Dimming circuit, PCB and hidden power supply

Abstract

The utility model discloses a dimming circuit, PCB board and hidden power supply, dimming circuit includes input processing unit, flyback unit, control unit and output processing unit, the input end of input processing unit is used for connecting external power supply device, the output end of input processing unit is connected with the input end of flyback unit, the output end of input processing unit is connected with the output end of flyback unit. The output end of the flyback unit is in induction connection with the input end of the output processing unit, and the output end of the output processing unit is used for being connected with a lighting lamp; the feedback end of the output processing unit is connected with the input end of the control unit, and the output end of the control unit is connected with the control end of the output processing unit; according to the dimming circuit, the output processing unit is matched with the control unit, the working state of the hidden power supply can be obtained in real time and dynamically adjusted, light attenuation compensation is achieved, efficient operation of the hidden power supply is ensured, the service life of the hidden power supply is prolonged, and the maintenance frequency and the maintenance cost are reduced.

Description

Technical Field

[0001] This utility model relates to the field of lighting circuit technology, and in particular to a dimming circuit, PCB board and concealed power supply. Background Technology

[0002] In the current field of lighting technology, there are several limitations in the design and function of luminaire power supplies. These limitations not only affect the overall performance of the luminaires but also reduce the user experience. Specifically, most dimming power supplies on the market currently lack effective light decay compensation mechanisms, causing the brightness of the luminaires to gradually decrease over long-term use, making it impossible to maintain a stable lighting effect. Furthermore, the lack of power status monitoring and fault diagnosis functions makes it difficult for users to promptly identify and resolve potential problems, which not only affects the reliability of the luminaires but also reduces maintenance efficiency.

[0003] It is evident that existing technologies still need improvement and enhancement. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a dimming circuit that, through the cooperation of the output processing unit and the control unit, can obtain the working status of the hidden power supply in real time and make dynamic adjustments to achieve light attenuation compensation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A dimming circuit includes an input processing unit, a flyback unit, a control unit, and an output processing unit. The input terminal of the input processing unit is used to connect to an external power supply device. The output terminal of the input processing unit is connected to the input terminal of the flyback unit. The output terminal of the flyback unit is inductively connected to the input terminal of the output processing unit. The output terminal of the output processing unit is used to connect to a lighting fixture. The feedback terminal of the output processing unit is connected to the input terminal of the control unit. The output terminal of the control unit is connected to the control terminal of the output processing unit.

[0007] The dimming circuit also includes a DIP switch unit, the power supply terminal of which is connected to the output processing unit, and the output terminal of which is connected to the input terminal of the control unit.

[0008] In the dimming circuit, the input processing unit includes a first filter section, a rectifier section, and a detection section. The input terminal of the first filter section is used to connect to an external power supply device. The output terminal of the first filter section is connected to the input terminal of the rectifier section and the input terminal of the detection section, respectively. The output terminal of the rectifier section is connected to the input terminal of the flyback unit, and the output terminal of the detection section is connected to the input terminal of the control unit.

[0009] In the dimming circuit, the flyback unit includes a second filter section, a transient start-up section, a constant voltage control section, the primary side of transformer T1, and a first control chip U1. The input terminal of the second filter section is connected to the output terminal of the input processing unit, and the output terminal of the second filter section is connected to the primary side of transformer T1. The second filter section is also connected to the input terminal of the transient start-up section, and the output terminal of the transient start-up section is connected to pins VCC and VIN of the first control chip U1. The pin OUT of the first control chip U1 is connected to the input terminal of the constant voltage control section, and the output terminal of the constant voltage control section is connected to the primary side of transformer T1. The primary side of transformer T1 is connected to the input terminal of the output processing unit.

[0010] In the dimming circuit, the flyback unit further includes a sampling section and a first step-down section. The input terminal of the first step-down section is connected to the VCC pin of the first control chip U1, and the output terminal of the first step-down section is connected to the ZCD pin of the first control chip U1. The input terminal of the sampling section is connected to the constant voltage control section, and the output terminal of the sampling section is connected to the CS pin of the first control chip U1.

