Unknown Subcircuit After I downloaded a MOSFET. asy file in the directive from LTspice simulation

Thread Starter

Circleplus7

Joined Aug 10, 2020
21
Hi

I have a strange question. I downloaded a MOSFET LTspice model (.asy) from official website and saved it in the directive. However, It still shows "unknown subcircuit." If I use ideal NMOS4, the simulation works. Could someone help me with why it happens and how to deal with it?
I attached my simulation file and MOSFET .asy file.

Thank you

error.JPG
 

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Papabravo

Joined Feb 24, 2006
21,262
The problem is that your symbol does not reference a sub-circuit file. This sub-circuit specification might be in a library, or it might be in a standalone file. It is definitely missing from my system and yours.

You do not want to use the generic NMOS part in LTspice; it produces very squirrely results, and you DO NOT want to use the NMOS4 symbol - that is for chip designers and I'm pretty sure you have no clue how to use it.

I went to the onsemi site and it knows nothing about a spice model for the part. what official website did you actually go to??
 
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Thread Starter

Circleplus7

Joined Aug 10, 2020
21
The problem is that your symbol does not reference a sub-circuit file. This sub-circuit specification might be in a library, or it might be in a standalone file. It is definitely missing from my system and yours.

You do not want to use the generic NMOS part in LTspice; it produces very squirrely results, and you DO NOT want to use the NMOS4 symbol - that is for chip designers and I'm pretty sure you have no clue how to use it.

I went to the onsemi site and it knows nothing about a spice model for the part. what official website did you actually go to??
Hi

I downloaded MOSFET file from
https://www.onsemi.com/products/discrete-power-modules/mosfets/ntmts001n06cl#technical-documentation

This MOSFET spice model is .asy file, so I downloaded it and saved it in my directive. But I don't know why it is not working. In my previous experience, I can download the .lib file as MOSFET spice model, then I use .lib MOSFET .lib, it will work. But in this case, the MOSFET model is .asy file. How to make the symbol does reference a sub-circuit file ?

Thank you
 

Papabravo

Joined Feb 24, 2006
21,262
The ".asy" files are NOT models, they are graphical symbol outlines with pin definitions. T6_60V_LL_rev4p6_ltspice.txt is the name of the text file included in the .zip file. It is an encrypted subcircuit file with a plain text header. You can change the file extension from ".txt" to ".lib" and use an include statement on your schematic.
 

Thread Starter

Circleplus7

Joined Aug 10, 2020
21
I downloaded the actual library file from the website, renamed it with a .lib extension, cleaned up your schematic a bit and ran the following simulation:

View attachment 288141
View attachment 288142
All three files work fine when they are in the same folder. Good luck going forward.
Hi

I follow your suggestions, and it works! I am very much appreciated it.
Thank you so much.

Jiaqi
 
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