Constant current control circuit and constant current control device

Abstract

The application provides a constant current control circuit and a constant current control device. The circuit comprises a voltage conversion module, a current sampling module, a first constant current control module, a second constant current control module and an adjusting module. The current sampling module is used for collecting a first current flowing through an LED light source module, outputting a first sampling current to the first constant current control module according to the first current, and outputting a second sampling current to the second constant current control module; the first constant current control module receives a first dimming signal and generates a first control signal based on the first sampling current and the first dimming signal; the second constant current control module receives a second dimming signal and generates a second control signal based on the second sampling current and the second dimming signal; and the adjusting module adjusts a feedback voltage according to the first control signal or the second control signal. The constant current control circuit of the application adopts a two-stage constant current control architecture with independent closed loops, greatly improves the range coverage capability of current regulation, and meets the use demand of wide range brightness regulation.

Description

Technical Field

[0001] This application belongs to the field of constant current control technology, and in particular relates to a constant current control circuit and a constant current control device. Background Technology

[0002] In fields such as LED (Light-Emitting Diode) lighting and photographic fill light, the core of LED light source brightness adjustment relies on constant current control circuits. As a current-driven load, the brightness of an LED is directly related to the magnitude of the current flowing through it. Therefore, a constant current control circuit is needed to ensure that the LED current is stable and precisely adjustable to meet the lighting needs of different scenarios. Existing LED constant current control solutions typically use DC-DC chips with integrated dimming functions. While this solution simplifies some circuitry, its current adjustment range is limited by the chip's own design characteristics, failing to meet the requirements for wide-range brightness adjustment. Summary of the Invention

[0003] This application provides a constant current control circuit and a constant current control device, which can solve the problem that existing LED constant current control schemes usually use DCDC chips with integrated dimming functions, which have limited current adjustment range coverage and cannot meet the usage requirements of wide range brightness adjustment.

[0004] In a first aspect, embodiments of this application provide a constant current control circuit, including a voltage conversion module (101), a current sampling module (102), a first constant current control module (103), a second constant current control module (104), and an adjustment module (105), wherein:

[0005] The current sampling module (102) is used to collect the first current flowing through the LED light source module (20), and is electrically connected to the first constant current control module (103) and the second constant current control module (104) respectively. The current sampling module (102) outputs a first sampling current to the first constant current control module (103) and a second sampling current to the second constant current control module (104) according to the first current.

[0006] The first constant current control module (103) is used to receive the first dimming signal and generate a first control signal based on the first sampling current and the first dimming signal;

[0007] The second constant current control module (104) is used to receive the second dimming signal and generate a second control signal based on the second sampling current and the second dimming signal;

[0008] The adjustment module (105) is electrically connected to the voltage conversion module (101), the first constant current control module (103) and the second constant current control module (104) respectively. The adjustment module (105) is used to adjust the feedback voltage of the voltage conversion module (101) according to the first control signal or the second control signal.

[0009] In one possible implementation of the first aspect, the current sampling module (102) includes a current sampling unit (1021), a first differential amplification unit (1022), and a second differential amplification unit (1023), wherein:

[0010] The current sampling unit (1021) is electrically connected to the first differential amplifier unit (1022) and the second differential amplifier unit (1023) respectively. The current sampling unit (1021) is used to collect the first current flowing through the LED light source module (20) and output the second current to the first differential amplifier unit (1022) and the second differential amplifier unit (1023) respectively.

[0011] The first differential amplifier unit (1022) is electrically connected to the first constant current control module (103). The first differential amplifier unit (1022) is used to amplify the second current by a first preset factor to obtain the first sampling current, and transmit the first sampling current to the first constant current control module (103).

[0012] The second differential amplifier unit (1023) is electrically connected to the second constant current control module (104). The second differential amplifier unit (1023) is used to amplify the second current by a second preset factor to obtain the second sampling current, and transmit the second sampling current to the second constant current control module (104). The first preset factor is greater than the second preset factor.

[0013] In one possible implementation of the first aspect, the current sampling unit (1021) includes a first resistor and a second resistor. The first end of the first resistor and the first end of the second resistor are respectively electrically connected to the first differential amplifier unit (1022) and the second differential amplifier unit (1023). The first end of the first resistor and the first end of the second resistor are both used to be electrically connected to the LED light source module (20). The second end of the first resistor and the second end of the second resistor are both grounded.

