Abstract: A power supply protected against open circuit conditions at its output terminals, and methods for so protecting, are disclosed. A front end circuit receives an input voltage and provides a regulated front end DC voltage to a voltage converter circuit, which in turn provides a DC output voltage to the output terminals to drive a light source. An open circuit protection circuit is coupled between the voltage converter circuit and the output terminals. It has a non-conducting state to couple the DC output voltage to the output terminals, and a conducting state to establish a short circuit across the output terminals in response to charging of a capacitor during an open circuit condition at the output terminals. A restart circuit intermittently discharges the capacitor during the open circuit condition to place the open circuit protection circuit in the non-conducting state when the open circuit condition is resolved.

Abstract: A ballast comprises an inverter circuit for providing an oscillating current signal for energizing the at least one lamp. The inverter circuit comprises a first switching component and a second switching component each having a collector terminal, a base terminal, and an emitter terminal. And, each switching component is configured for alternately operating between a conductive state and a non-conductive state. A first collector-emitter circuit is connected between the collector terminal and the emitter terminal of the first switching component, wherein the first collector-emitter circuit has a first resistance of zero or more Ohms. A second collector-emitter circuit is connected between the collector terminal and the emitter terminal of the second switching component, wherein the second collector-emitter circuit has a second resistance of zero or more Ohms and the first resistance and the second resistance are unequal.