[0011] In the dimming circuit, the output processing unit includes the secondary side of transformer T1, a third filter section, a warm light output section, and a cold light output section. The secondary side of transformer T1 is inductively connected to the primary side of transformer T1. The secondary side of transformer T1 is also connected to the input terminal of the third filter section. The output terminal of the third filter section is connected to the power supply terminals of the warm light output section and the cold light output section, respectively. The output terminals of the warm light output section and the cold light output section are respectively used to connect to lighting fixtures. The control terminals of the warm light output section and the cold light output section are respectively connected to the output terminal of the control unit. The feedback terminals of the warm light output section and the cold light output section are respectively connected to the input terminal of the control unit.

[0012] In the dimming circuit described above, the structure of the cold light output section is the same as that of the warm light output section. The warm light output section includes a second control chip U2, a constant current control group, an output group, and a feedback group. The VIN pin of the second control chip U2 is connected to the output terminal of the third filter section, and the DRV pin of the second control chip U2 is connected to the input terminal of the constant current control group. The output terminal of the constant current control group is connected to the input terminal of the output group and the input terminal of the feedback group, respectively. The output terminal of the output group is used to connect to the lighting fixture, and the output terminal of the feedback group is connected to the input terminal of the control unit. The DIM pin of the second control chip U2 is connected to the output terminal of the control unit.

[0013] In the dimming circuit, the output processing unit further includes a second step-down section, the input terminal of which is connected to the output terminal of the third filter section, and the output terminal of the second step-down section is used to output a 3.3V DC voltage.

[0014] This utility model also provides a PCB board, on which the dimming circuit described above is printed.

[0015] This utility model also provides a concealed power supply, which uses any of the dimming circuits described above for operation control.

[0016] Beneficial effects:

[0017] This invention provides a dimming circuit that, through the coordinated operation of the output processing unit and the control unit, can monitor the operating status of the concealed power supply in real time and make dynamic adjustments. This not only enables light attenuation compensation but also allows users to promptly identify and resolve potential problems that may arise during the operation of the concealed power supply, thereby ensuring its stability, reliability, and efficiency. Furthermore, it extends the service life of the concealed power supply and reduces the frequency and cost of maintenance. Attached Figure Description

[0018] Figure 1 A circuit block diagram of the dimming circuit provided by this utility model;

[0019] Figure 2 The circuit schematic diagram of the input processing unit provided by this utility model;

[0020] Figure 3 The circuit schematic diagram of the flyback unit provided by this utility model;

[0021] Figure 4 Circuit diagram of the third filter section and the detection section provided by this utility model;

[0022] Figure 5 Circuit diagram of the cold light output section provided by this utility model;

[0023] Figure 6 The circuit diagram of the warm light output section provided by this utility model;

[0024] Figure 7 The circuit diagram of the control unit and DIP switch unit provided by this utility model.

[0025] Explanation of key component symbols: 1-Input processing unit, 11-First filter section, 12-Rectifier section, 13-Detection section, 2-Flyback unit, 21-Second filter section, 22-Transient start-up section, 23-Constant voltage control section, 24-Sampling section, 25-First step-down section, 3-Control unit, 4-Output processing unit, 41-Third filter section, 42-Warm light output section, 43-Cold light output section, 44-Second step-down section, 5-DIP switch unit. Detailed Implementation

[0026] This utility model provides a dimming circuit, a PCB board, and a concealed power supply. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and embodiments.

[0027] In the description of this utility model, it should be understood that the terms "installation" and "connection" should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] Please see Figures 1 to 7 This utility model provides a dimming circuit, including an input processing unit 1, a flyback unit 2, a control unit 3, and an output processing unit 4. The input terminal of the input processing unit 1 is used to connect to an external power supply device, and the output terminal of the input processing unit 1 is connected to the input terminal of the flyback unit 2. The output terminal of the flyback unit 2 is inductively connected to the input terminal of the output processing unit 4, and the output terminal of the output processing unit 4 is used to connect to a lighting fixture. The feedback terminal of the output processing unit 4 is connected to the input terminal of the control unit 3, and the output terminal of the control unit 3 is connected to the control terminal of the output processing unit 4.

