Patent ID: 7859194

Claim:
A system comprising: a transformer having primary and secondary windings; a trigger power supply having first and second terminals; a trigger circuit including the primary winding of the transformer and a trigger capacitor coupled to be charged by the trigger power supply; a main power supply having first and second terminals; a bulk energy storage capacitor coupled to the first and second terminals of the main power supply to be charged by the main power supply; a boost capacitor; a first diode coupling the first terminal of the trigger power supply to the boost capacitor in the forward conducting direction; a second diode isolating the first terminal of the main power supply from the boost capacitor; first and second nodes adapted to be coupled to the terminals of a gas discharge lamp, with the bulk energy storage capacitor and the boost capacitor coupled to the first node via the secondary winding of the transformer; a current limiting element, having a control input adapted to receive an ON signal, coupling one of said nodes to a terminal of the main power supply, that conducts current when a received ON signal is asserted; a feedback element coupled to a node to output a first current level value indicating the magnitude of current passed through the current limiting element; a current level control unit that outputs a second current level; and a source control unit, having a first input coupled to the feedback element, a second input coupled to the current level control unit, and an output coupled to the control input, that asserts an ON signal when the first current level value is less than the second current level.