TWI549566B - Dimming circuit - Google Patents

Description

Dimming circuit

The invention relates to a dimming circuit, which can be applied to a dimming circuit of an alternating current to direct current or a direct current to direct current conversion circuit.

With the popularization of environmental protection awareness, energy saving and carbon saving have become an important issue in the development of the electronics industry. For a lighting device, a light emitting diode (LED) has the advantages of long life, low power consumption, and low damage, so that the light emitting diode gradually replaces the old light. Components are gradually becoming popular among various electronic products.

Although the light-emitting diode has the above advantages, the light-emitting diode also has its disadvantages. Compared with the old light-emitting elements, the light emitted by the light-emitting diodes is obviously not so natural, and the light emitted by the old light-emitting elements is generally accepted by the general public. In order to respond to a variety of commercial applications, such as different display lights for different products, there is a need for a dimming circuit that can adjust the color temperature of the LEDs in response to the need.

In view of the above, the present invention is directed to a dimming circuit that solves the aforementioned two-pole by controlling multiple sets of light-emitting diodes to alternately illuminate to mix a light source having a desired average color temperature. Problems and needs in application begging.

The invention provides a dimming circuit, which has a main switch module, a first lighting module, an inductor, a sub-switch module and a second lighting module. The sub-switch module is electrically connected to the inductor, and the second lighting module is electrically connected to the sub-switch module. The main switch module selectively turns on the first current path according to the control signal. When the current flows through the first current path, the first light emitting module emits light at a first color temperature. The inductor stores energy as current flows through the first current path. When the current does not flow through the first current path, the inductor releases energy. When the inductor is released, the sub-switch module is driven by the inductor to conduct the second current path. When the current flows through the second current path, the second light emitting module emits light at the second color temperature. The first current path includes a first lighting module, an inductor, and a main switch module, and the second current path includes a second lighting module, an inductor, and a sub-switch module.

In summary, the present invention discloses a dimming circuit, which includes a first lighting module, a second lighting module, and a corresponding main switch module, a sub-switch module, and an inductor. The first lighting module, the inductor and the main switch module form a first current path, and the second lighting module, the inductor and the sub-switch module form a second current path, thereby controlling the first lighting module and the second The light emitting modules alternately emit light. And the first light-emitting module and the second light-emitting module respectively emit light at a first color temperature and a second color temperature, thereby mixing light having a desired color temperature.

The above description of the present invention and the following description of the embodiments are intended to illustrate and clarify the spirit and principles of the invention, and to provide further explanation of the scope of the invention.

1‧‧‧ dimming circuit

12‧‧‧First lighting module

122, 124, 126‧‧‧Lighting diodes

14‧‧‧Second lighting module

142, 144, 146‧‧‧Lighting diodes

148‧‧‧protection unit

16‧‧‧Inductance

160‧‧‧Detection resistance

17‧‧‧Voltage unit

172‧‧‧First resistance

174‧‧‧second resistance

18‧‧‧Control Module

D1, D2‧‧‧ protection unit

I _L ‧‧‧current

N1, N4‧‧‧ first end

N2, N5‧‧‧ second end

N3, N6‧‧‧ control terminal

N7‧‧‧ first input

N8‧‧‧ first output

N9‧‧‧ second input

N10‧‧‧ second output

N11‧‧‧first inductor

N12‧‧‧second inductor

N13‧‧‧first resistance end

N14‧‧‧second resistance

SW1‧‧‧ main switch module

SW2‧‧‧ sub-switch module

V _S ‧‧‧ control signal

V _L , V _R ‧‧‧ voltage

2‧‧‧Power supply

1A is a circuit diagram of a dimming circuit in an embodiment of the present invention.

FIG. 1B is a timing diagram of signals of a dimming circuit in an embodiment of the present invention.

1C is a schematic diagram of a first current path of a dimming circuit in an embodiment of the present invention.

1D is a schematic diagram of a second current path of a dimming circuit in an embodiment of the present invention.

2 is a circuit diagram of a dimming circuit in another embodiment of the present invention.

Figure 3 is a circuit diagram of a dimming circuit in a further embodiment of the present invention.

Figure 4 is a circuit diagram of a dimming circuit in still another embodiment of the present invention.