[0029] This application discloses a dimming circuit that, through the coordinated operation of the output processing unit 4 and the control unit 3, can monitor the operating status of the hidden power supply in real time and make dynamic adjustments. This not only enables light attenuation compensation but also allows users to promptly identify and resolve potential problems that may occur during the operation of the hidden power supply, thereby ensuring its stability, reliability, and efficiency. Furthermore, it extends the service life of the hidden power supply and reduces the frequency and cost of maintenance.

[0030] In this embodiment, please refer to Figure 7 The control unit 3 is an MCU module, which is composed of a BP5016 chip and its peripheral circuits combined with a CS32F031K8U6 chip and its peripheral circuits.

[0031] Further, please refer to Figure 1 and Figure 7The dimming circuit also includes a DIP switch unit 5, the power supply terminal of which is connected to the output processing unit 4, and the output terminal of which is connected to the input terminal of the control unit 3.

[0032] In this embodiment, the DIP switch unit 5 includes a four-position DIP switch SW1. Pins 5, 6, 7, and 8 of the DIP switch SW1 are respectively connected to the output terminal of the second step-down unit 44. Pins 1 and 2 of the DIP switch SW1 are respectively connected to pin K2 of the MCU module, and pins 3 and 4 of the DIP switch SW1 are respectively connected to pin K1 of the MCU module. By setting the four-position DIP switch SW1, a variety of setting options are provided to meet different configuration requirements. This not only increases the flexibility of the concealed power supply during operation but also allows users to personalize the output current according to specific application scenarios, thereby ensuring that the lighting effect of the lighting fixture meets the user's needs.

[0033] Further, please refer to Figure 1 and Figure 2 The input processing unit 1 includes a first filter section 11, a rectifier section 12, and a detection section 13. The input terminal of the first filter section 11 is used to connect to an external power supply device. The output terminal of the first filter section 11 is connected to the input terminal of the rectifier section 12 and the input terminal of the detection section 13, respectively. The output terminal of the rectifier section 12 is connected to the input terminal of the flyback unit 2, and the output terminal of the detection section 13 is connected to the input terminal of the control unit 3.

[0034] In this embodiment, please refer to Figure 2The first filtering section 11 includes a first excitation coil LF1, a second excitation coil LF2, and a third excitation coil LF3. The rectifier section 12 includes a rectifier bridge BR1. The detection section 13 includes a seventh diode D7, an eighth diode D8, a second transistor Q2, and an optocoupler U5. One end of the first excitation coil LF1 is used to connect to an external power supply device, which can be AC ​​mains power. The other end of the first excitation coil LF1 is connected to the input terminal of the rectifier bridge BR1, the positive terminal of the seventh diode D7, and the positive terminal of the eighth diode D8 through the second excitation coil LF2 and the third excitation coil LF3, respectively. The rectifier bridge BR1... The output terminal is connected to the input terminal of the second filter section 21; the negative terminals of the seventh diode D7 and the eighth diode D8 are respectively connected to the base of the second transistor Q2, the collector of the second transistor Q2 is connected to one end of the emitter of the optocoupler U5, the other end of the emitter of the optocoupler U5 is connected to the VCC pin of the first control chip U1, and the emitter of the second transistor Q2 is grounded; the emitter of the optocoupler U5 is inductively connected to the receiver of the optocoupler U5, one end of the receiver of the optocoupler U5 is connected to the output terminal of the second step-down section 44, and the other end of the receiver of the optocoupler U5 is connected to the MS pin of the MUC module.

