| Summary: | LED is a mature type of light source, which has many advantages compared with traditional incandescent and fluorescent: small size, low power consumption, long lifetime, high brightness, good dimming, fast response, reliable and durable , safety and environmental protection and so on. Now LED has been applied in many fields, such as traffic lights, car lights, LED backlight and indoor lighting. So the study of LED is both meaningful and necessary.
In this paper, there is a brief introduction about the history of the development of LED. Then the second chapter has an overview of LED, including advantages, disadvantages and applications of LED, light-emitting principle, the characteristic parameters (luminous flux, luminous intensity, brightness and color temperature), electrical properties and three connection modes of LED: Parallel, series and mixed. On the basis of a preliminary understanding of LED. Chapter 2 is also on the basis of the LED driver circuit. LED has both constant current and constant voltage control mode. Chapter 3 is about LED driver can be powered by AC or DC power. LED driver circuit is divided into the linear circuit, the switching circuit, feedback circuit and modulation circuit. Chapter 3 also to analyze the performance of the drive circuit. Taking into account the protection of the circuit, the intelligent control module, which includes short-circuit and overcurrent protection, open-circuit and overvoltage protection, undervoltage lockout protection. Then there are some considerations and supplementary to other factors of the drive circuit. In the previous theoretical basis, Chapter 3 introduces the practical LED driver design which use one core chip to design the circuit and PCB, some measurements result also include.
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