LED lamp brightness control circuit used in light and shadow test scene

Abstract

The invention provides an LED lamp brightness control circuit used in a light and shadow test scene, which comprises a control module, a digital-to-analog conversion module, a plurality of LED driving modules and a detection module which are mutually connected, and is characterized in that any LED driving module comprises a first driving unit and a second driving unit; the first driving unit comprises an operational amplifier U6A, a resistor R9, a resistor R44, a capacitor C17 and a switching tube Q4; the positive input end of the operational amplifier U6A is connected to the digital-to-analog conversion module, the negative input end of the operational amplifier U6A is grounded through a resistor R9, and the output end of the operational amplifier U6A is connected to the grid electrode of the switching tube Q4; the source electrode of the switching tube Q4 is connected between the negative input end of the operational amplifier U6A and the resistor R9, and the drain electrode of the switching tube Q4 is used for being connected with an LED lamp so as to control on and off of the LED lamp; the resistor R44 and the capacitor C17 are both connected between the output end of the operational amplifier U6A and the resistor R9.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and particularly to an LED lamp brightness control circuit for a light and shadow test scenario. Background Art

[0002] Due to their fast response speed, low energy consumption, and high luminous efficiency, LED lamps have been widely used in various precision control scenarios, such as brightness adjustment test platforms, light and shadow imaging devices, etc. In such applications, higher control precision and stability requirements are put forward for the on / off state and brightness change of the LED.

[0003] However, in practical applications, existing LED drive circuits often have problems with insufficient control precision. Especially when the LED needs to be kept in the off state, a small current may still be introduced due to factors such as circuit leakage, interference coupling, or device biasing, resulting in weak light emission or an uncertain state of the LED. This non-ideal "pseudo-off" state will interfere with the precision test environment or image acquisition system, affecting the accuracy of brightness grading and the recognition effect of image contrast. Therefore, how to stably maintain the off state of the LED while ensuring its brightness control ability and avoiding being lit by small currents has become a key technical problem in the current design of LED drive circuits. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the LED lamp in the prior art may still be interfered by small currents and cause false lighting when it is not lit.

[0005] The present invention provides an LED lamp brightness control circuit for a light and shadow test scenario, including a control module, a digital-to-analog conversion module, a plurality of LED drive modules, and a detection module that are connected to each other. Any one of the LED drive modules includes a first drive unit and a second drive unit. The first drive unit includes an operational amplifier U6A, a resistor R9, a resistor R44, a capacitor C17, and a switching transistor Q4;

[0006] The positive input terminal of the operational amplifier U6A is connected to the digital-to-analog conversion module, the negative input terminal is grounded through the resistor R9, and the output terminal is connected to the gate of the switching transistor Q4;

[0007] The source terminal of the switching transistor Q4 is connected between the negative input terminal of the operational amplifier U6A and the resistor R9, and the drain terminal of the switching transistor Q4 is used to connect to the LED lamp to control the conduction and cutoff of the LED lamp;

[0008] Both the resistor R44 and the capacitor C17 are connected between the output terminal of the operational amplifier U6A and the resistor R9.

[0009] Optionally, the first driving unit further includes a switching transistor Q2, whose gate is connected to the drain of the switching transistor Q4, the source of the switching transistor Q2 is grounded, and the drain of the switching transistor Q2 is connected to the detection module;

[0010] A resistor R7, whose first end is connected between the switching transistor Q4 and the resistor R9, and the second end is connected between the first end of the switching transistor Q2 and the resistor R9;

[0011] A capacitor C15, whose first end is connected to the second end of the switching transistor Q4, and the second end of the capacitor C15 is connected to an external power supply.

[0012] Optionally, the first driving unit further includes a switching transistor Q3, the drain of the switching transistor Q3 is connected to the gate of the switching transistor Q4, the source is grounded, and the gate is connected to the control module.

[0013] Optionally, the LED lamp brightness control circuit further includes a plurality of current mirror feedback modules;

[0014] Wherein, the input end of any one of the current mirror feedback modules is connected to the drain of the switching transistor Q2, and the output end is connected to the detection module, for transmitting a feedback current proportional to the drain current of Q2 to the detection module to judge the conduction state of Q4.

[0015] Optionally, any one of the current mirror feedback modules includes a transistor Q5 and a transistor Q7;

[0016] The collector of the transistor Q5 is connected to the drain of the switching transistor Q2, and the base is connected to the base of the transistor Q7;

[0017] The emitter of the transistor Q7 is grounded through a resistor R6, and the collector is connected to the detection module.