[0035] In this embodiment, the first filter section 11 consists of a first excitation coil LF1, a second excitation coil LF2, and a third excitation coil LF3, ensuring the purity and stability of the input power. The rectifier section 12 uses a rectifier bridge BR1 to convert AC power into DC power, providing a stable power supply for subsequent circuits. The detection section 13 consists of a seventh diode D7, an eighth diode D8, a second transistor Q2, and an optocoupler U5. The detection section 13 accurately monitors the state of the input circuit and feeds it back to the control unit 3, enabling the control unit 3 to dynamically adjust the operating state of the circuit and ensure that the circuit operates within a safe range.

[0036] Further, please refer to Figure 1 and Figure 3The flyback unit 2 includes a second filter section 21, a transient start-up section 22, a constant voltage control section 23, the primary side of transformer T1, and a first control chip U1. The input terminal of the second filter section 21 is connected to the output terminal of the input processing unit 1, and the output terminal of the second filter section 21 is connected to the primary side of transformer T1. The second filter section 21 is also connected to the input terminal of the transient start-up section 22. The output terminal of the transient start-up section 22 is connected to the VCC and VIN pins of the first control chip U1, respectively. The OUT pin of the first control chip U1 is connected to the input terminal of the constant voltage control section 23, and the output terminal of the constant voltage control section 23 is connected to the primary side of transformer T1. The primary side of transformer T1 is connected to the input terminal of the output processing unit 4.

[0037] In this embodiment, please refer to Figure 3 The first control chip U1 is model XP3359. The second filter section 21 includes a first inductor L1, a first capacitor CB1, a second capacitor CB2, a fifth resistor R5, a fifth capacitor C5, and a third diode D3. The transient startup section 22 includes a third field-effect transistor Q3 and a tenth diode D10. The constant voltage control section 23 includes a sixth diode D6 and a first field-effect transistor Q1. One end of the first inductor L1, one end of the first capacitor CB1, and one end of the second capacitor CB2 are respectively connected to the output terminal of the rectifier bridge BR. The other ends of the first capacitor CB1 and the second capacitor CB2 are respectively grounded. The other end of the first inductor L1 is respectively connected to one end of the fifth resistor R5, one end of the fifth capacitor C5, and a pin on the primary side of the transformer T1. 5. The gate and drain of the third field-effect transistor Q3 are connected to the VIN pin of the first control chip U1. The other end of the fifth resistor R5 and the other end of the fifth capacitor C5 are connected to the negative terminal of the third diode D3. The positive terminal of the third diode D3 is connected to the pin 3 of the primary side of the transformer T1. The drain of the third field-effect transistor Q3 is connected to the VCC pin of the first control chip U1 through the tenth diode D10. The OUT pin of the first control chip U1 is connected to the negative terminal of the sixth diode D6. The positive terminal of the sixth diode D6 is connected to the gate of the first field-effect transistor Q1. The drain of the first field-effect transistor Q1 is connected to the pin 3 of the primary side of the transformer T1. The source of the first field-effect transistor Q1 is connected to the pin CS of the first control chip U1.

[0038] In this embodiment, the XP3359 control chip is used to achieve efficient energy conversion, reduce energy loss, and improve the overall circuit efficiency through precise control algorithms. The constant voltage control unit 23, using a combination of the sixth diode D6 and the first field-effect transistor Q1, ensures stable output voltage, maintaining a constant output voltage even with input voltage fluctuations. The transient startup unit 22, including the third field-effect transistor Q3 and the tenth diode D10, can quickly respond to changes in input voltage to achieve rapid startup of the flyback unit 2, ensuring circuit stability under transient load changes. The source current of the first field-effect transistor Q1 is monitored via pin CS of the first control chip U1. When the current exceeds a set value, the chip automatically adjusts the control strategy to achieve overcurrent protection and prevent circuit damage. The second filter unit 21, including the first inductor L1, the first capacitor CB1, the second capacitor CB2, the fifth resistor R5, the fifth capacitor C5, and the third diode D3, effectively filters out high-frequency noise and interference in the input voltage, improving the purity of the output voltage.