Figure 5 is a circuit diagram of a dimming circuit in still another embodiment of the present invention.

Figure 6 is a circuit diagram showing another embodiment of the dimming circuit of Figure 1A.

The detailed features of the present invention are described in the following description, which is sufficient for any skilled person to understand the technical contents of the present invention and to implement it, and according to the contents disclosed in the specification, the patent application scope and the drawings, any familiarity The related objects and advantages of the present invention will be readily understood by those skilled in the art. The following examples are intended to further illustrate the invention, but are not intended to limit the scope of the invention.

Please refer to FIG. 1A first, and FIG. 1A is an embodiment of the present invention. Schematic diagram of the optical circuit. As shown in FIG. 1A, the dimming circuit 1 according to an embodiment of the invention has a main switch module SW1, a sub-switch module SW2, a first light-emitting module 12, a second light-emitting module 14, an inductor 16 and a control module. Group 18.

In more detail, the main switch module SW1 has a first end N1, a second end N2 and a control end N3, and the sub-switch module SW2 has a first end N4, a second end N5 and a control end N6. The first lighting module 12 has a first input end N7 and a first output end N8, and the second lighting module 14 has a second input end N9 and a second output end N10. The inductor 16 has a first inductor terminal N11 and a second inductor terminal N12. The dimming circuit 1 is electrically connected to the power source 2 and receives power from the power source 2. The power source 2 is, for example, a DC power source such as a battery, an output power of an AC-DC converter, or an output power of a DC-DC converter.

The first terminal N1, the control terminal N6, the second inductor terminal N12 and the second input terminal N9 are electrically connected to each other. The second end N2 is electrically connected to the power source 2, and the control end N3 is electrically connected to the control module 18. The first end N4, the first input end N7, the second output end N10 and the power source 2 are electrically connected to each other. The second end N5, the first output end N8 and the first inductive end N11 of the inductor 16 are electrically connected to each other.

The main switch module SW1 is selectively turned on according to the control signal V _S . The control signal V _{S is,} for example, a pulse width modu-lation (PWM) signal. The main switch module SW1 is correspondingly turned on according to the voltage level of the pulse width modulation signal and its duty cycle change, and the operation will be described later. In addition, when the main switch module SW1 is turned on, current flows through the first current path in the dimming circuit 1. When the main switch module SW1 is not turned on, current flows through the second current path in the dimming circuit 1. The component that passes through the first current path includes the first light emitting module 12, the inductor 16 and the main switch module SW1. The component that passes through the second current path includes the second light emitting module 14, the inductor 16 and the sub-switch module SW2. In one embodiment, the main switch module SW1 is, for example, an N type Met-al-Oxide-Semiconductor Field-Effect Transistor (N-type MOSFET, NMOS).

The control module 18 is used to generate the control signal V _S , and the control module 18 is, for example, an integrated circuit (IC), but is not limited thereto. In another embodiment, the dimming circuit 1 does not include the control module 18, but directly receives the control signal V _S directly from the external circuit or device, that is, the control terminal N3 of the main switch module SW1 is electrically connected to the external circuit. Or device.

The first light emitting module 12 includes the light emitting diodes 122, 124, and 126. The light emitting diodes 124 are connected in series between the light emitting diodes 122 and 126, and one end of the light emitting diode 126 is the first light emitting module 12 The first input terminal N7 of the first LED N is a first output terminal N8 of the first LED module 12 . When current flows through the first light emitting module 12, the first light emitting module 12 emits light at a first color temperature.

Similarly, the second lighting module 14 includes a plurality of LEDs 142, 144, 146. The light emitting diode 144 is connected in series between the light emitting diodes 142 and 146, and one end of the light emitting diode 146 is the second output end N10 of the second light emitting module 14 , and one end of the light emitting diode 142 is the first The second input end N9 of the second light emitting module 14. When the current flows through the second light emitting module 14, the second light emitting module 14 Each of the light-emitting diodes 142, 144, and 146 emits light at a second color temperature. In the above embodiment, the first light-emitting module 12 and the second light-emitting module 14 have three light-emitting diodes, but the number of light-emitting diodes in each light-emitting module is not limited, and each light-emitting mode is not limited. The number of light-emitting diodes in the group may be equal or unequal.

