如何能在享受光明的同時又能兼具節能省電的方法，那就是現在大家耳熟能詳的LED，它不僅體積小且為全固體發光體，耐震、耐衝擊不易破碎，廢棄物可回收。近年來出於晶片技術的改良，製造成本正在急劇下降，近三年來LED的價格下降了近50%，正朝著高效率與低成本的方向發展。本文運用了返馳式電力轉換器和數位訊號控制器作為電壓迴路提供充足與穩定的頻寬，設計一個Flyback電路，運用電力轉換器來控制PWM和操作在不連續模式(DCM)下，去驅動18W LED燈。透過實驗結果可觀察出LED電路的特性與輸出入關係。 We can both enjoy the lighting and energy-saving by use of LED lamps. The LED is a small size solid lighting source. It is anti-vibrating, impact resisting and recyclable. Because the semiconductor manufacturing technology is improved, the cost is reduced 50% in recent 3 years. The efficiency and cost are both reinforced rapidly. In this thesis, the flyback converter and digital controller are both studied. The voltages and currents of the flyback converter are well controlled. The drive condition of the flyback converter is set at discontinuous mode (DCM). The rated power of the LED lamp is 18W. From experimental results, the input-output relations of voltages and currents are well designed and the conditions are satisfied.