Light source dimming control circuit and system

Abstract

The application provides a light source dimming control circuit and system, relates to the technical field of LED, and the circuit comprises a master control module, an analog dimming module and a PWM dimming module.When the master control module receives a large-current output instruction of an LED lamp, the master control module controls the PWM dimming module to be turned on and sends a first PWM signal to the analog dimming module, so that the analog dimming module outputs a first driving current flowing to the LED lamp.When the master control module receives a small-current output instruction of the LED lamp, the master control module sends a second PWM signal to the analog dimming module, so that the analog dimming module outputs a reference current; the master control module sends a third PWM signal to the PWM dimming module, so that the PWM dimming module is controlled to be turned on and turned off, thereby adjusting a second driving current flowing to the LED lamp on the basis of the reference current.The light source dimming control circuit can accurately dim the light source in a wide current range.

Description

Technical Field

[0001] This application relates to the field of LED technology, and more specifically, to a light source dimming control circuit and system. Background Technology

[0002] In a five-color cold light source system, the driving current required for each color LED chip is relatively wide, ranging from tens of milliamps to tens of amps. In order to accurately control the brightness of LED chips, existing dimming methods use analog dimming or PWM dimming.

[0003] In analog dimming mode, due to the leakage current inherent in the LED driver chip, even when the analog control voltage is set to 0, a non-negligible minimum current will still exist at its output. If this minimum current is still greater than the minimum operating current required by the LED chip, the actual current will be too high, thus affecting the accuracy of its spectral parameters. In PWM dimming mode, to avoid flicker perceptible to the human eye, the PWM dimming frequency is usually higher. However, an excessively high switching frequency will slow down the rise of the LED driver chip's output current from 0 to the maximum current range, making it unable to quickly follow the PWM signal changes. This results in the current varying within the non-linear range of duty cycle adjustment, making it impossible to accurately regulate the output current.

[0004] In summary, how to accurately dim a light source over a wide current range is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this application is to provide a light source dimming control circuit and system for accurately dimming a light source over a wide current range.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: On the one hand, this application provides a light source dimming control circuit, including: a main control module, an analog dimming module, and a PWM dimming module; The main control module is connected to the analog dimming module and the PWM dimming module respectively, and both the analog dimming module and the PWM dimming module are connected to the LED light; When the main control module receives a command to output a large current from the LED lamp, the main control module controls the PWM dimming module to turn on and sends a first PWM signal to the analog dimming module. The analog dimming module outputs a first driving current to the LED lamp according to the first PWM signal. When the main control module receives a command to output a small current from the LED, the main control module sends a second PWM signal to the analog dimming module, and the analog dimming module outputs a reference current based on the second PWM signal. The main control module also sends a third PWM signal to the PWM dimming module, and the PWM dimming module turns on and off according to the third PWM signal to adjust the second driving current flowing to the LED based on the reference current. Wherein, 0 ≤ second driving current ≤ reference current < first driving current.

[0007] Furthermore, the analog dimming module includes: a digital-to-analog converter and a drive unit; The digital-to-analog converter is connected to the main control module and the drive unit respectively, and the drive unit is also connected to the LED light; The digital-to-analog converter is used to convert the PWM signal sent by the main control module into an analog voltage, and send the analog voltage to the drive unit; The driving unit is used to output the first driving current or the reference current to the LED lamp according to the analog voltage.

[0008] Furthermore, the driving unit includes a current driver and a BUCK step-down circuit; the PWM dimming module includes a first switching transistor; The input terminal of the current driver is connected to the output terminal of the digital-to-analog converter, the output terminal of the current driver is connected to the control terminal of the BUCK buck circuit, the input terminal of the BUCK buck circuit is connected to the reference power supply, and the output terminal of the BUCK buck circuit is connected to the anode of the LED lamp; the cathode of the LED lamp is connected to the first terminal of the first switching transistor, the second terminal of the first switching transistor is grounded, and the control terminal of the first switching transistor is connected to the main control module. The current driver is used to output a drive PWM signal to the BUCK buck circuit according to the analog voltage; The BUCK step-down circuit is used to step down the reference voltage according to the drive PWM signal.

