Reference designators in electronics

Reference designators are labels used in electronics design to identify and differentiate components on a schematic or printed circuit board (PCB). Each component has a unique reference designator, usually a letter followed by a number (for example, R1 for resistor 1, C2 for capacitor 2). These designators are important for several reasons:

• Identification: They help avoid confusion and mistakes during assembly and troubleshooting.
• Documentation: They make it easier to create accurate lists of materials (BOMs) and assembly instructions.
• Communication: They help different teams, like design, manufacturing, and quality assurance, understand each other.
• Design Organization: They ensure all reference names are labeled in a logical and sequential way.
• Automation: Automated assembly machines use reference designators to place components accurately on the PCB.
• Troubleshooting: They help technicians quickly find and test specific components, speeding up the troubleshooting process.

Hierarchical designs

In hierarchical designs that use schematic modules, components inherit hierarchical designators from their module instance. For example, a resistor R1 in instance MOD1 appears as MOD1:R1 on the PCB.

You can simplify these hierarchical designators using the Flatten reference designator for module components feature. When enabled, hierarchical designators convert to sequential designators (for example, MOD1:R1 becomes R101, or another sequential value).

Managing designators

Fusion provides tools to manage reference designators:

• Renumber Designators: Automatically renumber components in a logical, spatially ordered sequence
• Flatten reference designator for module components: Convert hierarchical designators to simple sequential designators

Inspector fields

The Inspector displays designator information for selected components:

• Name: The component's reference designator
• Module: Shows which module a component belongs to (for hierarchical designs)
• Flat Designator: The simplified sequential designator (when flattening is enabled)
• Full Designator: The original hierarchical designator (when flattening is enabled)

In the schematic, the 2D PCB Instances field shows which PCB footprints correspond to a schematic part.