When designing and building electrical systems with high voltage, two important concepts to consider are creepage and clearance. Creepage distance refers to the shortest path that an electric current can take along the surface of an insulating material, such as a printed circuit board (PCB) or a plastic enclosure. Clearance distance refers to the shortest distance between two conductive parts, such as wires, terminals, or components, through the air. Figure 7-11 illustrates creepage and clearance for a typical integrated circuit (IC).

Several standards exist with creepage and clearance guidance, but how the standards pertain to operational amplifiers and other integrated circuits is largely left to interpretation and internal requirements. The guidance distances are significantly affected by pollution degree, maximum voltage, and the underlying application. In the case of creepage, the comparative tracking index (CTI) rating of the insulating material is a major factor. Different design techniques exist to improve creepage and clearance if deemed necessary, including adding PBC grooves, conformal coating, and, or derating the operating voltage.

Texas Instruments offers modern packaging with small dimensions that are designed to minimize PCB area. However, the requirement to meet any creepage or clearance specifications depends on the designer’s interpretation and implementation of any relevant IEC or system-level standards. For more information on this topic, visit the Demystifying Clearance and Creepage Distance for High-Voltage End Equipment document.