A primary side controlled single-stage flyback LED driver with high power factor and high accuracy

A single stage flyback LED driver with high PF and high accuracy output current is proposed. High accuracy of the output current is achieved with average current control technology. High power factor is achieved by using adaptive turn on and constant turn off time strategy. Segmented startup strategy is adopted to ensure a fast startup phase. Fast startup can prevent the system from startup failure and provide better startup performance. A prototype on PCB has been designed to verify the control strategy. Test results shows the power factor is above 0.93. The current precision is below 3%.The system startup time is less than 1.5ms.