User Guide

Chapter 10 Preparing Your Design for Board Layout
280
Packaging the Parts in Your
Design
Symbols used in PSpice Schematics represent either an
individual gate of a packaged device, or a complete
device. When a symbol representing a single gate is
placed on a schematic, it is assigned a unique reference
designator (if Auto-Naming is enabled), and by default, is
made the first gate in the package. Packaging is the process
of collecting these individual gates into physical packages
and reassigning reference designators and gate names to
reflect how they are packaged.
The packager uses the package definitions for devices that
are in the package libraries. Package definitions contain
information such as the number of gates, gate names, and
pin number assignments. Package definitions are created
and maintained using the symbol editor. See Specifying
Part Packaging Information on page 6-201 for more
information.
The packager assigns reference designators, gates, and
package type attributes to parts on the schematic.
• The PKGREF attribute is the reference designator for
the package.
• The GATE attribute contains the gate identifier, if any.
• The PKGTYPE attribute contains the name of the
physical package (footprint) to be used (such as,
DIP14, LCC20).
• The REFDES attribute is the reference designator
normally displayed on the schematic. It is a
combination of the
PKGREF and GATE attributes.
• For example, if PKGREF=U31 and GATE=a, the
PKGREF will be U31a.
• The REFDES attribute cannot be edited directly.
• To change the REFDES, change either the PKGREF or
the
GATE attribute. The REFDES attribute will be
automatically updated to reflect the change.