ST power factor correction controllers operate in transition mode (TM) and continuous current mode (CCM), and are suitable for a wide-range-mains operation. In systems where high current capability (provided by CCM operation) and the affordability of TM operation are both required, ST proposes a third solution based on a proprietary and patented solution: fixed off time (FOT). This method is based on a simple modification of a standard TM PFC controller operation, and requires just a few additional passive parts with no significant extra costs.
All transition mode PFC controllers have an internal multiplier that significantly reduces the internal total harmonic distortion (THD), making SMPS more efficient and thus compliant with EN61000-3-2 and other energy-saving regulations.
These devices embed advanced protection features, which make SMPS more robust and compact, requiring fewer external components. These features include output overvoltage, brown-out, feedback disconnection and boost inductor saturation protection.
The high voltage start-up capability, present in the L6564H and L6563H, helps improve the SMPS standby efficiency in systems that do not include the auxiliary power supply.