瞬态抑制技术 Transient Suppression Techniques for TOPSwitch Power Supplies Application Note AN-20 Introduction AC power mains occasionally have transient surge voltages. Lightning strikes and AC mains load switching are just two examples of many possible conditions causing transient voltages. Consequently, all off-line power supplies must provide some level of protection to suppress the effects of such transient voltages. This application note presents design techniques which improve TOPSwitch power supply operation through most AC mains transient surge voltages. Properly designed transformers, PC boards, and EMI filters not only suppress the effects from transient voltages but also reduce both conducted and radiated EMI emissions as well. These techniques can also be used in applications with DC inp……