| LED lighting is a new way of lighting emerging in recent years.The traditional lighting market position is replaced by LED lighting gradually because of a series of advantages,such as low carbon,environmental protection and high efficiency and so on.With the popularity of LED lighting,on one hand people have more stringent requirements in price,and on the other hand have higher requirements on their safety and diversity.Therefore,a study on low-cost and high-security LED driver has become a very hot topic in recent years.Based on the studies of various kinds of technologies and the working principle of L ED driver,one line-voltage-compensation circuit structure is proposed in this paper.And the structure is achieved on basis of phase detection method aiming at improving the deficiency of existing line-voltage-compensation circuit.The chip is designed based on 700 V high voltage BCD process.The liner adjustment rate is improved effectively by using this compensation circuit and a better compensation effect is realized without extra chip pins or other peripheral devices.The security and diversity of the chip are increased greatly with the over-temperature protection circuit and dimming circuit.Based on the set of indicators,the overall circuit design analysis,simulation verification,and the corresponding layout design are completed in this paper and the sample of the chip was tested.The test results show that the power of the lighting system is 5.86 W under 220V(AC),and the efficiency is 82%.The function of line voltage compensation circuit is normal by observing the waves and the waves indicate that the compensation effect is good.The linear adjustment rate is 1.6% from the test results.Further tests show that the stroboscopic depth is 15% and the default temperature of over temperature protection is 138℃ and the surge voltage can reach 1200 V with the help of voltage dependent resistor.The chip designed in this paper has met the requirements of design specifications and is superior to existing switching power supply drivers and linear constant current drivers in terms of price and performance. |
