International Rectifier's IRS2983S LEDrivIR™ is a fully integrated, fully protected SMPS control IC designed to drive Flyback converter LED drivers. The IRS2983S features include primary side power regulation, which allows a basic converter to be implemented without the need for an opto isolator in a Flyback LED driver with a fixed load enabling a low cost, high reliability isolated LED driver design to be realized. The IRS2983S may also be used in converters that do include secondary feedback through an opto isolator. Other features of the IRS2983S include a high voltage startup enabling VCC supply to be derived initially from the high voltage DC bus until the auxiliary inductor winding is able to take over. The IRS2983S operates in critical conduction (CrCM) or discontinuous (DCM) modes and is fully protected against open and short circuit as well as inductor saturation. The IRS2983S may be used in single stage Flyback LED drivers with an unsmoothed DC bus to obtain high power factor and low THD.