The Off-line LED Driver IC With PFC

With the great development of semiconductor technology, the advantage of LEDsusing in the lighting application is remarkable, such as energy saving, environmentprotection, durable. However, there are some problems that restrict the furtherpopularization of LED lighting. Driver is one of the most important problems, not onlyis the price too high, but also the quality needs to be improved.Based on the above problems, in this thesis, a LED driver which is suitable forlighting application is designed. It is a AC power supply management chip, so it is moreconvenient；There is a Power-Factor-Correction block in the chip to reduce the powerconsumption; furthermore, it is more cheap and simple for the Primary-Side Control. Inthe normal operation situation, the output current is500mA, the fluctuation of theoutput is less than2percent; the power factor is95%.In the process of the chip design, we analyze the overall architecture of the chipand the working mode, as well as the feedback method first of all. Then, the overallspecifications are set, such as the output current and the power factor. On this basis, themain blocks should be contained is determined. The band-gap reference is the source ofthe reference voltage and the bias current. The LDO provides power for all blocks in thechip. The multiplier is the core to realize the PFC and constant current. The UVLO isthe one of the protection blocks to avoid damage. In this thesis, the band-gap reference,the LDO and the multiplier are discussed particularly. In the design course, both thetraditional circuit structure and our circuit structure are introduced. Besides, thesimulation results are presented.In the end, the part of power supply made up of the blocks mentioned above isanalyzed and simulated. It is discussed particularly for its great importance.