Mitigating EMI in Switch-Mode Power Supplies (.PDF Download)

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Switch-mode power supplies (SMPS) are the dominant type of power supply in electronic equipment today. Their small size and high efficiency make them desirable in virtually every kind of portable and battery-operated device, as well as ac-main-powered equipment. However, their use comes with tradeoffs, namely electromagnetic interference (EMI).

When packaged together with an SMPS, sensitive circuitry can be overwhelmed with EMI and fail to operate properly. As a power-supply designer, you’re responsible for determining what effect EMI may have on the operation of your product as well as other equipment in the same environment. Then you must initiate a design that will minimize the EMI while maintaining high efficiency with the power supply. Here, we’ll discuss this challenging design problem and present a mix of solutions to help you achieve that goal.