中文摘要：

LED照明是提高照明质量、节约能源的重要举措。可靠高效的LED恒流驱动电源设计是充分发挥LED照明优势的关键所在。开关电源被誉为高效节能型电源，它非常适合做LED恒流驱动电源，现已成为LED驱动的主要电源。文中设计了一款基于TNY268的反激式小功率开关电源，该电路结构简单，输出电压和恒流驱动值均可随意设定；并依据设计制作了样机，对样机进行了参数测试。实验结果证明：输出电压对输入电压的变化适应力强，输出精度和效率较高。

英文摘要：

Switching power supply is known as high efficiency and energy saving power supply. It represents the development direction of regulated power supply, and becomes the main productions of regulated power supply now. The switching power supply with low power is designed based on TNY268 in this paper, which works on fly - back mode. This circuit structure is simple, we can arbitrarily set the output voltage and output constant current. We make a prototype based on the design, and test the prototype. The experimental results indicate ： the output voltage is adaptable to the change of the input AC voltage, and output precision and efficiency are high. The design is successful very much.