Patent ID: 8957606
Filing Date: 2015-02-17
Classification: H05B

Abstract:
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.