[0014] In one possible implementation of the first aspect, the first differential amplifier unit (1022) includes a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The non-inverting input terminal of the first operational amplifier is electrically connected to the second terminal of the fourth resistor and the first terminal of the fifth resistor, respectively. The inverting input terminal of the first operational amplifier is electrically connected to the second terminal of the third resistor and the first terminal of the sixth resistor, respectively. The output terminal of the first operational amplifier is electrically connected to the second terminal of the sixth resistor and the first constant current control module (103), respectively. The first terminal of the third resistor and the second terminal of the fifth resistor are both grounded. The first terminal of the fourth resistor is electrically connected to the current sampling unit (1021).

[0015] In one possible implementation of the first aspect, the second differential amplifier unit (1023) includes a second operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor. The non-inverting input terminal of the second operational amplifier is electrically connected to the second terminal of the eighth resistor and the first terminal of the ninth resistor, respectively. The inverting input terminal of the second operational amplifier is electrically connected to the second terminal of the seventh resistor and the first terminal of the tenth resistor, respectively. The output terminal of the second operational amplifier is electrically connected to the second terminal of the tenth resistor and the second constant current control module (104), respectively. The first terminal of the seventh resistor and the second terminal of the ninth resistor are both grounded. The first terminal of the eighth resistor is electrically connected to the current sampling unit (1021).

[0016] In one possible implementation of the first aspect, the first constant current control module (103) includes a third operational amplifier, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a first capacitor, and a second capacitor. The first end of the eleventh resistor is used to receive the first dimming signal. The second end of the eleventh resistor is electrically connected to the first end of the first capacitor and the first end of the twelfth resistor, respectively. The first end of the thirteenth resistor is electrically connected to the first end of the second capacitor and the second end of the twelfth resistor, respectively. The second end of the thirteenth resistor is electrically connected to the inverting input of the third operational amplifier. The non-inverting input of the third operational amplifier is electrically connected to the second end of the fourteenth resistor and the first end of the fifteenth resistor, respectively. The output of the third operational amplifier is electrically connected to the adjustment module (105). The second ends of the first capacitor and the second capacitor are both grounded. The first end of the fourteenth resistor is electrically connected to the current sampling module (102). The second end of the fifteenth resistor is used to be electrically connected to the first power supply.

[0017] In one possible implementation of the first aspect, the second constant current control module (104) includes a fourth operational amplifier, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a third capacitor, and a fourth capacitor. The first end of the sixteenth resistor is used to receive the second dimming signal. The second end of the sixteenth resistor is electrically connected to the first end of the third capacitor and the first end of the seventeenth resistor, respectively. The first end of the eighteenth resistor is electrically connected to the first end of the fourth capacitor and the second end of the seventeenth resistor, respectively. The second end of the eighteenth resistor is electrically connected to the inverting input of the fourth operational amplifier. The non-inverting input of the fourth operational amplifier is electrically connected to the second end of the nineteenth resistor and the first end of the twentieth resistor, respectively. The output of the fourth operational amplifier is electrically connected to the adjustment module (105). The second ends of the third capacitor and the fourth capacitor are both grounded. The first end of the nineteenth resistor is electrically connected to the current sampling module (102). The second end of the twentieth resistor is used to be electrically connected to the second power supply.

[0018] In one possible implementation of the first aspect, the adjustment module (105) includes a first diode, a second diode, a twenty-first resistor, a twenty-second resistor, and a twenty-third resistor. The anode of the first diode is electrically connected to the first terminal of the second constant current control module (104) and the second terminal of the second eleventh resistor, respectively. The cathode of the first diode is electrically connected to the first constant current control module (103). The first terminal of the second eleventh resistor is electrically connected to the second terminal of the second eleventh resistor. The second terminal of the second eleventh resistor is electrically connected to the first terminal of the second thirteenth resistor. The anode of the second diode is electrically connected to the second terminal of the second thirteenth resistor. The cathode of the second diode is electrically connected to the voltage conversion module (101).

[0019] In one possible implementation of the first aspect, the voltage conversion module (101) includes a voltage conversion chip, the enable pin of the voltage conversion chip is used to receive an enable signal, the input pin of the voltage conversion chip is used to receive an input voltage, the feedback pin of the voltage conversion chip is electrically connected to the adjustment module (105) to receive the feedback voltage, and the output pin of the voltage conversion chip is used to be electrically connected to the LED light source module (20).