[0018] Optionally, the plurality of current mirror feedback modules have the same circuit structure, and each current mirror feedback module is connected to the LED driving module and the detection module.

[0019] Optionally, the second driving unit is connected to the first driving unit through a socket J5, and the second driving unit has the same circuit structure as the first driving unit.

[0020] Optionally, the plurality of LED driving modules have the same circuit structure, and the plurality of LED driving modules are all connected to the control module and the detection module.

[0021] Optionally, the LED lamp brightness control circuit further includes a power supply module, which is connected to the control module, the digital-to-analog conversion module, multiple LED driving modules, and the detection module to provide operating voltage for them.

[0022] Optionally, the control module is further configured to uniformly adjust the PWM duty cycle among the multiple LED driving modules, so that the brightness output by each LED lamp is kept consistent.

[0023] According to the solution of the present invention, by reasonably configuring the operational amplifier U6A, the resistor R9, the resistor R44, the capacitor C17, and the switching transistor Q4, a drive control loop with sensitive response and strong interference suppression ability is constructed. The operational amplifier U6A receives the brightness control signal from the digital-to-analog conversion module, and its output terminal forms an RC feedback network with the resistor R44 and the capacitor C17, which is used to stabilize the output voltage of U6A and suppress high-frequency noise interference. The resistor R9 is arranged between the negative input terminal of U6A and the ground to provide a fixed reference to ensure the stable operation of the operational amplifier. Q4 serves as a current control switch to control the on-off state of the LED according to the output of U6A. The above-mentioned devices work together to achieve fine control of the LED conduction current, and when there is no need for brightness output, the resistor R44 is used to quickly discharge the weak interference current, effectively preventing the phenomenon of abnormal micro-brightness or false triggering of the LED, and improving the control accuracy and reliability of the system in high-precision application scenarios such as light and shadow tests.

[0024] Furthermore, the auxiliary switching transistors Q2 and Q3 enhance the logic control of the main control switching transistor Q4, and through the connection between Q2 and the detection module, the accurate detection of the conduction state of Q4 is realized. The current mirror feedback module can transmit a feedback signal proportional to the drain current of Q2 to the detection module, providing a reliable closed-loop feedback for the control system and improving the stability and response accuracy of the overall operation. The structures of the current mirror feedback modules are the same, which is beneficial to maintaining the unity of detection accuracy. The second driving unit is connected to the first driving unit through the socket J5, supporting modular expansion and quick replacement. Multiple LED driving modules respectively control the corresponding LEDs based on a unified structure, and can flexibly adjust the brightness according to the requirements of different channels. At the same time, the control module outputs a unified PWM duty cycle to ensure the overall brightness consistency and optimize the visual coordination effect in the light and shadow test environment.

[0025] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following describes the preferred embodiments of the present invention in detail. Description of the Drawings

[0026] Figure 1 Shows a block diagram of the LED lamp brightness control circuit for a light and shadow test scenario according to an embodiment of the present invention;

[0027] Figure 2 Shows the circuit topology diagram of an LED driving module according to an embodiment of the present invention;

[0028] Figure 3 Shows the circuit topology diagram of any current mirror feedback module according to an embodiment of the present invention;

[0029] Figure 4 Shows the circuit topology diagram of a power supply module according to an embodiment of the present invention;

[0030] Figure 5 Shows the circuit topology diagram of the digital-to-analog conversion module 200 according to an embodiment of the present invention;

[0031] Figure 6 Shows the circuit topology diagram of the control module 100 according to an embodiment of the present invention;

[0032] Figure 7 Shows the circuit topology diagram of the detection module 400 according to an embodiment of the present invention. Detailed implementation manners

[0033] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application in conjunction with the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the sake of description, only parts related to the present application are shown in the drawings, rather than all the structures. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0034] The terms "including" and "having" and any variations thereof in the present application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products, or devices.

