A Design Of Power Management Chip With Power Factor Correction

With global warming, energy saving and emission reduction has become the focus the world. Lighting, as an important field of energy consumption, is in urgent need of the introduction of new technology. And LED is the right choice of lighting, because of its low heat flux, low power consumption and environmental protection. As the key technology of LED lighting, the demand of drive circuit has been rapidly growing.We design a LED drive chip, using flyback methodology switching power supply technology, to realize the isolation from the input to the output. The power supply can be directly connected to the commercial power supply. We design this chip to achieve two functions: power factor correction and constant current output. By the special design of the control loop and primary side current sampling technology, we simplifies the peripheral circuit, effectively reduce the cost. The output current can be adjusted by peripheral sampling resistance.The core of the control circuit is: the primary side current sampling circuit, realizing the sampling of resistor voltage and latching of peak current; Current operation circuit, completing the operation of primary side current based on the Buck topology; Error amplifier, to ensure the stability of the loop, and determine the output current expression; Multiplier is designed to provide half wave envelope; PWM comparator, to compare between the primary side current and the input voltage, to realize power factor correction.In this thesis, we design the control loop: current operation circuit, error amplifier, primary side current sampling circuit, and bandgap reference. Finally through simulation of the whole chip, our chip achieved the designed function.