A Novel Totem-pole Buck LED Driver With Minimal Power Processing

This paper proposes an totem-pole power factor correcting LED driver topology with minimal power processing. Minimal power processing is achieved through by-passing majority portion of the power directly to the load and process the minimum power required through a buck converter to maintain constant output current. As the power is processed only once and the usage of totem-pole topology improves the overall driver efficiency. The output power is maintained constant using two switches. One is used for by-passing the current directly from the source to the load and the other one is used to supply current from the storage capacitor to the load as per requirement. The required storage capacitor value is also very less when compare to standard LED driver capacitance. So, electrolytic capacitors are eliminated with film capacitors. The buck converter and PFC stage totem-pole boost converter both function in DCM. The DCM operation allows the use of much low valued inductor. As the totem-pole boost PFC stage is operated in DCM mode the power factor of the driver remains very close to unity. The proposed LED driver simulated at the power level of 60w.