A constant current LED driver based on flyback structure with novel primary side control

摘要

A primary side control LED driver with a novel constant current control mechanism is proposed in this paper. In order to simplify the peripheral circuits, the proposed driver employs two cascaded power MOSFETs to eliminate auxiliary winding. The resonance occurs in the transformer will couple to the connection of power MOSFETs. Thus the system can obtain the demagnetization information by sampling the resonance. Based on this, the system can output constant current by adopting charging and discharging module. The control IC has been designed in CSMC's 0.8-??m 600V process. Simulation results show that the average output current precision is within +4.7% and the demagnetization time detection error is less than 0.2%.