Design of Off-line Flyback LED Constant Current Converter

LED is recognized as the next generation of lighting source.When it is faced with consumers,a high efficiency low cost constant current converter is usually demanded.Adopting discontinuous conduction mode(DCM),a practical approach to the design of an off-line flyback constant current source is proposed in this article,which is low cost,high efficient and electrically safe.The output current is held constant within the normal operating range.However,if the load is cut off,the output voltage will be held constant at the default maximum value.Thus the output stage on the secondary side is protected.