Patent ID: 8598802

Claim:
A white light emitting diode (WLED) driving circuit, comprising: a Triac dimmer configured to receive an input alternating current (AC) supply voltage and to provide an output AC voltage having a plurality of regulated conduction angles; an electronic transformer configured to receive said output AC voltage and to convert said output AC voltage into a pulse width modulation (PWM) direct current (DC) voltage, wherein said PWM DC voltage having a duty cycle; a WLED driver configured to receive said PWM DC voltage and to provide a WLED driving signal; wherein said electronic transformer detects said plurality of regulated conduction angles of said output AC voltage and regulates the duty cycle of said PWM DC voltage based on said plurality of regulated conduction angles; a conduction angle detection module configured to detect said plurality of regulated conduction angles of said output AC voltage and generating a first PWM signal representing said plurality of regulated conduction angles; a conduction angle modulation module configured to receive said first PWM signal, and to generate a DC voltage signal which represents an average DC value of said first PWM signal, and said conduction angle modulation module configured to compare said DC voltage signal with a triangle waveform to generate a second PWM signal having a duty cycle and a frequency; and a conversion module configured to receive said output AC voltage and said second PWM signal, and to convert said output AC voltage into said PWM DC voltage in response to said second PWM signal.