US Patent 9894718 Constant current source LED driver circuit with self-clamped output

A driver circuit provides current to a light source from a resonant tank having a single inductive element. The driver circuit is coupled to DC power source having a power rail and a ground, and includes a power inverter providing AC input to the tank, which further includes a DC blocking capacitor and a primary winding of the inductive element coupled in series between the output of the inverter and the ground. A leakage inductance of the inductive element provides resonant inductance for the tank. The inductive element further distributes power output from the resonant tank to a plurality of secondary windings coupled to an output rectifier. A resonant capacitor coupled across output ends of the secondary windings provides resonant capacitance for the tank. The output voltages across the secondary windings are clamped to a value based in part on a turns ratio between respective secondary windings.