Circuits and methods for driving light sources

An electronic system comprising:

• a dimming controller configured to detect a dimming request signal indicative of an operation of a power switch, and operate in a mode selected from a first mode and a second mode to control dimming of a light source in response to said dimming request signal, wherein said light source comprises a first light element and a second light element;
• a buck-boost power converter coupled to said dimming controller, configured to provide power to said first light element when said dimmer controller operates in said first mode;
• a control circuit coupled to said dimming controller, configured to control said second light element to be powered on when said dimmer controller operates in said second mode,
• wherein during operation in said first mode, said dimming controller controls said control circuit to turn off said second light element and adjusts a first current flowing through said first light element, and wherein during operation in said second mode, said dimming controller conducts a current flowing through said control circuit and said second light element to turn on said second light element, and controls said first current to be cut off.

A method for adjusting power for a light source, comprising:

• receiving a switch monitoring signal indicative of a conductance status of a power switch coupled to a power source;
• selecting an operation mode from at least a first mode and a second mode according to said switch monitoring signal;
• controlling a control switch to operate at a first state and a second state alternately to adjust a first current flowing through a first light element to a target current if said first mode is selected;
• operating a control circuit coupled to a second light element to cut off a second current flowing through said second light element if said first mode is selected;
• conducting said second current flowing through said second light element if said second mode is selected;
• and
• cutting off said first current flowing through said first light element if said second mode is selected.