[0009] Furthermore, the driving PWM signal includes: a first driving PWM signal and a second driving PWM signal; The BUCK step-down circuit includes: a second switching transistor, a third switching transistor, and an inductor; The control terminals of the second and third switching transistors are respectively connected to the first and second output terminals of the current driver. The first terminal of the second switching transistor is connected to the reference power supply. The second terminal of the second switching transistor is connected to one end of the inductor and the first terminal of the third switching transistor. The second terminal of the third switching transistor is grounded. The other end of the inductor is connected to the anode of the LED. The current driver is used to output the first driving PWM signal and the second driving PWM signal to the control terminals of the second switch and the third switch respectively according to the analog voltage; wherein the duty cycle of the first driving PWM signal and the duty cycle of the second driving PWM signal are complementary.

[0010] Furthermore, the driving unit also includes a current sensing resistor; one end of the current sensing resistor is connected to the inductor, the other end of the current sensing resistor is connected to the anode of the LED, and the current driver is connected to both ends of the current sensing resistor; The current driver is used to adjust the duty cycle of the first driving PWM signal according to the voltage difference across the current sensing resistor until the voltage difference across the current sensing resistor is equal to the analog voltage.

[0011] Furthermore, the current driver and the two ends of the current sensing resistor are connected using a Kelvin four-wire system.

[0012] Furthermore, the driving unit also includes a first capacitor and a second capacitor; the first capacitor is connected in parallel across the two ends of the current sensing resistor, one end of the second capacitor is connected to one end of the current sensing resistor and the anode of the LED, and the other end of the second capacitor is grounded.

[0013] Furthermore, the first switch, the second switch, and the third switch are all NMOS transistors.

[0014] Furthermore, the light source dimming control circuit also includes a temperature detection resistor; The temperature sensing resistor is located close to the LED light, and both ends of the temperature sensing resistor are connected to the main control module.

[0015] On the other hand, this application also provides a light source dimming control system, which includes a light source dimming control circuit as described in any of the foregoing embodiments.

[0016] Compared with the prior art, this application has the following advantages: This application provides a light source dimming control circuit and system. The circuit includes a main control module, an analog dimming module, and a PWM dimming module. The main control module is connected to both the analog dimming module and the PWM dimming module, and both are connected to an LED lamp. When the main control module receives a command from the LED lamp to output a large current, it controls the PWM dimming module to turn on and sends a first PWM signal to the analog dimming module. The analog dimming module then outputs a first driving current flowing to the LED lamp based on the first PWM signal. When the main control module receives a command from the LED lamp to output a small current, it sends a second PWM signal to the analog dimming module. The analog dimming module then outputs a reference current based on the second PWM signal. The main control module also sends a third PWM signal to the PWM dimming module, which turns on and off according to the third PWM signal to adjust the second driving current flowing to the LED lamp based on the reference current. Wherein, 0 ≤ second driving current ≤ reference current < first driving current. This application combines analog dimming and PWM dimming to perform hybrid dimming control on LED lights, effectively avoiding the inherent defects of a single dimming method under extreme current, thereby achieving precise dimming of the light source over a wide current range. Attached Figure Description

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0018] Figure 1 This is one of the structural schematic diagrams of a light source dimming control circuit provided in an embodiment of this application; Figure 2 This is a second schematic diagram of a light source dimming control circuit provided in an embodiment of this application; Figure 3 One of the circuit diagrams of a light source dimming control circuit provided in the embodiments of this application; Figure 4 This is a second circuit diagram of a light source dimming control circuit provided in an embodiment of this application.

[0019] Icons: 10 - Light source dimming control circuit; 100 - Main control module; 200 - Analog dimming module; 210 - Digital-to-analog converter; 220 - Driver unit; 221 - Current driver; 222 - BUCK step-down circuit; 300 - PWM dimming module; Q1 - First switching transistor; Q2 - Second switching transistor; Q3 - Third switching transistor; L - Inductor; R1 - Current sensing resistor; R2 - Temperature sensing resistor; C1 - First capacitor; C2 - Second capacitor. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] In the description of this application, it should be noted that relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0022] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0023] As described in the background section, existing light source dimming methods mainly employ analog dimming or PWM dimming, but both of these dimming methods have certain drawbacks, which are analyzed in detail below: Analog dimming suffers from leakage current in the driver chip, which can lead to excessive residual current at low brightness levels, affecting spectral accuracy. In other words, when LED lights require a small driving current, analog dimming struggles to achieve precise current control, resulting in poor linearity in low-brightness adjustment.