[0039] Further, please refer to Figure 1 and Figure 3 The flyback unit 2 further includes a sampling unit 24 and a first buck unit 25. The input terminal of the first buck unit 25 is connected to the VCC pin of the first control chip U1, and the output terminal of the first buck unit 25 is connected to the ZCD pin of the first control chip U1. The input terminal of the sampling unit 24 is connected to the constant voltage control unit 23, and the output terminal of the sampling unit 24 is connected to the CS pin of the first control chip U1.

[0040] In this embodiment, the sampling unit 24 includes a thirty-fifth resistor R35 and a sixth capacitor C6. The first step-down unit 25 includes the auxiliary side of transformer T1, a fifth diode D5, a twenty-eighth capacitor C28, and a sixteenth resistor R16. One end of the thirty-fifth resistor R35 is connected to the source of the first field-effect transistor Q1, and the other end of the thirty-fifth resistor R35 and one end of the sixth capacitor C6 are respectively connected to pin CS of the first control chip U1. The other end of the sixth capacitor C6 is grounded. The auxiliary side of transformer T1 is inductively connected to the primary side of transformer T1, and one end of the auxiliary side of transformer T1 is respectively connected to pin CS of the first control chip U1. The pin ZCD, the positive terminal of the fifth diode D5, and one end of the twenty-eighth capacitor C28 are connected, and the other end of the auxiliary side of the transformer T1 is grounded; the negative terminal of the fifth diode D5 and the other end of the twenty-eighth capacitor C28 are respectively connected to one end of the sixteenth resistor R16, and the other end of the sixteenth resistor R16 is connected to the pin VCC of the first control chip U1; the first step-down section 25 achieves efficient voltage conversion and energy transfer through the inductive connection between the auxiliary side and the primary side of the transformer T1, and the synergistic effect of the fifth diode D5, the twenty-eighth capacitor C28, and the sixteenth resistor R16, thereby reducing energy loss and improving the overall efficiency of the circuit.

[0041] Further, please refer to Figure 1 and Figures 4 to 6 The output processing unit 4 includes a secondary side of transformer T1, a third filter 41, a warm light output 42, and a cold light output 43. The secondary side of transformer T1 is inductively connected to the primary side of transformer T1. The secondary side of transformer T1 is also connected to the input terminal of the third filter 41. The output terminal of the third filter 41 is connected to the power supply terminals of the warm light output 42 and the cold light output 43, respectively. The output terminals of the warm light output 42 and the cold light output 43 are respectively used to connect to lighting fixtures. The control terminals of the warm light output 42 and the cold light output 43 are respectively connected to the output terminal of the control unit 3. The feedback terminals of the warm light output 42 and the cold light output 43 are respectively connected to the input terminal of the control unit 3.

[0042] Further, please refer to Figures 4 to 6The structure of the cold light output unit 43 is the same as that of the warm light output unit 42. The warm light output unit 42 includes a second control chip U2, a constant current control group, an output group, and a feedback group. The VIN pin of the second control chip U2 is connected to the output terminal of the third filter unit 41. The DRV pin of the second control chip U2 is connected to the input terminal of the constant current control group. The output terminal of the constant current control group is connected to the input terminal of the output group and the input terminal of the feedback group, respectively. The output terminal of the output group is used to connect to the lighting fixture. The output terminal of the feedback group is connected to the input terminal of the control unit 3. The DIM pin of the second control chip U2 is connected to the output terminal of the control unit 3.

