How to add a model to LTspice (SwitcherCad)

This assumes you want to add a new model for a new device similar to one in the existing library. Here are three different methods.

Method 1: Modify Libraries

This method makes sense if you are working on your own computer, where you can update your own libraries and use them again.
  1. Look under C:\Program Files\LTC\LTspiceIV
    (or C:\Program Files\LTC\SwCADIII )
  2. Go to the directory lib\cmp
  3. Look at the list of standard devices to figure out which kind you want, such as: Each line in each of these files has a model for one device.
  4. Add a line with the .model line for your device to the end of the appropriate file using a text editor.
    Note you may have to adapt the model line to match the pattern in the file. It should be pretty easy to figure out.
Now when you open LTSpice, you should be able to pick the device you've added as though it was one of the existing models.

Method 2: Using an external library file

This will work well if you are using a computer where you can't edit the built-in library files, or where edits will not be saved, but where you may have several models in one file which you would like to be able to use in the future.
  1. Save the file which contains the model you want to use in a directory where you have write access. (For example, I use c:\windows\temp.)
  2. Insert a SPICE directive from the edit menu,
    directive menu item
    by using the directive menu button icon, or by typing 'S'.
    In the text box, type
    .lib path to your library file
    so, for example
    .lib c:\windows\temp\myfile.sp3
  3. Change the name of the component in your schematic to match the exact name of the model in the library file.
Now when you simulate, your new device model should be used.
Note: you can use the .include directive instead of the .lib directive if you wish.

Method 3: Inserting the model directly into the drawing

This will work well if you are using a computer where you can't edit the built-in library files, or where edits will not be saved, and that there is only a single model you want to use.
  1. Open file which contains the model you want to use, and copy the model into the clipboard.
  2. Insert a SPICE directive from the edit menu, by using the icon, or by typing 'S'.
    In the text box, paste the model from the clipboard.
  3. Change the name of the component in your schematic to match the exact name of the model in the model line.
Now when you simulate, your new device model should be used.
Note: Because you now have the model saved as part of your schematic, this is completely portable between computers.