Abstract: The invention discloses a method and system to detect zero current conditions in a buck inductor by monitoring the voltage across the buck inductor. Once zero current and voltage conditions are present, an inverter circuit changes the operational state, i.e. conducting or non-conducting, of the switching transistors driving the lamps to reduce power loss associated with changing the operational state of switching transistors when under a load.

Abstract: An electronic ballast including a rectifying circuit to provide a signal representative of the current signal associated with a buck inductor, a monitoring circuit to provide a monitoring circuit signal when the signal representative of the buck inductor is within a specified range, and a comparing circuit coupled to the rectifying circuit and the monitoring circuit and operable to alter the output of the power converter circuit driving the lamps in response to comparisons between the signals from the rectifying circuit and the monitoring circuit to control power conditions in the ballasts.