Fairchild Korea Semiconductor Ltd.

Fairfield Korea Semiconductor Ltd.

Dae-Bong Kim

Nak-Choon Choi

Chang-Ho Kim

Kyung-Oun Jang

Dong-Myeong Shin

A lamp system including: a power-factor compensator, a current controller including first and second switches, the current controller being coupled to the on/off periods of the first and second switches for controlling the magnitude of a lamp driving current from the power-factor compensator; a lamp section including a resonance circuit composed of a resistor, an inductor and a capacitor, and emitting light under a current from the current controller; a ballast for forming a feedback voltage using a current flowing through the lamp section including soft start and dimming control. The lamp system compares the feedback voltage to a reference voltage to determine whether the current input to the lamp section is an overcurrent, an undercurrent, or a normal current. The ballast controls the on/off periods of the first and second switches.

Lamp system with electronic ballast

An electronic ballast for use in illuminating a lamp includes a lamp driving circuit having a pulse-width modulated signal generator, a timing capacitor coupled to the lamp driving circuit, and a power controller. The power controller uses a current sense resistor to detect a current flowing through the lamp and an operational amplifier circuit to compare a signal associated with the detected current to a reference voltage associated with a desired lamp current. Based on the comparison, the power controller provides a correction current to the timing capacitor to control a duty cycle of an output of the pulse-width modulated signal generator.

Electronic ballast system

Disclosed is an electric ballast system. The system comprises a voltage source for supplying power to the electric ballast system; a lamp driving circuit having a first terminal, a second terminal, and a third terminal, the power of the voltage source being supplied through the first terminal to begin the driving of the electric ballast system, and the lamp driving circuit outputting PWM waves through the second and third terminals; a half bridge converter, a first end of which is connected to the second terminal of the lamp driving circuit and a second end of which is connected to the third terminal of the lamp driving circuit, the half bridge converter receiving input through the second and third terminals of the lamp driving circuit, and the half bridge converter performing output of a current which changes flow directions according to the PWM waves output by the lamp driving circuit; a lamp portion, a first end of which is connected to an output end of the half bridge converter, the lamp operating according to the current output by the half bridge converter; and a lamp protector connected between a second end of the lamp and the first terminal of the lamp driving circuit, the lamp protector discontinuing the operation of the lamp driving circuit if there is no bulb installed in the lamp.

Electric ballast system

A switching power supply having a high efficiency starting circuit uses a field effect transistor to provide initial starting current to a pulse width modulated signal generator within a switching control circuit. The field effect transistor (FET) has a drain connected to a source of supply voltage, a source connected to the PWM signal generator, and a gate connected to a feedback voltage that is derived from an output voltage of the switching power supply. During start up of the switching power supply, the FET provides current to the PWM signal generator. When the feedback voltage reaches a predetermined level, the FET supplies substantially near zero current to the PWM signal generator, thereby eliminating the electrical inefficiencies typically associated with a conventional switching power supply starting circuit.

Growing community of inventors

Incheon, South Korea

Dae-Bong Kim