Abstract: A bridgeless interleaved power factor correction (PFC) circuit using a single PFC choke having four windings formed on a single core to form the four input inductors of the PFC circuit. An AC-to-DC converter constructed using the bridgeless interleaved PFC circuit achieves high conversion efficiency with high power factor and low total harmonic distortion. Furthermore, the size of the PFC circuit is reduced by using a single PFC choke with quad-winding.

Abstract: An LLC resonant converter implements a primary-side current feedback scheme. The LLC resonant converter includes an isolation transformer having a primary winding and at least one secondary winding and is controlled by a control circuit to operate at a switching frequency. The LLC resonant converter includes a first capacitor connected to the primary winding through AC coupling to sense a first voltage indicative of a current flowing through the primary winding of the isolation transformer, and a current sense circuit configured to receive the first voltage and to generate a feedback signal. The feedback signal is coupled to the control circuit to regulate the switching frequency in response to the current at the primary winding. In another embodiment, the current sense circuit is a current and voltage sense circuit configured to sense a voltage at the primary winding.

Abstract: A bridgeless interleaved power factor correction (PFC) circuit using a single PFC choke having four windings formed on a single core to form the four input inductors of the PFC circuit. An AC-to-DC converter constructed using the bridgeless interleaved PFC circuit achieves high conversion efficiency with high power factor and low total harmonic distortion.