LIGHTING SYSTEM AND CONTROL METHOD THEREOF

摘要

A lighting system includes: a rectifier full-wave rectified an AC voltage to generate an output voltage; first and second LED groups connected to each other in series, wherein an input terminal of the first LED group is coupled to the output voltage; first terminals of first and second switches respectively coupled to output terminals of the first and second LED groups; a first resistor having a first terminal connected to the second terminal of the first switch and the second switch and a second terminal connected to a ground voltage; and first and second operational amplifiers having output terminals respectively coupled to control terminals of the first and second switches, and inverting input terminals respectively coupled to the first terminal of the first resistor, and non-inverting input terminals respectively coupled to the first and second reference voltages.

主权项

1. A lighting system, comprising:
a rectifier, configured to perform full-wave rectification on an alternating current (AC) voltage to generate an output voltage; a first light emitting diode (LED) group and a second light emitting diode (LED) group connected in series to each other, wherein an input terminal of the first LED group is coupled to the output voltage; a first switch, having a first terminal coupled to an output terminal of the first LED group; a second switch, having a first terminal coupled to an output terminal of the second LED group; a first resistor, having a first terminal coupled to a second terminal of the first switch and a second terminal, of the second switch, and a second terminal coupled to a ground voltage; a first operational amplifier, having an output terminal coupled to a control terminal of the first switch, and an inverting input terminal coupled to the first terminal of the first resistor, and a non-inverting input terminal coupled to a first reference voltage; and a second operational amplifier, having an output terminal coupled to a control terminal of the second switch, and an inverting input terminal coupled to the first terminal of the first resistor, and a non-inverting input terminal coupled to a second reference voltage, wherein the first reference voltage is higher than the ground voltage and the second reference voltage is higher than the first reference voltage.