Combinational circuit and control circuit

1. A combinational circuit, applied to an LED drive circuit, comprising: a detection module and a drive and logic conversion module connected with the detection module, and wherein:

the detection module is configured to detect a state of an external switch, generate a detection signal according to the state of the external switch as detected, and send the detection signal to the drive and logic conversion module; and

the drive and logic conversion module is configured to receive the detection signal from the detection module, generate a driving signal according to the detection signal, and drive an operation state of a discharge module for discharging an output electrolytic capacitor of the LED drive circuit by using a state of the driving signal.

2. The combinational circuit according to claim 1 , wherein:

when the state of the external switch is OFF, the detection signal generated by the detection module according to the state of the external switch is a low level, the driving signal generated by the drive and logic conversion module according to the detection signal of the low level is a high level, and the discharge module is driven to work to discharge the output electrolytic capacitor of the LED drive circuit; and

when the state of the external switch is ON, the detection signal generated by the detection module according to the state of the external switch is a high level, the driving signal generated by the drive and logic conversion module according to the detection signal of the high level is a low level, and the discharge module does not work.

3. The combinational circuit according to claim 2 , wherein:

the detection module comprises a first resistor, a capacitor device, a diode, and an auxiliary winding of a power inductor, wherein the first resistor is connected in parallel with the capacitor device, and the diode and the auxiliary winding of the power inductor are connected in series and are connected in parallel with the capacitor device; and

when the state of the external switch is ON, a voltage on the auxiliary winding of the power inductor is a high-frequency pulsating alternating-current square wave, and the voltage on the auxiliary winding of the power inductor generates the detection signal of a high level after being rectified and filtered by the diode and the capacitor device; and

when the state of the external switch is OFF, the diode is turned off and the detection signal of a low level is generated.

4. The combinational circuit according to claim 3 , wherein:

the drive and logic conversion module comprises a zener diode and a MOS transistor, wherein one end of the zener diode is connected with the capacitor device, and the other end of the zener diode is connected with a gate electrode of the MOS transistor; and

when the detection signal generated by the detection module is a low level, the zener diode is turned off, the MOS transistor is turned off, the driving signal of a high level is generated and applied to the discharge module, and the output electrolytic capacitor is discharged through the discharge module; and

when the detection signal generated by the detection module is a high level, the zener diode is turned on and broken down, by which the MOS transistor is driven to turn on, and the driving signal of a low level is generated and applied to the discharge module, and the discharge module does not work.

5. A control circuit, applied to an LED drive circuit, comprising: a switch module, a discharge module, and the combinational circuit, and

wherein the combinational circuit comprises: a detection module and a drive and logic conversion module connected with the detection module, and wherein:

the detection module is configured to detect a state of an external switch, generate a detection signal according to the state of the external switch as detected, and send the detection signal to the drive and logic conversion module; and

the drive and logic conversion module is configured to receive the detection signal from the detection module, generate a driving signal according to the detection signal, and drive an operation state of a discharge module for discharging an output electrolytic capacitor of the LED drive circuit by using a state of the driving signal; and

wherein the switch module is connected with at least two sets of light sources, and is configured to receive a switching signal from an external switch and switch a color temperature and/or brightness of the at least two sets of light sources according to the switching signal; and

wherein the discharge module is respectively connected with the switch module and the drive and logic conversion module in the combinational circuit, and is configured to receive the driving signal output by the drive and logic conversion module, drive a self-state by using a state of the driving signal, and discharge the output electrolytic capacitor of the LED drive circuit upon the self-state being an operation state, so that the output electrolytic capacitor does not discharge through a light source which currently emits light, after the switch module switches the color temperature and/or brightness of the at least two sets of light sources.

6. The control circuit according to claim 5 , wherein the control circuit is used for controlling or eliminating flicker of light source upon the LED driving circuit switching the color temperature and/or brightness of the at least sets of two light sources by using a switch.

