To download the examples for Module 4, click Module_4_Examples.zip
What You Will Learn
- In SIMetrix/SIMPLIS, a "Device" is the combination of a symbol and an ASCII text
model in a deliverable form. The model may be plain text or encrypted depending on
the sensitivity of the intellectual property in the model.
- Models are categorized by type and associated with an appropriate symbol.
- How to view, edit, and delete model-to-symbol associations.
- Create a new schematic using the
- From the schematic menu, select
Result: The Select Device dialog opens.
- In the upper right hand corner is the category box, select NMOS. You can
press N twice to select this category.
- Select the 2N7000 as shown below.
- Click the Place button..
Result: The Model
Extraction dialog opens and you would normally enter the actual circuit operating
conditions in this dialog.
- Click Extract and place the symbol anywhere on the schematic.
You have just placed a nmos_sub symbol based on a 2N7000
model name. In order to do this, there must be a model-to-symbol association
which tells SIMetrix/SIMPLIS that the 2N700 uses a specific symbol. In the above
example, the 2N7000 is a built-in model, which has a built-in symbol and an association
between the model and symbol. For user defined models which you would like to place from
the Model Library, you need to associate models with symbols.
Associating Models With Symbols
There are two common ways to associate models with symbols:
- Use the Associate Models and Symbols Dialog
- Embed the association information in the model library file.
Exercise #1: View Model-Symbol Association
In this exercise, you will view the model-to-symbol association information for the
- From the menu bar, select
Result: The Associate Models and
Symbols dialog opens:
- In the Select Devices drop-down box, select the NMOS category as shown
Result: The available devices list is
populated with all NMOS.
- Select the 2N7000 from the list of available models:
Result: The association information for the 2N7000 model is
displayed on the dialog along with a symbol preview.
The Associate Models and Symbols dialog allows you to change or create
new categories, change symbols, and change the pin order. The Help button
on the lower right hand corner of the dialog links to a comprehensive
Undo Model-to-Symbol Associations
At times, models are accidentally associated with the wrong symbols. Although no
built-in GUI is available for removing associations within SIMetrix/SIMPLIS, you can do
this manually with a text editor. The user-defined model-to-symbol associations are
stored in a text file named user_v2.cat in the Application Data directory. This
is usually located in at the following windows symbolic directory: %APPDATA%\SIMetrix
To edit the user_v2.cat file, follow these steps:
- Open a Windows Explorer window.
- In the address bar at the top of the window, copy and paste the following text:
- Drag the user_v2.cat file into SIMetrix/SIMPLIS.
Result: The file opens in the text
This file stores each model-to-symbol association on a new line. To
remove any association, simply delete the entire line.
Embedding the Model-to-Symbol Association in the Model File
SIMetrix/SIMPLIS has the ability to embed the symbol information used for the model
inside the model file. A special comment keyword, *#ASSOC is used to define the
symbol, model library category, and pin mapping if required. For example the following
embedded association tells SIMetrix/SIMPLIS to use a 3 terminal NMOS MOSFET symbol for
*#ASSOC Category=NMOS Symbol=nmos_sub
In this case, the category has no spaces, and the Category name is not required to have
double quotes. For a Category name with double quotes, such as PSU Controllers, the
association line would be:
*#ASSOC Category="PSU Controllers" Symbol=MAX15062
Notice that this is the actual association information for the PSU Controller
Important: The *#ASSOC line must be placed right after the
.SUBCKT line which starts the model definition.
and Key Points to Remember
- In SIMetrix/SIMPLIS, a Device is the combination of a symbol and an ASCII
- Models are categorized by type and associated with an appropriate
symbol using the Associate Models and Symbols dialog.
- You can embed the symbol name and model library category in the
ASCII model library text file using the *#ASSOC