[0024] PWM dimming requires a higher frequency to avoid flickering, but this results in a slow current response, causing it to operate in a non-linear range and making precise current control impossible. In other words, when LED lights require a large drive current, PWM dimming will compress the effective current settling time due to the excessively high switching frequency, leading to a decrease in output accuracy.

[0025] Therefore, how to accurately dim a light source over a wide current range is a technical problem that urgently needs to be solved by those skilled in the art.

[0026] To resolve the above technical issues, please refer to Figure 1 This application provides a light source dimming control circuit 10, including: a main control module 100, an analog dimming module 200 and a PWM dimming module 300.

[0027] The main control module 100 is connected to the analog dimming module 200 and the PWM dimming module 300, respectively. Both the analog dimming module 200 and the PWM dimming module 300 are connected to the LED lights.

[0028] When the main control module 100 receives a command to output a large current from the LED lamp (i.e., the LED lamp requires a large driving current), the main control module 100 controls the PWM dimming module 300 to turn on and sends a first PWM signal to the analog dimming module 200. The analog dimming module 200 outputs a first driving current to the LED lamp according to the first PWM signal.

[0029] When the main control module 100 receives a command from the LED lamp to output a small current (i.e., the LED lamp requires a small drive current), the main control module 100 sends a second PWM signal to the analog dimming module 200. The analog dimming module 200 outputs a reference current based on the second PWM signal. The main control module 100 also sends a third PWM signal to the PWM dimming module 300, which turns on and off according to the third PWM signal to adjust the second drive current flowing to the LED lamp based on the reference current. Wherein, 0 ≤ second drive current ≤ reference current < first drive current.

[0030] Based on the above design, this application combines analog dimming and PWM dimming to perform hybrid dimming control on LED lights, thereby achieving precise dimming of the light source over a wide current range. A detailed analysis follows: When the LED lamp requires a large driving current, this application adopts a control method of "analog dimming as the main method and PWM dimming as the auxiliary method". Specifically, the main control module 100 first controls the PWM dimming module 300 to be continuously turned on, and then sends a first PWM signal (e.g., a duty cycle of 20% to 100%) to the analog dimming module 200. The analog dimming module 200 converts the first PWM signal to output a first driving current (i.e., a large current) flowing to the LED lamp. The magnitude of the first driving current determines the luminous intensity of the LED lamp, and the magnitude of the first driving current is determined by the duty cycle of the first PWM signal.

[0031] When the LED lamp requires a small driving current, this application adopts a control method of "PWM dimming as the main method and analog dimming as the auxiliary method". Specifically, the main control module 100 first sends a second PWM signal (e.g., a duty cycle of 20%) to the analog dimming module 200. The analog dimming module 200 converts the second PWM signal to output a reference current with a fixed current value. Next, the main control module 100 sends a third PWM signal (e.g., a duty cycle of 0-100%) to the PWM dimming module 300 to control the PWM dimming module 300 to turn on and off, thereby adjusting the second driving current (i.e., a small current) flowing to the LED lamp based on the reference current. The magnitude of the second driving current determines the luminous intensity of the LED lamp, and the second driving current = reference current * the duty cycle of the third PWM signal. That is, this application uses the analog dimming module 200 to first set a stable reference current, and then uses the PWM dimming module 300 to fine-tune the reference current to obtain the second driving current. At this point, the current controlled by the PWM dimming module 300 does not need to undergo a slow build-up process from 0 to its maximum value, but instead rapidly switches between a stable reference current and 0. Since the reference current is a well-established and stable current, the rising edge of the PWM waveform is extremely steep, allowing the second drive current to be established instantaneously. This results in a highly linear relationship between the duty cycle of the second drive current and the third PWM signal, thereby achieving precise control of small currents.

[0032] Therefore, this application effectively avoids the inherent defects of a single dimming method under extreme current by combining analog dimming and PWM dimming, thereby achieving precise dimming of the light source over a wide current range.

[0033] For a better understanding, please refer to Figure 2 In one optional embodiment, the analog dimming module 200 includes a digital-to-analog converter 210 and a drive unit 220. The digital-to-analog converter 210 is connected to both the main control module 100 and the drive unit 220, and the drive unit 220 is also connected to the LED light.

[0034] The digital-to-analog converter 210 is used to convert the PWM signal sent by the main control module 100 into an analog voltage and send the analog voltage to the drive unit 220.

[0035] The drive unit 220 is used to output a first drive current or a reference current to the LED lamp according to the analog voltage.

