Research about primary side regulation flyback LED driver

HUANG Dengke, LIU Tuofu, WANG Zhengshi

(College of Electrical Engineering, Zhejiang University,Hangzhou 310027, China)

Abstract: Aiming at the small size and lowcost requirements of the LED driver, the primary side regulation(PSR) flyback LED driver was investigated . After the analysis of the principles of general flyback circuit,the relationship between output current and the primary current, auxiliary voltage was established. Then the working mechanism of PFC part, signal sampling part, and protection part of PSR circuit were discussed. A method was proposed to improve the efficiency by adjusting the inductance of the primary side ,and let the MOSFET to work at quasiresonant mode.The design steps of the key parameters were given to design a PSR prototype, then the PSR prototype of a SSR circuit was compared with the same specification. The research result shows that the PCB size is significantly reduced,the number of components is reduced by 1/3, efficiency is increased 2% , other electrical performance is similar. The results indicate that PSR circuit is of high practical value.

Key words: primary side regulation(PSR); flyback; LED; driver