[0035] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0036] Figure 1The block diagram of the LED lamp brightness control circuit in the light and shadow test scenario according to an embodiment of the present invention is shown. As Figure 1 shown, the LED lamp brightness control circuit includes a control module 100, a digital-to-analog conversion module 200, multiple LED driving modules, and a detection module 400 that are interconnected. Among them, the digital-to-analog conversion module 200 is used to convert the analog signal (such as the brightness adjustment signal) output by the control module 100 into a digital signal for the multiple LED driving modules to process and adjust. The LED driving modules control the brightness of their respective LED lamps according to the received digital signal, while the detection module 400 monitors the working state of the LED lamps in real time and sends feedback information to the control module 100 to ensure the precise control and stable operation of the system.

[0037] Figure 2 The circuit topology diagram of the LED driving module according to an embodiment of the present invention is shown. As Figure 2 shown, the LED driving module includes a first driving unit and a second driving unit. The first driving unit includes an operational amplifier U6A, a resistor R9, a resistor R44, a capacitor C17, and a switching transistor Q4. The positive input terminal of the operational amplifier U6A is connected to the digital-to-analog conversion module 200, the negative input terminal is grounded through the resistor R9, and the output terminal is connected to the gate of the switching transistor Q4. The source terminal of the switching transistor Q4 is connected between the negative input terminal of the operational amplifier U6A and the resistor R9, and the drain terminal of the switching transistor Q4 is used to connect to the LED lamp to control the conduction and turn-off of the LED lamp. Both the resistor R44 and the capacitor C17 are connected between the output terminal of the operational amplifier U6A and the resistor R9.

[0038] In this embodiment, the operational amplifier U6A, resistor R9, resistor R44, capacitor C17, and switching transistor Q4 form a closed-loop drive control structure for precisely controlling the on / off state of the LED lamp. Among them, the operational amplifier U6A outputs a drive voltage according to the control voltage signal received at its positive input terminal, controls the gate potential of the switching transistor Q4, and realizes the conduction or cutoff of Q4 to control the lighting or extinguishing of the LED lamp. The negative input terminal of the operational amplifier U6A is grounded through the resistor R9 to form a basic negative feedback path, enhancing the response stability of the system. The resistor R44 and the capacitor C17 are commonly connected between the output terminal of U6A and R9 to form a resistor-capacitor compensation network, which not only stabilizes the change of the op-amp output, improves the dynamic response speed and anti-interference ability of the entire feedback loop, but also effectively discharges the tiny current caused by the bias current of the operational amplifier or external weak interference when the LED is not conducting or the control voltage is at a low level, preventing it from accumulating in the feedback loop and causing mis-triggering or offset problems. In particular, the source of Q4 is fed back to the negative input terminal of the op-amp to further construct a closed-loop path for current regulation. Cooperating with the above compensation network, it can suppress low-level drift while maintaining the high responsiveness of the system, thus achieving double guarantees for the driving accuracy and stability of the LED. The coordinated cooperation among the above components forms a stable and reliable dynamic regulation and control mechanism for the working state of the LED, which is applicable to application scenarios with high requirements for light source accuracy.

[0039] According to the above embodiment, by reasonably configuring the operational amplifier U6A, resistor R9, resistor R44, capacitor C17, and switching transistor Q4, a drive control loop with sensitive response and strong interference suppression ability is constructed. The operational amplifier U6A receives the brightness control signal from the digital-to-analog conversion module 200, and its output terminal forms an RC feedback network with the resistor R44 and the capacitor C17 to stabilize the output voltage of U6A and suppress high-frequency noise interference. The resistor R9 is provided between the negative input terminal of U6A and the ground to provide a fixed reference to ensure the stable operation of the op-amp. Q4 serves as a current control switch to control the on / off state of the LED according to the output of U6A. The above devices work together to achieve fine control of the LED conduction current, and when there is no brightness output requirement, the resistor R44 is used to quickly discharge the weak interference current, effectively preventing the abnormal micro-brightness or mis-triggering phenomenon of the LED, and improving the control accuracy and reliability of the system in high-precision application scenarios such as light and shadow tests.

[0040] In one embodiment, referring to Figure 2, the first driving unit further includes a switching transistor Q2, a resistor R7, and a capacitor C15. The gate of the switching transistor Q2 is connected to the drain of the switching transistor Q4, the source is grounded, and the drain is connected to the detection module 400. The first end of the resistor R7 is connected between the switching transistor Q4 and the resistor R9, and the second end is connected between the first end of the switching transistor Q2 and the resistor R9. The first end of the capacitor C15 is connected to the second end of the switching transistor Q4, and the second end of the capacitor C15 is connected to an external power supply.

