Light source driving circuits and light source module

1. A light source driving circuit comprising:

a rectifier operable for rectifying a voltage from a power source and providing a rectified voltage;

a power converter, coupled to said rectifier, operable for receiving said rectified voltage and providing an output current; and

a light source module, coupled to said power converter and powered by said output current, comprising:

a first light source having a first color;

a second light source having a second color; and

a current allocation unit, coupled to said first light source and said second light source, operable for adjusting a current through said first light source and a current through said second light source based on said output current,

wherein said current allocation unit comprises:

a sensing unit, coupled to said first light source and said second light source, operable for providing a sensing signal indicating said output current;

a control unit coupled to said sensing unit; and

a current regulation unit coupled to said first light source,

wherein said control unit is operable for controlling said current regulation unit based on said sensing signal to regulate said current through said first light source,

wherein said control unit comprises an operational amplifier, wherein said current regulation unit comprises a second switch coupled in series with said first light source,

wherein a first input terminal of said operational amplifier receives a reference signal, a second input terminal of said operational amplifier is coupled to said sensing unit through a second resistor to receive said sensing signal, and an output terminal of said operational amplifier is coupled to said second switch,

wherein said operational amplifier is operable for adjusting said current through said first light source by controlling said second switch.

2. The light source driving circuit of claim 1 , further comprising:

a controller, coupled to said power converter, operable for monitoring a power switch coupled between said power source and said light source driving circuit, operable for receiving a dimming request signal indicating a first set of operations of said power switch and a dimming termination signal indicating a second set of operations of said power switch, operable for adjusting said output current in response to said dimming request signal, and operable for stop adjusting said output current in response to said dimming termination signal.

3. The light source driving circuit of claim 2 , wherein said controller maintains said output current unchanged during a predetermined time period before adjusting said output current.

4. The light source driving circuit of claim 2 , wherein said first set of operations of said power switch comprises a first turn-on operation, wherein said second set of operations of said power switch comprises a first turn-off operation followed by a second turn-on operation.

5. The light source driving circuit of claim 2 , wherein said controller comprises:

a dimming unit, operable for generating a dimming signal based on said dimming request signal and said dimming termination signal, wherein said controller is operable for adjusting said output current based on said dimming signal.

6. The light source driving circuit of claim 5 , wherein said dimming unit comprises:

a trigger monitoring unit, operable for receiving said dimming request signal and said dimming termination signal and generating an enable signal;

a timer, operable for measuring time under control of said enable signal; and

a D/A converter, operable for generating said dimming signal based on an output of said timer.

7. The light source driving circuit of claim 5 , further comprising:

an energy storage unit coupled between said rectifier and said light source module;

a current sensor coupled to said energy storage unit, operable for generating a first signal indicating an instant current flowing through said energy storage unit; and

a filter, coupled to said current sensor, operable for generating a second signal based on said first signal, said second signal indicating an average current flowing through said energy storage unit,

wherein said controller is operable for adjusting said output current by controlling a first switch coupled between said rectifier and said energy storage unit.

8. The light source driving circuit of claim 7 , wherein said controller further comprises:

a saw-tooth signal generator, operable for generating a saw-tooth signal; and

an error amplifier, operable for generating an error signal based on said second signal and said dimming signal,

wherein if a voltage of said saw-tooth signal increases to a voltage of said error signal, said controller turns off said first switch.

9. The light source driving circuit of claim 8 , wherein said controller further comprises:

a reset signal generator operable for generating a reset signal, wherein said controller turns on said first switch in response to said reset signal.

10. The light source driving circuit of claim 1 , further comprising:

a controller, coupled to said power converter, operable for receiving a switch monitoring signal and adjusting said output current based on said switch monitoring signal, wherein said switch monitoring signal indicates a set of operations of a power switch coupled between said power source and said light source driving circuit.

11. The light source driving circuit of claim 10 , wherein said output current has a first level after a first turn-on operation of said power switch,

wherein if said switch monitoring signal indicates that said set of operations of said power switch comprises a first turn-off operation followed by a second turn-on operation, said controller adjusts said output current from said first level to a second level.

12. The light source driving circuit of claim 10 , wherein said controller comprises:

a dimming unit, operable for generating a dimming signal based on said switch monitoring signal, wherein said controller is operable for adjusting said output current based on said dimming signal.

13. The light source driving circuit of claim 12 , wherein said dimming unit comprises:

a trigger monitoring unit, operable for receiving said switch monitoring signal and generating a driving signal;

a counter driven by said driving signal, operable for generating a counter value; and

a D/A converter, operable for generating said dimming signal based on said counter value.

14. The light source driving circuit of claim 12 , further comprising:

an energy storage unit coupled between said rectifier and said light source module;

a current sensor coupled to said energy storage unit, operable for generating a first signal indicating an instant current flowing through said energy storage unit; and

a filter, coupled to said current sensor, operable for generating a second signal based on said first signal, said second signal indicating an average current flowing through said energy storage unit,

wherein said controller is operable for adjusting said output current by controlling a first switch coupled between said rectifier and said energy storage unit.

15. The light source driving circuit of claim 14 , wherein said controller further comprises:

a saw-tooth signal generator, operable for generating a saw-tooth signal; and

an error amplifier, operable for generating an error signal based on said second signal and said dimming signal,

wherein if a voltage of said saw-tooth signal increases to a voltage of said error signal, said controller turns off said first switch.

16. The light source driving circuit of claim 15 , wherein said controller further comprises:

a reset signal generator operable for generating a reset signal, wherein said controller turns on said first switch in response to said reset signal.

17. The light source driving circuit of claim 1 , wherein said first light source comprises a first LED string and said second light source comprises a second LED string, wherein a forward voltage of said first LED string is less than a forward voltage of said second LED string.

18. The light source driving circuit of claim 1 , wherein said sensing unit comprises:

a first resistor,

wherein said current through said first light source and said current through said second light source both flow through said first resistor.

19. A light source module comprising:

a first light source having a first color;

a second light source having a second color; and

a current allocation unit, coupled to said first light source and said second light source, operable for adjusting a current through said first light source and a current through said second light source based on an input current of said light source module,

wherein said current allocation unit comprises:

a sensing unit, coupled to said first light source and said second light source, operable for providing a sensing signal indicating said input current;

a control unit coupled to said sensing unit; and

a current regulation unit coupled to said first light source,

wherein said control unit is operable for controlling said current regulation unit based on said sensing signal to regulate said current through said first light source,

wherein said control unit comprises an operational amplifier, wherein said current regulation unit comprises a second switch coupled in series with said first light source,

wherein a first input terminal of said operational amplifier receives a reference signal, a second input terminal of said operational amplifier is coupled to said sensing unit through a second resistor to receive said sensing signal, and an output terminal of said operational amplifier is coupled to said second switch,

wherein said operational amplifier is operable for adjusting said current through said first light source by controlling said second switch.

20. The light source module of claim 19 , wherein said first light source comprises a first LED string and said second light source comprises a second LED string, wherein a forward voltage of said first LED string is less than a forward voltage of said second LED string.

21. The light source module of claim 19 , wherein said sensing unit comprises:

a first resistor,

wherein said current through said first light source and said current through said second light source both flow through said first resistor.