When the main switch module SW1 is turned on, the inductor 16 stores energy. When the main switch module SW1 is not turned on, the inductor 16 releases energy and drives the sub-switch module SW2 to be turned on. Since the sub-switch module SW2 is connected in parallel to the first light-emitting module 12, when the sub-switch module SW2 is turned on, the two ends of the first light-emitting module 12 are short-circuited, so that the first light-emitting module 12 is turned on in the sub-switch module SW2. It does not shine. In the embodiment corresponding to FIG. 1A, the sub-switch module SW2 can be, for example, an N-type metal oxide semiconductor field effect transistor.

In other words, when the main switch module SW1 is turned on, the inductor 16 stores energy. At this time, the current I _L flows through the first current path P1 to cause the first light-emitting module 12 to emit light at the first color temperature. When the main switch module SW1 is not turned on, the inductor 16 releases the energy and drives the sub-switch module SW2 to be turned on. At this time, the current I _L flows through the second current path P2 to cause the second light-emitting module 14 to emit light at the second color temperature. And the first light emitting module 12 does not emit light. Thus, by controlling the main switch drive signal V _S module SW1 is turned on or not turned on, so that inductor 16 may be correspondingly further energy storage or energy release with a voltage V _L and the sub-drive switch module SW2 is turned on so that current flow I _L The first light emitting module 12 or the second light emitting module 14 emits light through the first current path P1 or the second current path P2.

Referring to FIG. 1B, FIG. 1C and FIG. 1D, FIG. 1B is a timing diagram of signals of a dimming circuit according to an embodiment of the present invention. FIG. 1C is a schematic diagram of a first current path of a dimming circuit according to an embodiment of the present invention. 1D is a schematic diagram of a second current path of a dimming circuit in an embodiment of the present invention. The relative timing of the control signal V _S , the voltage V _L and the current I _L is shown in FIG. 1B. The state of the control signal V _S corresponds to whether the main switch module SW1 is turned on or not. More specifically, when the control signal V _S is at a high level, the main switch module SW1 is turned on. When the control signal V _S is at a low level, the main switch module SW1 is not turned on.

Corresponding to each time point T1, T2, T3, and T4 in FIG. 1B, between time points T1 and T2 and between time points T3 and T4, the control signal V _{S is} at a high level and the main switch is made. The module SW1 is turned on. At this time, the inductor 16 stores energy, and the current I _L gradually becomes larger. The main switch module SW1 is turned on and the sub-switch module SW2 is not turned on. At this time, the current I _L flows through the first current path P1 to cause the first light-emitting module 12 to emit light at the first color temperature. The first current path P1 includes a first light emitting module 12, an inductor 16 and a main switch module SW1.

Between the time points T2 and T3, the control signal V _{S is} at a low level and the main switch module SW1 is not turned on. At this time, the inductor 16 is released, and the current I _{L is} gradually reduced. As described above, the sub-switch module SW2 is driven by the inductor 16 to be turned on. At this time, the current I _L flows through the second current path P2 to cause the second light-emitting module 14 to emit light at the second color temperature. The second current path P2 includes the second lighting module 14 , the inductor 16 and the sub-switch module SW2 .

As described above, the control signal V _{S is,} for example, a pulse width modulation signal, so that the length of the time interval between the respective time points T1, T2, T3, and T4 is actually adjustable. In other words, the control module 18 or the external device and the circuit adjust the time interval between the time points T1, T2, T3, and T4 to adjust the time at which the control signal V _S is occupied in a time period. The ratio further controls whether the main switch module SW1 and the sub-switch module SW2 are turned on or off. Therefore, the dimming circuit 1 can control the ratio of the illumination time of the first illumination module 12 and the second illumination module 14, and then mix the light of the first color temperature with the light of the second color temperature to output the light having the desired average color temperature. The average color temperature is in terms of the average color temperature perceived by the human eye over a period of time. In practice, the average color temperature of light that can be emitted by the dimming circuit 1 of the present invention is between the first color temperature and the second color temperature.