[0036] Understandably, the PWM signal sent by the main control module 100 to the digital-to-analog converter 210 may be either a first PWM signal or a second PWM signal. If the main control module 100 sends the first PWM signal, the drive unit 220 outputs a first drive current; if the main control module 100 sends the second PWM signal, the drive unit 220 outputs a reference current.

[0037] In another alternative implementation, please refer to Figure 3 The drive unit 220 includes a current driver 221 and a BUCK step-down circuit 222, and the PWM dimming module 300 includes a first switching transistor Q1.

[0038] The input terminal of the current driver 221 is connected to the output terminal of the digital-to-analog converter 210, the output terminal of the current driver 221 is connected to the control terminal of the BUCK step-down circuit 222, the input terminal of the BUCK step-down circuit 222 is connected to the reference power supply, the output terminal of the BUCK step-down circuit 222 is connected to the anode of the LED lamp, the cathode of the LED lamp is connected to the first terminal of the first switching transistor Q1, the second terminal of the first switching transistor Q1 is grounded, and the control terminal of the first switching transistor Q1 is connected to the main control module 100.

[0039] The current driver 221 is used to output a drive PWM signal to the BUCK buck circuit 222 according to the analog voltage.

[0040] The BUCK step-down circuit 222 is used to step down the reference voltage according to the drive PWM signal.

[0041] Furthermore, the driving PWM signal includes: a first driving PWM signal and a second driving PWM signal. The BUCK buck circuit 222 includes: a second switch Q2, a third switch Q3, and an inductor L.

[0042] The control terminals of the second switch Q2 and the third switch Q3 are connected to the first and second output terminals of the current driver 221, respectively. The first terminal of the second switch Q2 is connected to the reference power supply. The second terminal of the second switch Q2 is connected to one end of the inductor L and the first terminal of the third switch Q3, respectively. The second terminal of the third switch Q3 is grounded. The other end of the inductor L is connected to the anode of the LED.

[0043] The current driver 221 is used to output a first drive PWM signal and a second drive PWM signal to the control terminals of the second switch Q2 and the third switch Q3 respectively according to the analog voltage.

[0044] The duty cycle of the first driving PWM signal and the duty cycle of the second driving PWM signal are complementary (i.e., the duty cycle of the second driving PWM signal = 1 - the duty cycle of the first driving PWM signal) to ensure that the second switch Q2 and the third switch Q3 will not be turned on at the same time.

[0045] Optionally, the first switch Q1, the second switch Q2, and the third switch Q3 are all NMOS transistors.

[0046] As an optional implementation, the drive unit 220 further includes a current sensing resistor R1. One end of the current sensing resistor R1 is connected to the inductor L, the other end of the current sensing resistor R1 is connected to the anode of the LED, and the current driver 221 is connected to both ends of the current sensing resistor R1.

[0047] The current driver 221 is used to adjust the duty cycle of the first drive PWM signal according to the voltage difference across the current sensing resistor R1 until the voltage difference across the current sensing resistor R1 is equal to the analog voltage.

[0048] Based on the above design, the overall working principle of the analog dimming module 200 provided in this application embodiment is as follows: The digital-to-analog converter 210 converts the PWM signal sent by the main control module 100 into an analog voltage (which is the target output voltage of the BUCK buck circuit 222). The current driver 221 outputs a first driving PWM signal and a second PWM signal with corresponding duty cycles to the second switch Q2 and the third switch Q3 respectively according to the analog voltage. The BUCK buck circuit 222 performs a step-down conversion on the reference voltage according to the duty cycle of the first driving PWM signal to obtain the actual output voltage. Wherein, the actual output voltage of the BUCK buck circuit 222 = reference voltage * duty cycle of the first driving PWM signal. In this process, the current driver 221 detects the voltage difference across the current sensing resistor R1 in real time (i.e., the actual output voltage of the BUCK buck circuit 222), and adjusts the duty cycle of the first driving PWM signal with negative feedback according to the voltage difference across the current sensing resistor R1 until the voltage difference across the current sensing resistor R1 (i.e., the actual output voltage) equals the analog voltage (i.e., the target output voltage).

