In order to simulate a schematic component using EDSpice Simulator, i ts symbol must be associated with one of the available EDSpice circuit elements or with the subcircuit from EDSpice Subcircuits Library. This application facilitates the association of symbols in the symbol library to the available EDSpice circuit elements or library subcircuits and defining the component parameters. Also EDSpice Simulation references may be added to parts or the already assigned ones may be changed using this module.

Create required component using the Library editor in EDWinXP
Here the assignment of a subcircuit to a regulator is illustrated.

Symbol name: REG
Part name: REG
Package: TO220/3

Evoking EDSpice Symbol Editor

This module may be invoked from Project Explorer in the following ways.

1.Right click Library and select EDSpice Symbol Editor from the list.
2.Select EDSpice Symbol Editor from the Task list or from the Task toolbar.

The next step is to assign a subcircuit for the component. Click on “Subcircuit”. A window as shown below will popup.
The model as well as subcircuit library structures support the family approach of grouping the models. There are two purposes to group them as family libraries.

1. The user may find the models/subcircuits easier.
2. It may happen that model parameters/subcircuits have the same identifier.

For example BC807 from two manufacturers, Motorola and NS. In such cases they may be stored with the same identifier in different family library file and still be unique. This family approach of grouping the models and subcircuits are implemented using family prefixes.

Family prefix, if added to the Simulation Reference, makes the search by EDSpice (with the context as Simulation Reference), faster. In the case of models, the family prefix is the model parameters library file name without the extension. The Family Prefix in the case of subcircuits is the subdirectory under EDS_SBK where the subcircuit is stored.

For subcircuits:
Consider the subcircuit TL031_10 adopted from TI. Let this subcircuit be stored in the directory /EDS_SBK\TI_LIN. Here the search string is:-

@TL031_10 - without Family prefix
@TI_LIN.TL031_10 - with Family prefix

When the program searches for subcircuits then in the first case it would go through all subdirectories under EDS_SBK until the subcircuit is found or not. In case when prefix is specified (which is optional) then the search as above is proceeded by attempt to access subcircuit TL031_10 directly in /EDS_SBK\ TI_LIN. If subcircuit is found then OK, otherwise the search continues. Generally it works in similar manner as with model parameters.

Assigning a Subcircuit to the Symbol

The symbol can be assigned with a subcircuit by the following steps:

1. Select the appropriate library subcircuit from the list. To get the list of subcircuits in the library press. If the check box “Add family prefix” is checked, the prefix gets added to the symbol. By checking the list may be filtered by displaying only the subcircuit with the exact number of pin the symbol has
2. Assign element nodes to the appropriate entries of the symbol.

When a subcircuit has been selected, the list of nodes, as expected by EDSpice is displayed. The sequence of operations is as follows:

- position the cursor on the entry and click the mouse. The operation is confirmed if the selected entry is marked by a rectangle.
- select the appropriate node for this entry from the nodes list. The operation is confirmed if the entry is marked with the number of the node selected from the list.

The same operation must be repeated for all entries in the symbol.
Thus the symbol will be assigned with the subcircuit.

Save the symbol using “Save”.
Select YES.
The symbol REG is saved in the “A.Symbol” library.

Click on “Update” so that the part get updated. The part REG is saved in the A.PART.

Select Editor ->Parts. Thus the Part library gets loaded to the EDSpice Symbol Editor out of which the required part is selected.

Search the Part in the Part library.

Save the Part by clicking on the “Save Part”.

Recreate the Subcircuit index for the updated component to get attached with the parameter.
File -> “Recreate Subcircuit”

From the Library Editor -> Simulation Parameters -> EDSpice Simulation Model/ Subckt indicates the subcircuit attached to the symbol and EDSpice Simulation Ref refers to the attached subcircuit to the Part.