In one embodiment, the first color temperature is a warm color temperature and the second color temperature is a cold color temperature. When the dimming circuit 1 needs to emit light at a warmer color temperature, the time ratio of the high level in the high control signal V _S in each time period is increased, thereby lengthening the illumination time length of the first light emitting module 12, Light with a higher color temperature is mixed. Conversely, when the dimming circuit 1 needs to emit light at a cooler color temperature, the proportion of the time in which the high level in the low control signal V _S is occupied in each time period is adjusted, thereby lowering the illumination of the first light emitting module 12 The length of time to mix out light with a lower color temperature.

It should be noted that the above-mentioned voltage level, the correspondence between the switching module and the color temperature, and even the relative relationship between the time points T1 and T4 are known to those skilled in the art. It can be designed freely and is not limited here.

Please refer to FIG. 2 to explain the remaining implementations of the dimming circuit 1. FIG. 2 is a circuit diagram of the dimming circuit in another embodiment of the present invention. 2nd The difference between the embodiment disclosed in the figure and the embodiment disclosed in FIG. 1A lies in the connection position of the main switch module SW1 and the control module 18. In the embodiment corresponding to FIG. 1A, the main switch module SW1 is electrically connected to the low side of the dimming circuit 1. In the embodiment corresponding to FIG. 2, the main switch module SW1 is electrically connected to the high side of the dimming circuit 1. For detailed connection between components, please refer to the related description in Figure 1A, and the detailed description will not be repeated here.

Continuing the foregoing, in the embodiment corresponding to FIG. 2, when the main switch module SW1 is turned on, the current I _L flows through the first current path formed by the first light emitting module 12, the inductor 16 and the main switch module SW1, so that The first light emitting module 12 emits light at a first color temperature. When the main switch module SW1 is not turned on, the sub-switch module SW2 is turned on, so that the current I _L flows through the second current path formed by the second light-emitting module 14, the inductor 16 and the sub-switch module SW2, and the second current path is made. The light emitting module 14 emits light at a second color temperature. The related actions are similar to the embodiment disclosed in FIG. 1A and will not be described herein.

In the embodiment corresponding to FIG. 2, the main switch module SW1 may be a P-type metal oxide transistor (P-type metal), for example, an N-type metal oxide semiconductor field effect transistor. Oxide semiconductor field effect transistor, P-MOSFET/PMOS). At this time, the potential corresponding to the source is stable with respect to the potential of the drain. Therefore, when the main switch module SW1 is a P-type metal oxide semiconductor field effect transistor in the embodiment corresponding to FIG. 2, in addition to designing the voltage level of the control signal V _S , the uncertainty caused by voltage instability can be screened out. In addition to the factors, the chances of the dimming circuit 1 generating an error due to an unexpected voltage or current during operation are also reduced.

Please refer to FIG. 3 to explain the remaining implementations of the dimming circuit 1. FIG. 3 is a circuit diagram of the dimming circuit in a further embodiment of the present invention. The difference between the embodiment disclosed in FIG. 3 and the embodiment disclosed in FIG. 1A is the connection mode of the sub-switch module SW2 and the inductor 16, and the actuation mechanism of the dimming circuit 1 in the embodiment corresponding to FIG. 3 can be The foregoing and the like are not repeated here. In the embodiment corresponding to FIG. 3, the main switch module SW1 is located at the low end of the dimming circuit 1 and the inductor 16 is located at the high end of the dimming circuit 1.

When the main switch module SW1 is turned on, the current I _L flows through the first current path P1 formed by the first light emitting module 12, the inductor 16 and the main switch module SW1, so that the first light emitting module 12 emits light at the first color temperature. When the main switch module SW1 is not turned on, the sub-switch module SW2 is turned on, so that the current I _L flows through the second current path P2 formed by the second light-emitting module 14, the inductor 16 and the sub-switch module SW2, and The two light emitting modules 14 emit light at a second color temperature.

In this embodiment, the main switch module SW1 is an N-type metal oxide semiconductor field effect transistor as described above. In one embodiment, the sub-switch module SW2 is a P-type metal oxide semiconductor field effect device. Crystal. The considerations for applying the N-type or P-type metal oxide semiconductor field effect transistors to the main switch module SW1 and the sub-switch module SW2 are as described above, and are not described herein.

