Patent ID: 9006980
Filing Date: 2015-04-14
Classification: H05B

Abstract:
1. An apparatus for driving a fluorescent lamp, comprising: an LC resonator, for receiving and converting a square signal, so as to generate a sinusoidal driving signal for driving the fluorescent lamp; and an automatic frequency tracing circuit, coupled to the LC resonator, for making a frequency of the sinusoidal driving signal automatically following a resonant frequency of the LC resonator according to a feedback signal related to the sinusoidal driving signal, a power switching circuit, coupled between an input voltage and a ground potential, for switching and outputting the input voltage and the ground potential in response to a ramp signal and a comparison voltage, so as to generate the square signal, wherein the automatic frequency tracing circuit generates and adjusts the ramp signal according to the feedback signal related to the sinusoidal driving signal, so as to make the frequency of the sinusoidal driving signal automatically following the resonant frequency of the LC resonator, wherein the power switching circuit comprising a first comparator, having a negative input terminal receiving the ramp signal, a positive input terminal receiving the comparison voltage, and an output terminal outputting a first pulse width modulation signal; a phase-splitting circuit, coupled to the first comparator, for receiving the first pulse width modulation signal, and performing phase-splitting to the first pulse width modulation signal in response to a comparison signal, or directly performing the phase-splitting to the first pulse width modulation signal, so as to obtain two output signals with a phase difference of 180 degrees; a buffering circuit, coupled to the phase-splitting circuit, for receiving and buffering-outputting the two output signals; and a switching circuit, coupled between the input voltage and the ground potential and coupled to the buffering circuit, for switching and outputting the input voltage and the ground potential in response to the two buffered output signals, so as to generate the square signal.