Fluorescent tube driver circuit system of pulse-width modulation control

A dimmable fluorescent tube driver system, receiving a feedback signal for indicating an operating status of a fluorescent tube and driving the fluorescent tube in accordance with the feedback signal, the dimmable fluorescent tube driver system comprising:

• a frequency generator, receiving the feedback signal for determining and outputting a pulse signal with one of a first frequency and a second frequency;
• a power control signal generating device, receiving the pulse signal and outputting a first control signal and a second control signal in accordance with the pulse signal and the feedback signal;
• a protection circuit, receiving the feedback signal for determining whether or not to change the said first control signal and the said second control signal;
• a power switch circuit, receiving the first control signal and the second control signal, comprising:
• a first power switch controlled by the first control signal;
• a second power switch controlled by the second control signal;
• and
• a light-dimming device, receiving the feedback signal for determining whether or not to output a light-dimming signal.
• wherein both duty cycles of the first power switch and the second power switch are less than 50%.

A fluorescent tube driver circuit, comprising:

• a frequency generator, receiving a feedback signal which indicating an operating status of the fluorescent tube, and outputting a pulse signal with one of a first frequency and a second frequency;
• a power control signal generating device, receiving the pulse signal and outputting a set of control signals in accordance with the pulse signal and the feedback signal;
• and
• a power switch circuit comprising at least one switch, coupled to a power source and outputting an electric power of the power source in accordance with the set of control signals.