A primary side controlled single-stage flyback LED driver with high PF

This paper presents a high power factor AC-DC LED driver circuit, which uses flyback topology and primary side feedback structure. The power factor correction circuit adopts the fixed on-time control mode and the structure design is simple. The system circuit operates in critical conduction mode (CRM), which reduces switching losses and is suitable for low power applications. To verify the feasibility and performance of the proposed circuit, a controller has been designed and fabricated in 0.5μm 5V/40V HVCMOS process. Experimental results show that, in the AC input range of 85V/60Hz~265V/60Hz, the power factor is greater than 95% and the efficiency is greater than 84.9% under full load which meets the design requirements.