Abstract: An apparatus and method for powering a lamp connected to a ballast circuit. The ballast circuit is connected to a first alternating current (AC) source having a first phase and to a second AC source having a second phase. A first rectifier circuit is connected between the first AC source and a first switching circuit. A second rectifier circuit is connected between the second AC source and a first switching circuit. A control circuit selectively energizes the first and second switching circuits to provide power from the first and second AC sources to the lamp load via an inverter circuit. A detection circuit generates a detection signal indicating whether power is being supplied by each the first and second AC sources. The detection signal is provided to a dimming regulation circuit to generate a dim level command signal for dimming the lamp.

Abstract: An apparatus for detecting the reconnection of a lamp filament to an electronic ballast driving a fluorescent lamp. A control circuit controls an inverter circuit to providing power to a filament control circuit. The filament control circuit preheats and powers the lamp filament of the one or more lamps. A pulse generator generates an input signal as a function of the number of lamp filament connected to the filament control circuit. A current sensor generates a first voltage indicative of whether a lamp filament has been reconnected to the circuit. A peak detector generates a peak voltage signal when the first voltage indicates a reconnection of a lamp filament has occurred. A sensing circuit generates a command signal to provide to the control circuit to supply power to the filament control circuit to preheat and power the lamp when the peak detector generates the peak voltage signal.

Abstract: An apparatus and method for powering a lamp connected to a ballast circuit. The ballast circuit is connected to a first alternating current (AC) source having a first phase and to a second AC source having a second phase for powering the lamp. A first switching circuit is connected between the first AC source and a rectifier circuit. A second switching circuit is connected between the second AC source and the rectifier circuit. A control circuit selectively energizes the first and second switching circuits to provide power from one of the first and second AC sources to the lamp load via the rectifier circuit and an inverter circuit. A detection circuit connected between the first and second AC sources generates a detection signal indicating whether power is being supplied by each the first and second AC sources. The detection signal is provided to a dimming regulation circuit to generate a dim level command signal for dimming the lamp.

Abstract: A ballast (10) for powering a gas discharge lamp load (30) comprises an inverter (100), an output circuit (200), and a fault detection circuit (300). During operation, fault detection circuit (300) monitors a first signal and a second signal within output circuit (300) and sets a fault threshold in dependence on the second signal. The second signal is indicative of the type of lamps in the load (30). In response to the first signal exceeding the fault threshold, fault detection circuit (300) issues a shutdown command directing the inverter (100) to cease operation.