User`s guide

5
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18 Creatin
g
Symbols for Models
Definin
g
S
y
mbol
Attributes Needed for
Simulation
If you created your symbols using any of the methods discussed
in this chapter, then your symbol will have these attributes
already defined for it:
• MODEL and TEMPLATE for simulation, and
• PART and REFDES for identification.
You can also add other simulation-specific attributes:
SIMULATION ONLY, and for digital parts, IO_LEVEL,
MNTYMXDLY, and IPIN(xxx).
Example: If you create a symbol that has electrical behavior
described by the subcircuit definition that starts with:
.SUBCKT 7400 A B Y
+ optional: DPWR=$G_DPWR DGND=$G_DGND
+ params: MNTYMXDLY=0 IO_LEVEL=0
then the appropriate symbol attributes are:
MODEL = 7400
ipin(PWR) = $G_DPWR
ipin(GND) = $G_DGND
MNTYMXDLY = 0
IO_LEVEL = 0
TEMPLATE = X^@REFDES %A %B %Y %PWR %GND
@MODEL PARAMS:IO_LEVEL=@IO_LEVEL
MNTYMXDLY=@MNTYMXDLY
Note
For clarity, the TEMPLATE attribute value is
shown here in multiple lines; in a symbol definition,
it is specified in one line (no line breaks).
Here are the thin
g
s to check
when editin
g
symbol attributes:
✔ Does the value of the
MODEL attribute match the
PSpice A/D .MODEL or
.SUBCKT name?
✔ Does the TEMPLATE
specify the correct number
of pins/nodes?
✔ Are the pins/nodes in the
TEMPLATE specified in the
proper order?
✔ Do the pin/node names in
the TEMPLATE match the
pin names on the symbol?
To edit an attribute needed for
simulation:
1
In the symbol editor, from the
Part menu, select Attributes.
2
Click the attribute in the list
that you want to chan
g
e (for
example, MODEL), or type an
attribute name into the Name
text box (for example
SIMULATION ONLY).
3
If needed, type a value into
the Value text box.
4
Click Save Attr.
5
Click OK.