Design Of Led Driver With PWM Dimming Function

Recently, with the increasingly serious energy crisis, by virtues of itshigh luminous efficiency and long life the LED light source will becomeone of the best choice to replace the traditional lighting. Due to the lowefficiency and the large fluctuations in output current, the LED driver’slife span can not match with the life span of the LED light source. Theseshortcomings have seriously hampered the promotion of LED lighting.Thus, the development of a high-efficiency, high power factor, long lifeLED driver is of great significance.First of all, the paper detailed the background and significance of thedevelopment of LED lighting. Then the article analyzed the basiccharacteristics of the LED light source. At the same time, conductedin-depth theoretical analysis about the DC/DC conversion technology,power factor correction technology, electromagnetic interference,transformer design and LED dimming technology. Based on thesetheories, a T8fluorescent tube driver is manufactured on the basis ofLNK419control chip. The driver achieved high power factor andconstant output current by the single stage flyback converter. On the otherhand, the flyback converter played an important role on the input tooutput isolation. The PWM dimming function is added to the driver toenhance the effect of energy saving and environmental protection. Finally,a reasonable and effective solution is put forward in order to solve theelectromagnetic interference problems.I successfully developed a single stage constant current LED driverwith PWM dimming function. The input voltage of the driver isbetween185VAC and265VAC. The output voltage is50V and outputcurrent is0.50A. At last, we conducted a series of experiments based onthe prototype.The test results confirmed that: the LED driver had highefficiency, simple structure, low cost, and had a strong practical value.