referensdesignator

Referensdesignator, ofta called reference designator in English, is a unique identifier assigned to each component or circuit element within a schematic or printed circuit board (PCB) layout. The designator consists of a prefix that indicates the component type, followed by a number that identifies the instance. For example, R1 designates the first resistor, C4 the fourth capacitor, U3 an integrated circuit, and Q2 a transistor. Some components comprise multiple parts, which is reflected in designators like U1A and U1B for different portions of the same package.

Designators are typically assigned during schematic capture or layout planning and must be unique within a project. They serve as references in documentation, bill of materials (BOM), assembly drawings, and service manuals. The designator is distinct from the component’s electrical value (such as resistance or capacitance) and from the footprint or part number. This separation allows engineers to change a component’s characteristics without changing its reference in documentation.

Common prefixes used in practice include R for resistors, C for capacitors, L for inductors, D for diodes, Q for transistors, U for integrated circuits, F for fuses, J or P for connectors, TP for test points, and SW for switches. Some conventions also use X or Y for crystals or oscillators.

Standards and conventions around referensdesignator vary by region and organization. Guidelines from bodies such as IEC standards and ANSI/IEEE provide overall structure for circuit diagrams, while individual companies may define internal naming rules to ensure consistency across projects.

In use, the referensdesignator helps locate components on a board, maps to the BOM, and links engineering data to manufacturing and service workflows, making it a fundamental element of circuit documentation.