Please refer to FIG. 4 to explain the remaining implementations of the dimming circuit 1. FIG. 4 is a circuit diagram of the dimming circuit in still another embodiment of the present invention. The difference between the embodiment disclosed in FIG. 4 and the embodiment disclosed in FIG. 3 is the connection mode of the main switch module SW1, and the dimming circuit 1 in the embodiment corresponding to FIG. 4 The system can be deduced by the foregoing, and the details are not repeated here. In the embodiment corresponding to FIG. 4, the main switch module SW1 is located at the high end of the dimming circuit 1.

Similar to the previous embodiments, when the main switch module SW1 is turned on, the current I _L flows through the first current path formed by the first light emitting module 12, the inductor 16 and the main switch module SW1, so that the first light emitting module 12 emits light at a first color temperature. When the main switch module SW1 is not turned on, the sub-switch module SW2 is turned on, so that the current I _L flows through the second current path formed by the second light-emitting module 14, the inductor 16 and the sub-switch module SW2, and the second current path is made. The light emitting module 14 emits light at a second color temperature.

In this embodiment, the main switch module SW1 is an N-type metal oxide semiconductor field effect transistor as described above. In other embodiments, the sub-switch module SW2 is a P-type metal oxide semiconductor field effect device. Crystal.

Please refer to FIG. 5 to assist in explaining another embodiment of the present invention. FIG. 5 is a circuit diagram of a dimming circuit in still another embodiment of the present invention. The first light-emitting module 12 and the second light-emitting module 14 of the foregoing embodiments are connected in parallel with each other, and the inductor 16 is electrically connected between the two. The first light-emitting module 12 and the second light-emitting module 14 of the embodiment corresponding to the fifth embodiment are connected in series with each other, and the inductor 16 is connected in series between the two. In the embodiment corresponding to FIG. 5, the power source 2, the first light emitting module 12, the inductor 16 and the main switch module SW1 constitute a first current path P1. The power source 2, the sub-switch module SW2, the inductor 16 and the second lighting module 14 constitute a second current path P2.

Continuing the foregoing, the main switch module SW1 is selectively turned on according to the control signal V _S . When the main switch module SW1 is turned on, the current I _L flows through the first current path P1 formed by the first light emitting module 12, the inductor 16 and the main switch module SW1, so that the first light emitting module 12 emits light at the first color temperature. When the main switch module SW1 is not turned on, the sub-switch module SW2 is turned on, so that the current I _L flows through the second current path P2 formed by the second light-emitting module 14, the inductor 16 and the sub-switch module SW2, and The two light emitting modules 14 emit light at a second color temperature. In the embodiment corresponding to FIG. 5, the main switch module SW1 and the sub-switch module SW2 are both N-type metal oxide semiconductor field effect transistors.

In practice, the dimming circuit 1 of the present invention may include a protection unit or a voltage dividing unit to facilitate the operation of the circuit. The following is an example of another embodiment of the embodiment corresponding to FIG. 1A. Please refer to FIG. 6 for assistance in explanation. FIG. 6 is a circuit diagram showing another embodiment of the dimming circuit in FIG. 1A. As shown in FIG. 6, the dimming circuit 1 further has a first protection unit D1, D2, a second protection unit 148, a voltage dividing unit 17, and a detection resistor 160.

The first protection units D1 and D2 are respectively connected in parallel to the main switch module SW1 and the sub-switch module SW2. In more detail, the two ends of the first protection unit D1 are electrically connected to the first end N1 and the second end N2 of the main switch module SW1, respectively. The two ends of the second protection unit D2 are electrically connected to the first end N4 and the second end N5 of the sub-switch module SW2, respectively. The first protection units D1, D2 are used to protect the main switch module SW1 and the sub-switch module SW2 while reducing the voltage drop. The first protection units D1, D2 are, for example, diodes.

The second protection unit 148 is connected in series to the LEDs 142-146 and is used to receive a reverse bias to protect the second illumination module 14 from being excessively reversed. Pressure damage. The second protection unit 148 can be, for example, a Schottky Diode.

