Input Filter Design for Switching Power Supplies开关电源输入滤波器的设计

The design of a switching power supply has always been considered a kind of magicand art, for all the engineers that design one for the first time.Fortunately, today the market offers different tools that help the designers. NationalSemiconductor was the first company to offer the “Simple Switcher” software, and anon-line simulation tool that allows the design and simulation of a switching powersupply. New ultra-fast MOSFETs and synchronous high switching frequency PWMcontrollers allow the realization of high efficient and smaller switching power supply.
All these advantages can be lost if the input filter is not properly designed. Anoversized input filter can unnecessarily add cost, volume and compromise the finalperformance of the system