[0020] Secondly, embodiments of this application provide a constant current control device, including the constant current control circuit described in any one of the first aspects.

[0021] The beneficial effects of the embodiments in this application compared with the prior art are:

[0022] The constant current control circuit provided in this application includes a voltage conversion module, a current sampling module, a first constant current control module, a second constant current control module, and an adjustment module. The current sampling module collects a first current flowing through the LED light source module and outputs a first sampled current to the first constant current control module and a second sampled current to the second constant current control module based on the first current.

[0023] The first constant current control module outputs a first control signal to the adjustment module based on the first sampled current and the received first dimming signal. The adjustment module then adjusts the feedback voltage according to the first control signal. Since the supply voltage of the LED light source module output by the voltage conversion module is affected by the feedback voltage, a change in the feedback voltage will drive a change in the supply voltage, thereby causing a corresponding change in the first current flowing through the LED light source module. The current sampling module collects the changed first current and outputs a new first sampled current. The first constant current control module adjusts the output of the first control signal based on the updated first sampled current, prompting the adjustment module to continuously correct the feedback voltage, thus forming a complete closed-loop constant current control circuit.

[0024] The second constant current control module outputs a second control signal to the adjustment module based on the second sampled current and the received second dimming signal. The adjustment module then adjusts the feedback voltage according to the second control signal. Similarly, the change in feedback voltage drives a change in the supply voltage, which in turn causes a corresponding change in the first current flowing through the LED light source module. The current sampling module collects the changed first current and outputs a new second sampled current. The second constant current control module adjusts the output of the second control signal based on the updated second sampled current, prompting the adjustment module to continuously correct the feedback voltage, thereby forming a complete closed-loop constant current control circuit.

[0025] Therefore, the constant current control circuit provided in this application embodiment innovatively adopts an independent closed-loop two-stage constant current control architecture, which can construct two complete closed-loop constant current control loops to achieve differentiated regulation of different currents, breaking through the current adjustment range limitation of existing solutions, greatly improving the range coverage capability of current adjustment, and thus fully meeting the usage requirements of wide-range brightness adjustment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic block diagram of a constant current control circuit provided in one embodiment of this application;

[0028] Figure 2 This is a schematic block diagram of a constant current control circuit provided in another embodiment of this application;

[0029] Figure 3 This is a circuit connection diagram of a current sampling unit provided in an embodiment of this application;

[0030] Figure 4 This is a circuit connection diagram of the first differential amplifier unit provided in an embodiment of this application;

[0031] Figure 5 This is a circuit connection diagram of the second differential amplifier unit provided in an embodiment of this application;

[0032] Figure 6 This is a circuit connection diagram of the first constant current control module provided in an embodiment of this application;

[0033] Figure 7 This is a circuit connection diagram of the second constant current control module provided in an embodiment of this application;

[0034] Figure 8 This is a circuit connection diagram of an adjustment module provided in an embodiment of this application;

[0035] Figure 9 This is a circuit connection diagram of a voltage conversion module provided in an embodiment of this application;

[0036] Figure 10 This is a schematic diagram of MCU control signals provided in an embodiment of this application.

[0037] In the diagram, 10 is the constant current control circuit; 101 is the voltage conversion module; 102 is the current sampling module; 1021 is the current sampling unit; 1022 is the first differential amplifier unit; 1023 is the second differential amplifier unit; 103 is the first constant current control module; 104 is the second constant current control module; 105 is the adjustment module; and 20 is the LED light source module. Detailed Implementation

[0038] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0039] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0040] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0041] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0042] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0044] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0045] Figure 1 A schematic block diagram of a constant current control circuit 10 according to an embodiment of this application is shown. See also Figure 1 As shown, the constant current control circuit 10 includes a voltage conversion module 101, a current sampling module 102, a first constant current control module 103, a second constant current control module 104, and an adjustment module 105.

[0046] Specifically, the voltage conversion module 101 is used to output a power supply voltage (LED+) to the LED light source module 20, thereby powering the LED light source module 20. Under this power supply state, current will flow through the LED light source module 20. The current sampling module 102 collects the first current flowing through the LED light source module 20, and outputs a first sampling current Imin to the first constant current control module 103 and a second sampling current Imax to the second constant current control module 104 based on the first current.

