EM compatibility considerations for switching power supplies

8th October 2013

CUI Inc

Nat Bowers

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Whitepaper

Switching power supplies generate Electromagnetic Interference by virtue of their inherent design characteristics. Internal switching power supply circuits that generate undesirable emissions that are rich in harmonics can cause electrical interference both internally to the circuit in which the power supply is installed and to other electronic equipment in the vicinity of the emission source.

Introduction

This application note examines the rules and regulations governing control of EMI, discusses types of noise generated by switching power supplies, and provides basic guidance for EMI mitigation, whether the power supply is installed in other equipment as part of a larger system or designed for stand-alone applications.

Laws, regulation and international cooperation

The electromagnetic spectrum has been widely used for broadcasting, telecom and data communications through intentional emissions of electromagnetic fields. There have also been unintentional emissions from many electrical and electronic equipment, such as arc welding machines, household appliances and computer equipment. In order to protect the electromagnetic spectrum and to ensure compatibility of collocated electrical and electronic systems from trouble free operations, regulatory bodies both within the United States and throughout the world community have established standards to control conducted and radiated electromagnetic interference in electronic equipment. This discussion mainly focuses on unintentional electromagnetic compatibility in systems that utilize switching power supplies.

Read and downlaod the full CUI application note: "Electromagnetic Compatibility Considerations for Switching Power Supplies" below.