Controller and method for controlling dimming of light sources, and light source driving circuit

The present invention discloses a method of controlling an LED light source dimming controller and method and a driving circuit. The controller represents the size comparison between the current flowing through the LED light source induced signal and the reference signal to provide a pulse signal; when the PWM signal is in a first state, said controller controlling said pulse signal the current flowing through the LED light source; when the pulse width modulation signal is in a second state, said controller turns off the current flowing through the LED light source; a controller according to the received tone light adjusting the reference signal value of the request signal, and adjusting the duty cycle of the pulse width modulated signal to adjust the average current through the LED light source; wherein the dimming request signal is coupled to the AC power and represents operation of the power switch between the bridge rectifier. The present invention achieves a wider dimming range of the LED light source, to improve the energy efficiency.