[0049] Furthermore, to achieve high-precision sampling and closed-loop control, in one optional implementation, the current driver 221 and the current sensing resistor R1 are connected using a Kelvin four-wire connection. By physically isolating the current driving path from the voltage sensing path, the actual voltage drop across the current sensing resistor R1 generated by the load current (i.e., the driving current flowing to the LED) is directly sampled, effectively eliminating measurement errors introduced by lead resistance and contact resistance.

[0050] Optionally, the driving unit 220 further includes a first capacitor C1 and a second capacitor C2. The first capacitor C1 is connected in parallel across the current sensing resistor R1, one end of the second capacitor C2 is connected to one end of the current sensing resistor R1 and the anode of the LED, and the other end of the second capacitor C2 is grounded.

[0051] To better understand, the following will be combined with... Figure 3 The overall working principle of the light source dimming control circuit 10 provided in this application is explained.

[0052] When the main control module 100 receives a command to output a large current from the LED, it outputs a high level to the first switching transistor Q1 to turn it on. Next, the main control module 100 outputs a first PWM signal (e.g., a duty cycle of 20% to 100%) to the digital-to-analog converter 210. The digital-to-analog converter 210 converts the first PWM signal into a corresponding analog voltage (e.g., 0.3 to 1.5V) and sends it to the current driver 221. The current driver 221 outputs a drive PWM signal to the buck converter 222 based on the analog voltage. The buck converter 222 performs a step-down conversion on the reference voltage based on the duty cycle of the drive PWM signal. Furthermore, the current driver 221 adjusts the duty cycle of the drive PWM signal based on the voltage difference across the current sensing resistor R1 to ensure that the actual output voltage of the buck converter 222 equals the analog voltage, ultimately providing the first drive current to the LED.

[0053] When the main control module 100 receives a command to output a small current from the LED, it outputs a second PWM signal with a fixed duty cycle (e.g., a fixed duty cycle of 20%) to the digital-to-analog converter 210. The digital-to-analog converter 210 converts the second PWM signal into a corresponding analog voltage (e.g., 0.3V) and sends it to the current driver 221. The current driver 221 controls the BUCK step-down circuit 222 to operate according to the analog voltage, providing a constant reference current. Next, the main control module 100 outputs a third PWM signal (e.g., a duty cycle of 0-100%) to the first switching transistor Q1 to control the on / off state of Q1, thereby adjusting the second drive current flowing to the LED based on the reference current. Wherein, the second drive current = reference current * the duty cycle of the third PWM signal.

[0054] In addition, for the thermal protection and intelligent brightness adjustment of LED lights, please refer to [link / reference needed]. Figure 4 In another optional embodiment, the light source dimming control circuit 10 further includes a temperature sensing resistor R2. The temperature sensing resistor R2 is located close to the LED light, and both ends of the temperature sensing resistor R2 are connected to the main control module 100.

[0055] The main control module 100 monitors the resistance change of the temperature sensing resistor R2 in real time to obtain the actual operating temperature of the LED. When the actual operating temperature exceeds a preset threshold, the main control module 100 can reduce the drive current or control the first switching transistor Q1 to turn off to prevent the LED from overheating and being damaged. In addition, the main control module 100 can also dynamically fine-tune the brightness of the LED according to the actual operating temperature to optimize the consistency of luminous efficacy while ensuring lifespan.

[0056] Optionally, this application embodiment also provides a light source dimming control system, which includes a light source dimming control circuit 10 as described in any of the foregoing embodiments.

[0057] In summary, this application provides a light source dimming control circuit and system, which includes a main control module, an analog dimming module, and a PWM dimming module. The main control module is connected to both the analog dimming module and the PWM dimming module, and both are connected to an LED lamp. When the main control module receives a command from the LED lamp to output a large current, it controls the PWM dimming module to turn on and sends a first PWM signal to the analog dimming module. The analog dimming module then outputs a first driving current flowing to the LED lamp based on the first PWM signal. When the main control module receives a command from the LED lamp to output a small current, it sends a second PWM signal to the analog dimming module. The analog dimming module then outputs a reference current based on the second PWM signal. The main control module also sends a third PWM signal to the PWM dimming module, which turns on and off according to the third PWM signal to adjust the second driving current flowing to the LED lamp based on the reference current. Wherein, 0 ≤ second driving current ≤ reference current < first driving current. This application combines analog dimming and PWM dimming to perform hybrid dimming control on LED lights, effectively avoiding the inherent defects of a single dimming method under extreme current, thereby achieving precise dimming of the light source over a wide current range.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0059] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A light source dimming control circuit, characterized in that, include: Main control module, analog dimming module, and PWM dimming module; The main control module is connected to the analog dimming module and the PWM dimming module respectively, and both the analog dimming module and the PWM dimming module are connected to the LED light; When the main control module receives a command to output a large current from the LED lamp, the main control module controls the PWM dimming module to turn on and sends a first PWM signal to the analog dimming module. The analog dimming module outputs a first driving current to the LED lamp according to the first PWM signal. When the main control module receives a command to output a small current from the LED, the main control module sends a second PWM signal to the analog dimming module, and the analog dimming module outputs a reference current based on the second PWM signal. The main control module also sends a third PWM signal to the PWM dimming module, and the PWM dimming module turns on and off according to the third PWM signal to adjust the second driving current flowing to the LED based on the reference current. Wherein, 0 ≤ second driving current ≤ reference current < first driving current.

