Abstract: In a post regulation control circuit mainly used in a switching power supply with several sets of outputs, the circuit adopts leading edge synchronization and conduction time regulation for the control, and a leading edge of the waveform of an input voltage of a detected secondary inductor generates a sync signal to reset a ramp generator to produce a stable continuous ramp signal, and compares with a feedback voltage to generate a power conduction signal corresponding to a stable output voltage. After the power conduction signal is cut off, a flywheel conduction signal in an inverted phase is produced. The two signals separately have an output terminal for driving two power switches of power conduction and flywheel conduction. The circuit applicable for various AC or DC step-down regulators gives a stable regulation control for the switching power supply with several alternating outputs.

Abstract: A feedback and protection circuit is provided for detecting voltage and current of a cold cathode fluorescent lamp (CCFL) of a liquid crystal display (LCD) panel backlight apparatus and integrating all voltage and current input signals to output single current and voltage feedback signals to a PWM controller, so as to stabilize and control the voltage and current of the CCFL and determine whether any detected input signal is abnormal. If any CCFL is short circuited (CCFL is touched by people) or open circuited (CCFL is not lit), an abnormal status protection signal will be produced and sent to the PWM controller to stop all outputs of the backlight apparatus to prevent damages to circuit components or injuries to people. The circuit is designed in an integrated circuit to achieve the effects of reducing the area occupied by the circuit component layout and lowering the overall cost.

Abstract: A feedback and protection circuit is provided for detecting voltage and current of a cold cathode fluorescent lamp (CCFL) of a liquid crystal display (LCD) panel backlight apparatus and integrating all voltage and current input signals to output single current and voltage feedback signals to a PWM controller, so as to stabilize and control the voltage and current of the CCFL and determine whether any detected input signal is abnormal. If any CCFL is short circuited (CCFL is touched by people) or open circuited (CCFL is not lit), an abnormal status protection signal will be produced and sent to the PWM controller to stop all outputs of the backlight apparatus to prevent damages to circuit components or injuries to people. The circuit is designed in an integrated circuit to achieve the effects of reducing the area occupied by the circuit component layout and lowering the overall cost.

Abstract: In a post regulation control circuit mainly used in a switching power supply with several sets of outputs, the circuit adopts leading edge synchronization and conduction time regulation for the control, and a leading edge of the waveform of an input voltage of a detected secondary inductor generates a sync signal to reset a ramp generator to produce a stable continuous ramp signal, and compares with a feedback voltage to generate a power conduction signal corresponding to a stable output voltage. After the power conduction signal is cut off, a flywheel conduction signal in an inverted phase is produced. The two signals separately have an output terminal for driving two power switches of power conduction and flywheel conduction. The circuit applicable for various AC or DC step-down regulators gives a stable regulation control for the switching power supply with several alternating outputs.

Abstract: The present invention discloses a primary-side feedback switching power supply that uses a sample-and-hold circuit to obtain a corner voltage of a harmonic wave voltage while the primary-side auxiliary winding is operating at a discontinuous mode as a feedback control, and provides both voltage regulation and current limit functions. A stable voltage output is provided within the nominal input voltage and nominal output load, such that when the output reaches a current limit, the output voltage drops but the output current is controlled to remain unchanged, so as to provide an over-current protection.

Abstract: The present invention provides a light source driver circuit for improving power conversion efficiency and avoiding a high cost due to the requirements of safety regulations. The light source driver circuit comprises a pulse width control circuit that uses an AC power supply to produce a square wave; a first transformer having a primary winding for inputting the square wave and a secondary winding for outputting a transformation square wave; a resonant circuit that inputs the transformation square wave for producing a resonance sine wave; and a second transformer having a primary winding for inputting the resonance sine wave and a secondary winding for outputting a transformation sine wave to drive a light source.