Switch-Mode Power Supply (SMPS) Emissions Filtering: Attenuation vs. Leakage Trade-Off

The AC/DC power converter is often the sole interface between a piece of equipment and a building’s electrical installation, which is in turn connected to any number of other off-line systems. It is also the element separating the hazardous high voltage mains from user-facing safety extra low voltage (SELV) networks. Accordingly, AC/DC power converters fall under a great deal of regulatory scrutiny, with mandates ranging from energy efficiency to safety to electromagnetic immunity and emissions. The requirements of each regulatory authority can often spawn contradictions in the resulting engineered solutions.