7. The control circuit according to claim 5 , wherein a condition for the external switch to generate the switching signal comprises: when a state of the external switch is ON, the switching signal is generated upon the external switch being turned off and then turned on.

8. The control circuit according to claim 5 , wherein:

the discharge module comprises a second resistor and a triode, one end of the second resistor is connected with a collector of the triode, the other end of the second resistor is connected with one end of the output electrolytic capacitor, and the other end of the output electrolytic capacitor is connected with an emitter of the triode; and

when a state of the external switch is OFF, the detection signal generated by the detection module of the combinational circuit according to the state of the external switch is a low level, the driving signal generated by the drive and logic conversion module according to the detection signal of a low level is a high level, the triode is driven to be conductive, and the output electrolytic capacitor is discharged through the second resistor and the triode.

9. The control circuit according to claim 5 , wherein the at least two sets of light sources comprise light sources of at least two colors, and different sets of the at least two sets of light sources have different colors.

10. The control circuit according to claim 5 , wherein different sets of the at least two sets of light sources have different numbers of light sources.

11. The control circuit according to claim 5 , wherein the at least two sets of light sources comprise light sources of at least two colors, and different sets of the at least two sets of light sources have different colors and different numbers of light sources.

12. The control circuit according to claim 5 , further comprising:

a linear voltage stabilizing source that is connected with the detection module of the combinational circuit, and is configured to receive the detection signal of the detection module and provide a stable voltage to the drive and logic conversion module according to the detection signal.

13. An LED drive circuit, comprising: a detection circuit and a drive and logic conversion circuit connected with the detection circuit, and wherein:

the detection circuit is configured to detect a state of an external switch, generate a detection signal according to the state of the external switch as detected, and send the detection signal to the drive and logic conversion circuit; and

the drive and logic conversion circuit is configured to receive the detection signal from the detection circuit, generate a driving signal according to the detection signal, and drive an operation state of a discharge circuit for discharging an output electrolytic capacitor of the LED drive circuit by using a state of the driving signal.

14. The LED drive circuit according to claim 13 , wherein:

when the state of the external switch is OFF, the detection signal generated by the detection circuit according to the state of the external switch is a low level, the driving signal generated by the drive and logic conversion circuit according to the detection signal of the low level is a high level, and the discharge circuit is driven to work to discharge the output electrolytic capacitor of the LED drive circuit; and

when the state of the external switch is ON, the detection signal generated by the detection circuit according to the state of the external switch is a high level, the driving signal generated by the drive and logic conversion circuit according to the detection signal of the high level is a low level, and the discharge circuit does not work.

15. The LED drive circuit according to claim 14 , wherein:

the detection circuit comprises a first resistor, a capacitor device, a diode, and an auxiliary winding of a power inductor, wherein the first resistor is connected in parallel with the capacitor device, and the diode and the auxiliary winding of the power inductor are connected in series and are connected in parallel with the capacitor device; and

when the state of the external switch is ON, a voltage on the auxiliary winding of the power inductor is a high-frequency pulsating alternating-current square wave, and the voltage on the auxiliary winding of the power inductor generates the detection signal of a high level after being rectified and filtered by the diode and the capacitor device; and

when the state of the external switch is OFF, the diode is turned off and the detection signal of a low level is generated.

16. The LED drive circuit according to claim 15 , wherein:

the drive and logic conversion circuit comprises a zener diode and a MOS transistor, wherein one end of the zener diode is connected with the capacitor device, and the other end of the zener diode is connected with a gate electrode of the MOS transistor; and

when the detection signal generated by the detection circuit is a low level, the zener diode is turned off, the MOS transistor is turned off, the driving signal of a high level is generated and applied to the discharge circuit, and the output electrolytic capacitor is discharged through the discharge circuit; and

when the detection signal generated by the detection circuit is a high level, the zener diode is turned on and broken down, by which the MOS transistor is driven to turn on, and the driving signal of a low level is generated and applied to the discharge circuit, and the discharge circuit does not work.