Abstract: An electronic ballast and startup method including an electronic ballast operably connected to a lamp having a lamp filament, the electronic ballast having a timer (110) generating an inverter control signal (112) and a preheat control signal (114); a converter (120) receiving AC power and generating DC power (122); a self-oscillating inverter (130) receiving DC power (122) and being operable to provide lamp power (132) to the lamp, the self-oscillating inverter (130) being responsive to the inverter control signal (112); and a filament preheater (140) receiving DC power (122) and being operable to provide filament power (142) to the lamp filament, the filament preheater (140) being responsive to the preheat control signal (114). When AC power is initially applied, preheat control signal (114) directs the filament preheater (140) to provide filament power (142), and inverter control signal (112) directs the self-oscillating inverter (130) not to provide lamp power (132).

Abstract: An electronic ballast and startup method including an electronic ballast operably connected to a lamp having a lamp filament, the electronic ballast having a timer (110) generating an inverter control signal (112) and a preheat control signal (114); a converter (120) receiving AC power and generating DC power (122); a self-oscillating inverter (130) receiving DC power (122) and being operable to provide lamp power (132) to the lamp, the self-oscillating inverter (130) being responsive to the inverter control signal (112); and a filament preheater (140) receiving DC power (122) and being operable to provide filament power (142) to the lamp filament, the filament preheater (140) being responsive to the preheat control signal (114). When AC power is initially applied, preheat control signal (114) directs the filament preheater (140) to provide filament power (142), and inverter control signal (112) directs the self-oscillating inverter (130) not to provide lamp power (132).

Abstract: A software controlled electronic dimming ballast for preheating, striking, and varying the dimming level of a lamp. In one embodiment, the ballast includes an EMI filter circuit, an AC/DC converter circuit, a PFC circuit, an inverter circuit, and a software controlled microcontroller circuit. The microcontroller circuit includes a microcontroller and software for generating inverter control signals that cause the inverter circuit to preheat, strike, and varying the dimming level of the lamp. The inverter control signals are generated based on dimming control and lamp dimming level feedback signals. The ballast also includes a lamp dimming level feedback signal conditioning circuit for generating the lamp dimming level feedback signals. Alternative embodiments of the ballast are also described.

Abstract: A software controlled electronic dimming ballast for preheating, striking, and varying the dimming level of a lamp. In one embodiment, the ballast includes an EMI filter circuit, an AC/DC converter circuit, a PFC circuit, an inverter circuit, and a software controlled microcontroller circuit. The microcontroller circuit includes a microcontroller and software for generating inverter control signals that cause the inverter circuit to preheat, strike, and varying the dimming level of the lamp. The inverter control signals are generated based on dimming control and lamp dimming level feedback signals. The ballast also includes a lamp dimming level feedback signal conditioning circuit for generating the lamp dimming level feedback signals. Alternative embodiments of the ballast are also described.

Abstract: A software controlled electronic dimming ballast for preheating, striking, and varying the dimming level of a lamp. In one embodiment, the ballast includes an EMI filter circuit, an AC/DC converter circuit, a PFC circuit, an inverter circuit, and a software controlled microcontroller circuit. The microcontroller circuit includes a microcontroller and software for generating inverter control signals that cause the inverter circuit to preheat, strike, and varying the dimming level of the lamp. The inverter control signals are generated based on dimming control and lamp dimming level feedback signals. The ballast also includes a lamp dimming level feedback signal conditioning circuit for generating the lamp dimming level feedback signals. Alternative embodiments of the ballast are also described.

Abstract: An electronic ballast includes open circuit voltage regulation comprises an filament current sensing circuit 224 operably connected to an output of the electronic ballast and generating a sensed output voltage signal, and a regulating pulse width modulator U3 receiving the sensed output voltage signal and operably connected to control voltage at the output of the electronic ballast, the regulating pulse width modulator U3 having an output voltage threshold limit. The regulating pulse width modulator U3 limits the voltage at the output of the electronic ballast when the sensed output voltage signal exceeds the output voltage threshold limit. The regulating pulse width modulator U3 can limit the output voltage by limiting the pulse width to the high voltage driver and the resonant half bridge. The filament current sensing circuit 224 can sense the output voltage indirectly, such as by sensing tank current, or can sense the output voltage directly.

Abstract: A software controlled electronic dimming ballast for preheating, striking, and varying the dimming level of a lamp. In one embodiment, the ballast includes an EMI filter circuit, an AC/DC converter circuit, a PFC circuit, an inverter circuit, and a software controlled microcontroller circuit. The microcontroller circuit includes a microcontroller and software for generating inverter control signals that cause the inverter circuit to preheat, strike, and varying the dimming level of the lamp. The inverter control signals are generated based on dimming control and lamp dimming level feedback signals. The ballast also includes a lamp dimming level feedback signal conditioning circuit for generating the lamp dimming level feedback signals. Alternative embodiments of the ballast are also described.