The control-loop design of quasi-resonant flyback converter for HI-bright LED driver

This paper presents a HI-bright LED driver based on quasi-resonant flyback converter. With the DC/DC converters operating in valley switching mode, the converter approaches low EMI and high efficiency. The paper results in a control-to-output transfer function of the system close to that of a quasi-resonant flyback converter for ease of feedback loop design. By designing the parameters of the control loop, the driver achieves a output mode of constant current and constant voltage. Design considerations and experimental results are presented for 40W LED driver, demonstrating high power factor and high efficiency.