Monolithic controller for single stage power factor correction with isolation and soft-switching

For offline power converters with power factor correction, single-stage step-down power conversion offers simplicity and high efficiency for medium to high power applications such as telecom power conversion. With the advent of faster, high voltage IGBTs, the isolated boost power converter with step-down (also known as the Clarke converter) is more feasible. A novel controller is presented which facilitates easy implementation of the isolated boost PFC operation with performance enhancements such as soft-switching with adaptive delays, a faster responding RMS input voltage detection circuit which eliminates an external 2-pole filter, safe start-up and no-load operation.