Led driver providing constant output power across a wide output voltage and current range

Abstract

An LED driver provides constant output power with wide range output current and voltage. A parallel resonant tank configuration is supplemented by resonant gain clamping circuit configured to partially cancel voltage across the resonant capacitor during half-bridge switching operation. Voltage between the resonant components is clamped to one-half a driver input voltage, ensuring inductive switching of the half-bridge. An output transformer has a primary winding coupled across the resonant capacitor, with a center tap defining first and second portions. An output voltage clamping circuit is coupled across the DC input power source and to the center tap, wherein maximum voltage across the primary is clamped based on a relationship between respective numbers of turns in the first and second portions, and maximum voltage across a secondary winding is clamped based on a relationship between the respective numbers of turns in the secondary winding and the first and second portions.