Switching power supplies generate EMI because of the inherent design. Domestic and international regulatory bodies regulate these emissions through promulgation of rules and standards such as the FCC Part 15 rules and the CISPR 22 standard. An understanding of EMI fundamentals and best practices to mitigate the different types of EMI when implementing a power supply is crucial in design. However, it is also important to understand that a power supply is just one part of an electronic system with multiple EMI sources, so evaluating the power supply’s EMI performance within a system is vitally important.