The voltage dividing unit 17 has a first resistor 172 and a second resistor 174, and the first resistor 172 is connected in series with the second resistor 174. In more detail, the voltage dividing unit 17 has a first end, a second end, and a voltage dividing end, wherein the first end and the second end are respectively one end of the first resistor 172 and the second resistor 174, and the voltage dividing end is A junction where the first resistor 172 and the second resistor 174 are connected to each other.

The first end and the second end of the voltage dividing unit 17 are electrically connected to the two ends of the inductor 16, respectively, and the voltage dividing end of the voltage dividing unit 17 is electrically connected to the control end N6 of the sub-switch module SW2. The voltage dividing unit 17 is configured to draw a potential difference of a proportion of the induced voltage of the inductor 16 to drive the sub-switch module SW2 when the inductor 16 is released. Thereby, excessive transient current is prevented from damaging the sub-switch module SW2. Generally, the resistance values of the first resistor 172 and the second resistor 174 are several thousand ohms or more. In order to reduce the power consumption of the voltage dividing unit 17, the higher the resistance value is within the allowable range, the better.

In practice, the detecting resistor 160 in FIG. 6 may be any circuit or function module capable of detecting current or voltage, and connected to the dimming circuit 1 in series or in parallel, where only the detecting resistor 160 is used. The example is not limited to this. As shown in the figure, the detecting resistor 160 has a first resistor terminal N13 and a second resistor terminal N14. The first resistor terminal N13 is electrically connected to the second inductor terminal N12 of the inductor 16. The second resistor terminal N14 is electrically connected to the first switch module. The first end N1 of the group SW1, the second resistor 174 of the voltage dividing unit 17, and the second input end N9 of the second lighting module 14. In addition, the first resistance end N13 and the second resistance end N14 of the detecting resistor 160 The control module 18 is electrically connected to each other.

Continuing the foregoing, when current I _L flows through inductor 16, current I _L also flows through sense resistor 160. At this time, the control module 18 receives the terminal voltage V _R across the detecting resistor 160 and controls the current flowing through the first lighting module 12 and the current of the second lighting module 14 to make the two currents the same size. . Therefore, the first light-emitting module 12 and the second light-emitting module 14 can be adjusted to have the same current and have the same brightness when emitting light at different color temperatures.

In summary, the present invention provides a dimming circuit, where the dimming circuit includes a first lighting module, a second lighting module, and a corresponding main switch module, a sub-switch module, and an inductor. The first lighting module, the inductor and the main switch module form a first current path, and the second lighting module, the inductor and the sub-switch module form a second current path. When the first current path is turned on, the first light emitting module emits light at a first color temperature. When the second current path is turned on, the first light emitting module emits light at the second color temperature. On the other hand, when the first current path is turned on, the second current path is not turned on. Conversely, when the second current path is turned on, the first current path is not turned on. Thereby, it is possible to control the time ratio of the first light-emitting module and the second light-emitting module to alternately emit light, thereby mixing the light having the desired color temperature.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

1‧‧‧ dimming circuit

12‧‧‧First lighting module

122, 124, 126‧‧‧Lighting diodes

14‧‧‧Second lighting module

142, 144, 146‧‧‧Lighting diodes

16‧‧‧Inductance

18‧‧‧Control Module

IL‧‧‧ current

N1, N4‧‧‧ first end

N2, N5‧‧‧ second end

N3, N6‧‧‧ control terminal

N7‧‧‧ first input

N8‧‧‧ first output

N9‧‧‧ second input

N10‧‧‧ second output

N11‧‧‧first inductor

N12‧‧‧second inductor

SW1‧‧‧ main switch module

SW2‧‧‧ sub-switch module

V _L ‧‧‧ voltage

V _S ‧‧‧ control signal

2‧‧‧Power supply

Claims (14)

