPT in LTspice?

[Akita]

Anyone know how to simulate OPT in LTspice?

Let say 2500:8

[Ty_Bower]

Try using two inductors with a K directive. According to the help file, the inductance ratio should be the same as the transformer's impedance ratio.

[oshifis]

Could anybody explain me what is the compatibility between PSpice and LTSpice? Can the PSpice .lib (library), .slb (schematics symbol library), .olb (OrCAD capture library) and .sch (schematics) files be used in LTSpice?

[koolatron]

Since the engine is SPICE either way, you should be able to import the model files with some minimal work. If I remember correctly, LTSpice will let you build schematic symbols and associate its ports with a SPICE model. The code's the important part, as long as the guts are the same you should be able to make it work.

[kevinkr]

You can use most .lib files if their syntax is similar enough to ltspice's native format, however I have never had any success with importing symbols or schematics from other flavors of spice.

[Robert McLean]

Anyone know how to simulate OPT in LTspice?

Here's how I do it. I use the attached spreadsheet that I developed. Note that this is just something I whipped up for myself, I have not made it super user friendly, it assumes you know about excel, and copying and pasting etc.

It handles single ended, push pull, UL of either SE or PP type, and does multiple output taps if wanted. Its only a linear model, just gives the overall frequency you specify. It doesnt model core effects, ie saturation. A lot of the parameters such as winding resistances are just guesses on my part, put in better ones if you know them.

Brief instructions :
Go to the first worksheet ( "Main Data" ) and either select from a transformer already there, or enter specs for one of your own. For example for the 2500 to 8 ohm you asked about you may pick the HAM12627SE type. Copy and paste the data given for that into the first line of the appropriate worksheet, in this case the SE UL tab. Change the cells with tap values if you wish. The spreadssheet calculates the values, and shows two LTSpice models, one with output taps and one without. Copy and paste the one you want into your .lib file of transformers subcircuits or onto your spice schematic or however you prefer to get it into spice, and away you go.

[Akita]

Ty,

I get your idea. Thank.

Robert,

Great job! Thank for sharing the file.

[Dedessus Totof]

Hi Robert

Thanks a lot for your shared files
I use it for a short time now

But I've something to ask to you

Can you complete your spreadsheet with a CFB section

near like the UL tap in the Inductance, in fact, to simulate
far away my OPT

If it's possible and if you need real value about my OPT
Ask it , of course

I have on hand SE and PP with CFB and the way to do it is very similar
in front of UL

Best regards

[Michael Koster]

Originally Posted by Ty_Bower

..the inductance ratio should be the same as the transformer's impedance ratio.

Why?
The 2 coils are on the same core so both the impedance ratio and inductance ratio will be = turns_ratio^2 according to Faraday

Originally Posted by Robert McLean

Here's how I do it. I use the attached spreadsheet that I developed. Note that this is just something I whipped up for myself, I have not made it super user friendly, it assumes you know about excel, and copying and pasting etc.

Interesting!

It looks like you are taking the transformer frequency response spec, making some assumptions about the source and load resistance, and then deriving an estimate for inductance from those assumptions. I wonder how accurate this is going to be from manufacturer's FR specs if they don't also specify the source and load resistance conditions.

I'm not quite following the derivation of the coupling factor K. Is the leakage inductance buried in the computation somewhere? Guess I need to study it some more...

Cheers!

[revintage]

Ty_Bower is so right. Check post 1 and 2! The picture together says it all!
Winding ratio in relation to inductance or impedance is another thing that works with the formula above.