[0041] In this embodiment, the switching transistor Q2 serves as a slave response device for the conduction state of Q4 and can be synchronously turned on when Q4 is turned on, thereby realizing the logical mapping of the operating state of the main control circuit and facilitating the detection module 400 to monitor the working state of the LED lamp in real time. Specifically, when the operational amplifier U6A outputs a high level, the switching transistor Q4 is turned on, and the voltage at its drain drops, resulting in insufficient gate-source voltage of the switching transistor Q2, and the switching transistor Q2 remains off, and the detection module 400 does not receive a signal; when the operational amplifier U6A outputs a low level, the switching transistor Q4 is turned off, and the voltage at its drain rises, increasing the gate-source voltage of the switching transistor Q2, and the switching transistor Q2 is driven to turn on, and its drain is pulled low, and the detection module 400 can receive the corresponding signal. Indirectly reflecting whether the switching transistor Q4 is turned off through the conduction state of the switching transistor Q2 helps the detection module 400 to determine in real time whether the LED lamp is in the off state.

[0042] In addition, the resistor R7 is used in cooperation with the switching transistor Q2 to play a role in current limiting and voltage division when the switching transistor Q2 is turned on, which can stabilize the detection signal and prevent false triggering caused by excessive current or voltage mutation. The capacitor C15 is used to buffer the voltage change at the drain node of the switching transistor Q4, reduce the interference caused by voltage fluctuation, and improve the stability of the control signal. The various devices in the present invention cooperate with each other, not only realizing the effective detection of the driving state, but also enhancing the stability and signal reliability of the entire control path during dynamic operation, which is beneficial to realizing the accurate monitoring and timely control of the LED driving state.

[0043] In one embodiment, the first driving unit further includes a switching transistor Q3. The drain of the switching transistor Q3 is connected to the gate of the switching transistor Q4, the source is grounded, and the gate is connected to the control module 100.

[0044] In some application scenarios, for example, when the LED light does not need to be lit, if there is a certain residual voltage on the gate of the switching transistor Q4, it may cause the switching transistor Q4 to not be fully turned off, resulting in a weak light of the LED light and affecting the test effect. To avoid such interference, the first driving unit is provided with a switching transistor Q3 for quickly pulling down the voltage of the gate of the switching transistor Q4. When the control module 100 outputs a high-level signal, the switching transistor Q3 conducts, and its source is grounded, which can quickly pull the gate voltage of the switching transistor Q4 to the ground potential, making the switching transistor Q4 reliably turned off and ensuring that the LED light is completely extinguished. This design improves the accuracy of the turn-off control, helps to avoid the mis-lighting of the LED, and ensures the accuracy and consistency of the light and shadow output.

[0045] The design of the switching transistor Q3 and the resistor R44 work together in this solution to jointly solve the influence on the LED brightness control when there is a small current leakage at the output terminal OUTA of the operational amplifier U6A. Specifically, the resistor R44 and the capacitor C17 form a resistor-capacitor compensation network, effectively stabilizing the output of the operational amplifier and avoiding false triggering or offset problems caused by the bias current of the operational amplifier or external weak interference. The switching transistor Q3, on the other hand, acts as a fast turn-off switch, which can quickly pull down the gate voltage when there is a residual gate voltage of the switching transistor Q4, ensuring that the switching transistor Q4 is completely turned off and avoiding unnecessary light of the LED light due to small current leakage. The combined effect of the two ensures the accuracy and stability of the LED driving system, avoids the interference caused by small current leakage, and guarantees the accuracy of the light and shadow test.

[0046] In one embodiment, the above-mentioned second driving unit is connected to the first driving unit through a socket J5, and the second driving unit has the same circuit structure as the first driving unit. Such a design is equivalent to a dual-channel driving module. In this configuration, a single LED driving module includes two interconnected driving units, which can drive two different loads (such as two LEDs or LEDs in different areas) simultaneously, thus improving the flexibility and expandability of the system. By adopting the same circuit structure, this design not only simplifies the hardware design and production but also enhances the reliability and consistency of the system, facilitating modular processing during debugging and maintenance.

[0047] In one embodiment, the above-mentioned multiple current mirror feedback modules have the same circuit structure, and each current mirror feedback module is connected to the LED driving module and the detection module 400.

