Patent ID: 9119257
Filing Date: 2015-08-25
Classification: H05B

Abstract:
1. A dimming circuit for a use of driving a light-emitting diode unit, and the dimming circuit comprising: a control unit, receiving and determining whether a duty ratio of a first pulse width modulation signal is larger than a threshold duty ratio; a sampling analysis unit, receiving and analyzing the first pulse width modulation signal and outputting a pulse information signal; a pulse width signal adjusting unit coupled between the control unit and a current regulation unit to receive the pulse information signal; and an analog dimming circuit coupled between the control unit and the current regulation unit, receiving the pulse information signal, wherein when the duty ratio of the first pulse width modulation signal is smaller than the threshold duty ratio, the pulse width signal adjusting unit transforms the first pulse width modulation signal to at least a second pulse width modulation signal by a frequency conversion and a phase shift according to the pulse information signal, and the analog dimming circuit outputs a predetermined dimming current, wherein when the duty ratio of the first pulse width modulation signal is larger than the threshold duty ratio, the analog dimming circuit adjusts the predetermined dimming current according to the pulse information signal, and outputs the second pulse width modulation signal having a 100% duty ratio.