[0043] In this embodiment, please refer to Figure 5 and Figure 6 The second control chip U2 is model OC5031B. The constant current control group includes a fifth field-effect transistor Q5, a third inductor L3, a fifth filter capacitor EC5, a seventh capacitor C7, a fourth diode D4, and a resistor group consisting of multiple resistors connected in parallel. The output group includes a sixth excitation coil LF6 and a second connector OUT2. The feedback group includes a sixty-fourth resistor R64, a sixty-fifth resistor R65, and a sixty-third resistor R63. The DRV pin of the second control chip U2 is connected to the gate of the fifth field-effect transistor Q5. The drain of the fifth field-effect transistor Q5 is connected to one end of the third inductor L3. The other end of the third inductor L3 is connected to the negative terminal of the fifth capacitor EC5, the CS pin of the second control chip U2, one end of the sixty-third resistor R63, and one end of the fifth excitation coil LF5. The positive terminal of the fifth capacitor EC5... The third inductor L3 is connected to one end of the fifth excitation coil LF5 and one end of the resistor group, respectively; the other end of the third inductor L3 is connected to one end of the seventh capacitor C7 and the positive terminal of the fourth diode D4, respectively, and the other end of the seventh capacitor C7 and the negative terminal of the fourth diode D4 are connected to the other end of the resistor group, respectively; the other end of the sixth excitation coil LF6 is connected to the second connector OUT2, which is used to connect lighting fixtures; the other end of the sixty-third resistor R63 is connected to one end of the sixty-fourth resistor R64 and one end of the sixty-fifth resistor R65, respectively, and the other end of the sixty-fifth resistor R65 is grounded; the other end of the sixty-fourth resistor R64 is connected to the AD2 pin of the MCU module; and the DIM pin of the third control chip U3 is connected to the PWM2 pin of the MCU module.

[0044] In this embodiment, constant current control of the circuit is achieved through the cooperation of the second control chip U2 with components such as the fifth field-effect transistor Q5, the third inductor L3, and the fifth filter capacitor EC5, ensuring current stability and improving circuit efficiency. The feedback group, through the combination of the sixty-third resistor R63, the sixty-fourth resistor R64, and the sixty-fifth resistor R65, feeds back the circuit's operating status to the MCU module in real time, enabling the system to make precise adjustments based on the feedback signal, thus enhancing the circuit's flexibility and stability. The output group includes the sixth excitation coil LF6 and the second connector OUT2, facilitating connection to various lighting fixtures and improving the circuit's versatility and practicality. The third control chip U3's pin DIM is connected to the MCU module's pin PWM2, ensuring good compatibility with other control chips and MCU modules, facilitating system integration and expansion.

[0045] Further, please refer to Figure 1 and Figure 4 The output processing unit 4 further includes a second step-down unit 44, the input terminal of which is connected to the output terminal of the third filter unit 41, and the output terminal of the second step-down unit 44 is used to output a 3.3V DC voltage.

[0046] In this embodiment, the third filtering section 41 includes a first diode D1 and multiple filter capacitors, and the second step-down section 44 includes a fourth control chip U4, the fourth control chip U4 being a BP8501; the anode of the first diode D1 is connected to the secondary side of the transformer T1, the cathode of the first diode D1 is connected to the anode of the multiple filter capacitors, and the cathodes of the multiple filter capacitors are grounded; the anodes of the multiple filter capacitors are also connected to pin DR of the fourth control chip U4, and pin OUT of the fourth control chip U4 outputs a 3.3V DC voltage; by using the first diode D1 and multiple filter capacitors to form... The third filter section 41 effectively filters the voltage output from the secondary side of transformer T1, reducing voltage fluctuations and noise, and improving the stability of the output voltage. The fourth control chip U4, model BP8501, is used as the core component of the second step-down section 44. It boasts high performance, high reliability, and low power consumption, meeting the needs of various complex application scenarios. Connecting the positive terminals of multiple filter capacitors to the DR pin of the fourth control chip U4 further smooths the input voltage, ensuring the stable operation of the fourth control chip U4. The OUT pin of the fourth control chip U4 can output a stable 3.3V DC voltage, providing reliable power support for subsequent circuits.

[0047] This utility model also provides a PCB board, on which the dimming circuit described above is printed.

[0048] This utility model also provides a concealed power supply, which uses any of the dimming circuits described above for operation control.

[0049] It is understood that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of this utility model, and all such substitutions or changes should fall within the protection scope of this utility model.