[0048] To ensure the stability and flexibility of the system, the present invention further adopts a structural design of multiple drive modules in practical applications. Although a single LED drive module has achieved dual-channel independent control, in more complex application scenarios, such as light and shadow testing, in order to improve the electrical isolation, control accuracy, and flexibility of the spatial layout of the system, multiple LED drive modules are designed as independent modules. Each drive module is connected to the main control system through an independent interface, supporting parallel driving of multiple LEDs and fine-grained brightness regulation in different test environments. This design not only effectively improves the safety of the system (for example, preventing a single-module failure from affecting the entire system), but also enhances modularity, expandability, and adaptability, enabling quick configuration adjustment under the control requirements of LEDs with different specifications and quantities, thereby significantly improving the test accuracy and system stability.

[0049] In one embodiment, the LED lamp brightness control circuit of the present invention further includes a plurality of current mirror feedback modules. Among them, the input terminal of any one current mirror feedback module is connected to the drain of the switching transistor Q2, and the output terminal is connected to the detection module 400, for transmitting a feedback current proportional to the drain current of Q2 to the detection module 400 to judge the conduction state of Q4.

[0050] Figure 3 Shows the circuit topology diagram of any one current mirror feedback module according to an embodiment of the present invention. As Figure 3 shown, this current mirror feedback module includes transistor Q5 and transistor Q7. The collector of transistor Q5 is connected to the drain of switching transistor Q2, and the base is connected to the base of transistor Q7. The emitter of transistor Q7 is grounded through resistor R6, and the collector is connected to the detection module 400.

[0051] The current mirror feedback module of the present invention forms a current mirror structure through transistors Q5 and Q7, copies the drain current of switching transistor Q2 to the collector of Q7, and transmits this feedback current to the detection module 400 to judge the conduction state of Q4 in real time. This design can accurately feedback the drain current of Q2, improve the accuracy and reliability of the detection module 400, and ensure accurate monitoring of the conduction state. At the same time, the current mirror structure provides a fast response ability, ensuring that the system can make adjustments in a short time, especially suitable for applications such as light and shadow testing that require high precision and high responsiveness. In addition, this design simplifies the circuit structure and improves the integration and stability of the system.

[0052] In one embodiment, the LED lamp brightness control circuit of the present invention further includes a power supply module. Figure 4The circuit topology diagram of the power module according to an embodiment of the present invention is shown. The power module is connected to the control module 100, the digital-to-analog conversion module 200, multiple LED driving modules, and the detection module 400 to provide operating voltage for them. In one embodiment, the BD54FA1FP3 and LM78MXX chips are used for the power module.

[0053] According to the above embodiment of the present invention, the auxiliary switching transistors Q2 and Q3 enhance the logic control of the main control switching transistor Q4, and through the connection between Q2 and the detection module 400, the accurate detection of the conduction state of Q4 is realized. The current mirror feedback module can transmit the feedback signal proportional to the drain current of Q2 to the detection module 400, providing a reliable closed-loop feedback for the control system, improving the stability and response accuracy of the overall operation. The structures of the current mirror feedback modules are the same, which is beneficial to maintaining the unity of detection accuracy. The second driving unit is connected to the first driving unit through the socket J5, supporting modular expansion and quick replacement. Multiple LED driving modules respectively control the corresponding LEDs based on the unified structure, and can flexibly adjust the brightness according to the requirements of different channels. At the same time, the control module 100 unifies the PWM duty cycle output to ensure the overall brightness consistency and optimize the visual coordination effect in the light and shadow test environment.

[0054] Figure 5 The circuit topology diagram of the digital-to-analog conversion module 200 according to an embodiment of the present invention is shown. Refer to Figure 5 , in this embodiment, the ADR425 and DAC7578 chips are used for the digital-to-analog conversion module 200, where the ADR425 is used to provide an accurate reference voltage, and the DAC7578 is used to convert the analog control signal into the corresponding digital signal and output it to the LED driving module.

[0055] Figure 6 The circuit topology diagram of the control module 100 according to an embodiment of the present invention is shown. Refer to Figure 6 , in this embodiment, the Atmega32U4-AU chip is used for the control module 100.