2. The light source dimming control circuit according to claim 1, characterized in that, The analog dimming module includes: a digital-to-analog converter and a drive unit; The digital-to-analog converter is connected to the main control module and the drive unit respectively, and the drive unit is also connected to the LED light; The digital-to-analog converter is used to convert the PWM signal sent by the main control module into an analog voltage, and send the analog voltage to the drive unit; The driving unit is used to output the first driving current or the reference current to the LED lamp according to the analog voltage.

3. The light source dimming control circuit according to claim 2, characterized in that, The driving unit includes a current driver and a BUCK step-down circuit; the PWM dimming module includes a first switching transistor. The input terminal of the current driver is connected to the output terminal of the digital-to-analog converter, the output terminal of the current driver is connected to the control terminal of the BUCK buck circuit, the input terminal of the BUCK buck circuit is connected to the reference power supply, and the output terminal of the BUCK buck circuit is connected to the anode of the LED lamp; the cathode of the LED lamp is connected to the first terminal of the first switching transistor, the second terminal of the first switching transistor is grounded, and the control terminal of the first switching transistor is connected to the main control module. The current driver is used to output a drive PWM signal to the BUCK buck circuit according to the analog voltage; The BUCK step-down circuit is used to step down the reference voltage according to the drive PWM signal.

4. The light source dimming control circuit according to claim 3, characterized in that, The driving PWM signal includes: a first driving PWM signal and a second driving PWM signal; The BUCK step-down circuit includes: a second switching transistor, a third switching transistor, and an inductor; The control terminals of the second and third switching transistors are respectively connected to the first and second output terminals of the current driver. The first terminal of the second switching transistor is connected to the reference power supply. The second terminal of the second switching transistor is connected to one end of the inductor and the first terminal of the third switching transistor. The second terminal of the third switching transistor is grounded. The other end of the inductor is connected to the anode of the LED. The current driver is used to output the first driving PWM signal and the second driving PWM signal to the control terminals of the second switch and the third switch respectively according to the analog voltage; wherein the duty cycle of the first driving PWM signal and the duty cycle of the second driving PWM signal are complementary.

5. The light source dimming control circuit according to claim 4, characterized in that, The driving unit also includes a current sensing resistor; One end of the current sensing resistor is connected to the inductor, the other end of the current sensing resistor is connected to the anode of the LED, and the current driver is connected to both ends of the current sensing resistor. The current driver is used to adjust the duty cycle of the first driving PWM signal according to the voltage difference across the current sensing resistor until the voltage difference across the current sensing resistor is equal to the analog voltage.

6. The light source dimming control circuit according to claim 5, characterized in that, The current driver and the current sensing resistor are connected using a Kelvin four-wire system.

7. The light source dimming control circuit according to claim 5, characterized in that, The driving unit also includes a first capacitor and a second capacitor; The first capacitor is connected in parallel across the current sensing resistor, one end of the second capacitor is connected to one end of the current sensing resistor and the anode of the LED, and the other end of the second capacitor is grounded.

8. The light source dimming control circuit according to claim 4, characterized in that, The first switch, the second switch, and the third switch are all NMOS transistors.

9. The light source dimming control circuit according to claim 1, characterized in that, The light source dimming control circuit also includes a temperature sensing resistor; The temperature sensing resistor is located close to the LED light, and both ends of the temperature sensing resistor are connected to the main control module.

10. A light source dimming control system, characterized in that, The light source dimming control system includes the light source dimming control circuit as described in any one of claims 1-9.

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