| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 100 === LED possesses the characteristics of energy saving and high efficiency. In the near future when energy shortage will come as no surprise, LED lighting will become the mainstream product in the lighting market. This paper presents low-cost and easy-to-maintain flyback converter as the LED driver. The author adopts constant-current and constant- voltage combo IC controller as the feedback control circuit, which feedbacks output to PWM IC to control switch and which is able to maintain a stable DC output voltage even under the condition of a wide range of AC input. The function of constant current provides overload protection to avoid the LED getting burned. In the safety design, the author uses transformer and opto isolator to meet the requirement of electrical isolation. On the basis of the operation principles of flyback converter, this thesis proposes a LED driver circuit, whose AC voltage input works in the range of 85V to 265V and whose DC output power supply is 24V/0.4A. In the final phase, this circuit is assembled into household LED lamps to verify the design theory and its practicality.
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