A dimming circuit includes: a main switch module, selectively turning on a first current path according to a control signal; and a first light emitting module, the first light emitting mode when a current flows through the first current path The group emits light at a first color temperature; an inductor, when the current flows through the first current path, the inductor stores energy, and when the current does not flow through the first current path, the inductor releases energy; a sub-switch module, electricity Connecting the inductor, when the inductor is released, the sub-switch module is driven by the inductor to conduct a second current path; and a second lighting module is electrically connected to the sub-switch module when current flows through In the second current path, the second illumination module emits light at a second color temperature; wherein the first illumination module, the inductor and the main switch module belong to the first current path, and the second illumination mode The group, the inductor and the sub-switch module belong to the second current path. The dimming circuit of claim 1, wherein the first lighting module has a first input end and a first output end, and the second lighting module has a second input end and a second output end. The first input end is electrically connected to the second output end, one end of the inductor is electrically connected to the first output end, and the other end of the inductor is electrically connected to the second input end, the main switch module has a a first end, a second end and a control end, the first end is electrically connected to the second input end, the inductor The other end is connected to the sub-switch module, and the second end is electrically connected to a power connection port of the dimming circuit, and the control end is configured to receive the control signal. The dimming circuit of claim 1, wherein the first lighting module has a first input end and a first output end, and the second lighting module has a second input end and a second output end. The first input end is electrically connected to the second output end, one end of the inductor is electrically connected to the first output end, and the other end of the inductor is electrically connected to the second input end, the main switch module has a a first end, a second end, and a control end, the first end is electrically connected to a power connection port of the dimming circuit, and the second end is electrically connected to the first input end, the second output end, and the The sub-switch module is configured to receive the control signal. The dimming circuit of claim 1, wherein the first lighting module has a first input end and a first output end, and the second lighting module has a second input end and a second output end. The first output end is electrically connected to the second input end, one end of the inductor is electrically connected to the first input end, and the other end of the inductor is electrically connected to the second output end, the main switch module has a a first end, a second end and a control end, the first end is electrically connected to the first output end, the sub-switch module and the second input end, and the second end is electrically connected to the dimming circuit After a power connection, the control terminal is configured to receive the control signal. The dimming circuit of claim 1, wherein the first lighting module has a first input end and a first output end, and the second lighting module has a second input end and a second output end. The first output end is electrically connected to the second input end, and one end of the inductor is electrically connected to the first input end, and the other end of the inductor is Electrically connecting the second output end, the main switch module has a first end, a second end and a control end, the first end is electrically connected to a power connection port of the dimming circuit, the second end The other end of the inductor is electrically connected to the second output end, and the control end is configured to receive the control signal. The dimming circuit of claim 1, wherein the first lighting module has a first input end and a first output end, and the second lighting module has a second input end and a second output end. The first output end is electrically connected to the second input end, one end of the inductor is electrically connected to the second input end, and the other end of the inductor is electrically connected to the first output end, and the main switch module has a a first end, a second end and a control end, the first end is electrically connected to the second input end, the sub-switch module and the one end of the inductor, and the second end is electrically connected to the second output end After being connected to a power source of the dimming circuit, the control terminal is configured to receive the control signal. The dimming circuit of any one of claims 1 to 6, wherein the control signal is a Pulse Width Modulation (PWM). The dimming circuit of claim 1 to claim 6 further includes a control module electrically connected to the main switch module, and the control module is configured to generate the control signal. The dimming circuit of claim 2 or 6, wherein the main switch module is an N-type metal oxide semiconductor field effect transistor, and the sub-switch module is an N-type metal oxide semiconductor field effect transistor. The dimming circuit of claim 3, wherein the main switch module is an N-type or P-type metal oxide semiconductor field effect transistor, and the sub-switch module is an N-type metal oxide semiconductor field effect transistor . The dimming circuit according to claim 4 or 5, wherein the main switch module is an N-type or P-type metal oxide semiconductor field effect transistor, and the sub-switch module is a P-type metal oxide semiconductor field effect Transistor. The dimming circuit of claim 1, wherein the second lighting module comprises a plurality of light emitting diodes and a protection unit, and the protection unit is connected in series to the light emitting diodes. The dimming circuit of claim 1, further comprising a voltage dividing unit having a first end, a second end and a third end, the first end of the voltage dividing unit and the first end of the voltage dividing unit The two ends are electrically connected to the two ends of the inductor, and the third end of the voltage dividing unit is electrically connected to a control end of the sub-switch module. The dimming circuit of claim 8, further comprising a detecting unit electrically connected to the inductor and the control module, wherein the detecting unit is configured to indicate according to a current flowing through the inductor or a terminal voltage of the inductor The control module generates the control signal.