Training Insights: Ascent: Schematic Design Variants in Allegro X System Capture

Most electronic products have variations, such as a different RAM size or different supply voltages, because of various geographic locations. Variants, which are modifications of the base design, offer a powerful way to create and manage these variations in a design. A design variant is a schematic markup used to document the assembly variations on a PCB design and is also known as “stuffing options”.

Allegro X System Capture supports the creation and management of design variants on schematic sheets. You can create multiple variants and modify or delete the components in the base schematic for use in the variants. 

Creating a Schematic Variant

To create, edit, and manage a design variant in System Capture, do the following:

1. Select the Variants – Create Variants menu in System Capture.
2. Enter a name for the variant in the Create Variant window.

           
After the variant is created, System Capture switches to the Variant view to enable the editing of the variant data. The application window title indicates that the variant view is being displayed.

In the variant view:

• All editing features become unavailable to prevent inadvertent connectivity changes.
• All the toolbar icons are hidden except Design Explorer and the Property toolbars.
• The Edit Properties dialog box is replaced with the Variant Info form, which displays variant information for the selected object.

You can define components in the variants as Add Preferred Parts, Reset to Base, or Do Not Install (DNI). Let’s discuss them in detail: 

Add Preferred Parts

In System Capture, you can define alternate components to add or replace preferred parts. When replacing a part, the search criteria for compatible footprints are automatically applied, and relevant results are displayed. 

Reset to Base

Using the Reset to Base command, you can undo the changes made in the variant design and return to the base design. This helps designers easily reset the changes.

Do Not Install

You can also use the Do Not Install command to prevent parts from being mounted in assembly variants. This command helps identify installed and uninstalled parts easily. The DNI property icon lets you exclude the selected part from the variant.

Designing a Variant BOM

A Bill of Material(BOM) report lists all the components used in a design with the part numbers and values of the different properties of each component. You can also generate a design variant BOM in System Capture. A design variant BOM is a report that helps you place an order for required components.

You can check out another blog post on Managing Design Variations in Allegro X System Capture.

To learn more about this topic, enroll in the  Allegro X System Capture Basics course on the Cadence Support portal.

Click the training byte link now or visit Cadence Support and search for training bytes under Video Library.

If you find the post useful and want to delve deeper into the training details, enroll in the following online training course for lab instructions and a downloadable design: Allegro X System Capture Basics(Online).                                                    
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