[0056] In one embodiment, the control module 100 is further configured to uniformly adjust the PWM duty cycle among multiple LED driving modules, so that the brightness output by each LED lamp remains consistent. By uniformly adjusting the PWM duty cycle among multiple LED driving modules through the control module 100, it is possible to ensure that the brightness output by each LED lamp is highly consistent. This design is particularly important in application scenarios with extremely high requirements for brightness consistency, such as light and shadow tests, because it effectively eliminates the problem of uneven brightness caused by differences in control signals between driving modules, ensuring the accuracy and consistency of the light source. Further, uniformly adjusting the PWM duty cycle not only improves the control accuracy of the system, but also optimizes the coordination between driving modules, enhancing the stability of the system and the reliability of test results.

[0057] Figure 7 Fig. 4 shows the circuit topology diagram of the detection module 400 according to an embodiment of the present invention. Referring to Figure 7 , in this embodiment, the detection module 400 uses a PCA9555PW chip.

[0058] It should be specifically noted that although these specific chips are selected in this embodiment for the above modules, in other application scenarios, any other chips that can meet the system accuracy, stability, and function requirements can also be used as alternatives to achieve the same purpose and effect.

[0059] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0060] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An LED lamp brightness control circuit for a light and shadow test scenario, characterized in that, It includes a control module, a digital-to-analog conversion module, multiple LED driving modules and a detection module that are interconnected. Any one of the LED driving modules includes a first driving unit and a second driving unit. The first driving unit includes an operational amplifier U6A, a resistor R9, a resistor R44, a capacitor C17 and a switching transistor Q4; The positive input terminal of the operational amplifier U6A is connected to the digital-to-analog conversion module, the negative input terminal is grounded through the resistor R9, and the output terminal is connected to the gate of the switching transistor Q4; The source terminal of the switching transistor Q4 is connected between the negative input terminal of the operational amplifier U6A and the resistor R9, and the drain terminal of the switching transistor Q4 is used to connect to an LED lamp to control the conduction and turn-off of the LED lamp; Both the resistor R44 and the capacitor C17 are connected between the output terminal of the operational amplifier U6A and the resistor R9.

2. The LED lamp brightness control circuit according to claim 1, wherein The first driving unit further includes a switching transistor Q2, whose gate is connected to the drain of the switching transistor Q4, the source of the switching transistor Q2 is grounded, and the drain of the switching transistor Q2 is connected to the detection module; A resistor R7, whose first end is connected between the switching transistor Q4 and the resistor R9, and the second end is connected between the first end of the switching transistor Q2 and the resistor R9; A capacitor C15, whose first end is connected to the second end of the switching transistor Q4, and the second end of the capacitor C15 is connected to an external power supply.

3. The LED lamp brightness control circuit according to claim 2, wherein The first driving unit further includes a switching transistor Q3, the drain of the switching transistor Q3 is connected to the gate of the switching transistor Q4, the source is grounded, and the gate is connected to the control module.

4. The LED lamp brightness control circuit according to claim 3, wherein The LED lamp brightness control circuit further includes multiple current mirror feedback modules; Among them, the input terminal of any one of the current mirror feedback modules is connected to the drain of the switching transistor Q2, and the output terminal is connected to the detection module, which is used to transmit a feedback current proportional to the drain current of Q2 to the detection module to judge the conduction state of Q4.

5. The LED lamp brightness control circuit according to claim 4, characterized in that, Any one of the current mirror feedback modules includes a transistor Q5 and a transistor Q7; The collector of the transistor Q5 is connected to the drain of the switching transistor Q2, and the base is connected to the base of the transistor Q7; The emitter of the transistor Q7 is grounded through a resistor R6, and the collector is connected to the detection module.

6. The LED lamp brightness control circuit according to claim 5, wherein, The multiple current mirror feedback modules have the same circuit structure, and each current mirror feedback module is connected to the LED driving module and the detection module.

7. The LED lamp brightness control circuit according to claim 6, characterized in that, The second driving unit is connected to the first driving unit through a socket J5, and the second driving unit has the same circuit structure as the first driving unit.

8. The LED lamp brightness control circuit according to claim 7, wherein, The multiple LED driving modules have the same circuit structure, and the multiple LED driving modules are all connected to the control module and the detection module.

9. The LED lamp brightness control circuit according to claim 8, wherein, The LED lamp brightness control circuit further includes a power supply module, which is connected to the control module, the digital-to-analog conversion module, the multiple LED driving modules and the detection module to provide a working voltage for them.

10. The LED lamp brightness control circuit according to claim 9, wherein, The control module is further used to uniformly adjust the PWM duty cycle among the multiple LED driving modules so that the brightness output by each LED lamp is consistent.

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