Preferred component reference designators while drawing CAD

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Preferred component reference designators while drawing CAD

Anytime you place a component in a schematics or PCB layout, the component gets assigned a reference designator (sometimes shortened to “refdes”). This alphanumeric code is shorthand for a specific component and it helps the design team properly communicate specific components between team members, inside design documents, and within printed circuit design software.

Reference designators are not just random sets of letters and numbers, they follow a specific system that designers use to call out specific components in a PCB. With the right design software, you can place and edit reference designations throughout your design documents, including in the PCB layout, component data, and schematics. Your PCB design software also helps you stay synchronized as you place and modify your PCB reference designators.

PCB design software with advanced CAD tools for creating components and placing your PCB reference designators.

Every component you place in your schematics, circuit board layout, bill of materials, and many other design documents will have a corresponding reference designator. The reference designator that appears on the PCB will be assigned to a specific component in your design documentation by your ECAD software, or the user can customize the reference designation to have a specific format that is necessary for the current project.

Using the best PCB layout software with an integrated schematic editor makes it easy to keep reference designation synchronized between schematic sheets and the PCB layout. As you work through your printed circuit project documents, there is the possibility for your schematics, PCB layout, bill of materials, and final manufacturing outputs to become desynchronized.

All PCB reference designators appear on the surface layers of a PCB on the silkscreen layers (top and bottom overlay). The reference designator for a component is a letter and number combination assigned to a specific component. Each component gets its own reference designator, meaning reference designators are never repeated. The reference designator for a specific component can be seen in your schematic design documents, PCB layout, and bill of materials as you create the database for your design.

Common PCB Reference Designators:

The list below shows a few of the common PCB reference designator prefixes used in circuit board design software:


RFixed resistor
RNResistor network
RVVariable resistor
CCapacitor (network, fixed or variable)
QTransistor, FET, SCR, TRIAC
DDiode, rectifier, Zener, varicap, LED
DLMultisegment display (any type)
VR, QIC voltage regulator
UIC integrated circuit
JSocket, jack (female)
PPlug (male)
JPJumper (pins, trace, or wire)
Y, XCrystal
MModular subassembly, daughter board
SMechanical switch
B, BTBattery