Claims

1. A dimming circuit, characterized in that, The system includes an input processing unit, a flyback unit, a control unit, and an output processing unit. The input terminal of the input processing unit is used to connect to an external power supply device. The output terminal of the input processing unit is connected to the input terminal of the flyback unit. The output terminal of the flyback unit is inductively connected to the input terminal of the output processing unit. The output terminal of the output processing unit is used to connect to a lighting fixture. The feedback terminal of the output processing unit is connected to the input terminal of the control unit. The output terminal of the control unit is connected to the control terminal of the output processing unit.

2. The dimming circuit according to claim 1, characterized in that, It also includes a DIP switch unit, the power supply terminal of which is connected to the output processing unit, and the output terminal of which is connected to the input terminal of the control unit.

3. The dimming circuit according to claim 1, characterized in that, The input processing unit includes a first filter section, a rectifier section, and a detection section. The input terminal of the first filter section is used to connect to an external power supply device. The output terminal of the first filter section is connected to the input terminal of the rectifier section and the input terminal of the detection section, respectively. The output terminal of the rectifier section is connected to the input terminal of the flyback unit, and the output terminal of the detection section is connected to the input terminal of the control unit.

4. A dimming circuit according to claim 1, characterized in that, The flyback unit includes a second filter section, a transient start-up section, a constant voltage control section, the primary side of transformer T1, and a first control chip U1. The input terminal of the second filter section is connected to the output terminal of the input processing unit, and the output terminal of the second filter section is connected to the primary side of transformer T1. The second filter section is also connected to the input terminal of the transient start-up section. The output terminal of the transient start-up section is connected to pins VCC and VIN of the first control chip U1, respectively. The pin OUT of the first control chip U1 is connected to the input terminal of the constant voltage control section, and the output terminal of the constant voltage control section is connected to the primary side of transformer T1. The primary side of transformer T1 is connected to the input terminal of the output processing unit.

5. A dimming circuit according to claim 4, characterized in that, The flyback unit further includes a sampling section and a first buck section. The input terminal of the first buck section is connected to the VCC pin of the first control chip U1, and the output terminal of the first buck section is connected to the ZCD pin of the first control chip U1. The input terminal of the sampling section is connected to the constant voltage control section, and the output terminal of the sampling section is connected to the CS pin of the first control chip U1.

6. A dimming circuit according to claim 4, characterized in that, The output processing unit includes a secondary side of transformer T1, a third filter section, a warm light output section, and a cold light output section. The secondary side of transformer T1 is inductively connected to the primary side of transformer T1. The secondary side of transformer T1 is also connected to the input terminal of the third filter section. The output terminal of the third filter section is connected to the power supply terminals of the warm light output section and the cold light output section, respectively. The output terminals of the warm light output section and the cold light output section are respectively used to connect to lighting fixtures. The control terminals of the warm light output section and the cold light output section are respectively connected to the output terminal of the control unit. The feedback terminals of the warm light output section and the cold light output section are respectively connected to the input terminal of the control unit.

7. A dimming circuit according to claim 6, characterized in that, The structure of the cold light output section is the same as that of the warm light output section. The warm light output section includes a second control chip U2, a constant current control group, an output group, and a feedback group. The VIN pin of the second control chip U2 is connected to the output terminal of the third filter section. The DRV pin of the second control chip U2 is connected to the input terminal of the constant current control group. The output terminal of the constant current control group is connected to the input terminal of the output group and the input terminal of the feedback group, respectively. The output terminal of the output group is used to connect to the lighting fixture. The output terminal of the feedback group is connected to the input terminal of the control unit. The DIM pin of the second control chip U2 is connected to the output terminal of the control unit.

8. A dimming circuit according to claim 6, characterized in that, The output processing unit further includes a second step-down section, the input terminal of which is connected to the output terminal of the third filter section, and the output terminal of the second step-down section is used to output a 3.3V DC voltage.

9. A PCB board, characterized in that, The PCB board is printed with a dimming circuit as described in any one of claims 1-8.

10. A concealed power supply, characterized in that, The concealed power supply uses a dimming circuit as described in any one of claims 1-8 to achieve operation control.

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