[0047] The first constant current control module 103 outputs a first control signal to the adjustment module 105 based on the first sampled current Imin and the received first dimming signal PWM_Min. The adjustment module 105 then adjusts the feedback voltage FB according to the first control signal. Since the power supply voltage of the LED light source module 20 output by the voltage conversion module 101 is affected by the feedback voltage FB, the change in the feedback voltage FB will drive the power supply voltage to change, thereby causing the first current flowing through the LED light source module 20 to change accordingly. The current sampling module 102 collects the changed first current and outputs a new first sampled current Imin. The first constant current control module 103 adjusts the output of the first control signal based on the updated first sampled current Imin, prompting the adjustment module 105 to continuously correct the feedback voltage FB, thereby forming a complete closed-loop constant current control circuit.

[0048] The second constant current control module 104 outputs a second control signal to the adjustment module 105 based on the second sampled current Imax and the received second dimming signal PWM_Max. The adjustment module 105 then adjusts the feedback voltage FB according to the second control signal. Similarly, the change in the feedback voltage FB will drive a change in the supply voltage, thereby causing a corresponding change in the first current flowing through the LED light source module 20. The current sampling module 102 collects the changed first current and outputs a new second sampled current Imax. The second constant current control module 104 adjusts the output of the second control signal based on the updated second sampled current Imax, prompting the adjustment module 105 to continuously correct the feedback voltage FB, thus forming a complete closed-loop constant current control circuit.

[0049] Therefore, the constant current control circuit 10 provided in this application embodiment innovatively adopts an independent closed-loop two-stage constant current control architecture, which can construct two complete closed-loop constant current control loops to achieve differentiated regulation of different currents, breaking through the current adjustment range limitation of the existing solution, greatly improving the range coverage capability of current adjustment, and thus fully meeting the usage requirements of wide-range brightness adjustment.

[0050] It should be noted that a preset brightness threshold can be set for the LED light source module 20. If the actual brightness of the LED light source module 20 is lower than the preset brightness threshold (i.e., low brightness condition), the first constant current control module 103 starts working and outputs a first control signal. The adjustment module 105 adjusts the feedback voltage FB according to the first control signal, ultimately forming a closed-loop constant current control loop for small currents to stably output current that meets the low brightness requirements. During this process, the second constant current control module 104 is in an open-loop state and will not interfere with the closed-loop control dominated by the first constant current control module 103.

[0051] As the brightness adjustment requirements of the LED light source module 20 increase, when the duty cycle of the first dimming signal PWM_Min reaches 100%, the brightness of the LED light source module 20 rises to the preset brightness threshold (i.e., high brightness condition). At this time, the second constant current control module 104 starts working and outputs a second control signal. The adjustment module 105 adjusts the feedback voltage FB according to the second control signal, ultimately forming a closed-loop constant current control loop for high current. During this process, the first constant current control module 103 is in an open-loop state and will not interfere with the closed-loop control dominated by the second constant current control module 104.

[0052] Therefore, the constant current control circuit 10 provided in this application embodiment not only innovatively adopts a two-stage constant current control architecture, but also divides low-brightness and high-brightness operating conditions by setting a switching threshold brightness, realizing the mutually exclusive independent operation of the two-stage control modules. Specifically, a dedicated first constant current control module 103 is configured for the low-brightness operating condition, enabling high-precision control of minute currents. This significantly reduces dimming spikes and stably covers the extremely low current range, perfectly adapting to low-light scenarios with stringent brightness accuracy requirements, such as night scene lighting, precision instrument indicator lights, and low-light environment monitoring. This effectively expands the circuit's applicability and solves the technical pain point of large dimming spikes (high minimum brightness values) in existing solutions using dedicated chips. For the high-brightness operating condition, the second constant current control module 104 takes the lead, ensuring the stability and reliability of the high-current output. Simultaneously, this two-stage control architecture increases the number of adjustment components in the low-current range, thereby significantly improving the precision of brightness adjustment, making LED brightness switching smoother and light combination more accurate.

[0053] In addition, the mutual exclusion mechanism of the two-stage constant current control module can avoid signal interference and conflict caused by the simultaneous intervention of multiple loops, ensure the continuity and smoothness of brightness switching between low and high ranges, avoid sudden brightness changes or flashing during the switching process, and significantly improve the user experience.

[0054] In one embodiment of this application, such as Figure 2As shown, the current sampling module 102 includes a current sampling unit 1021, a first differential amplification unit 1022, and a second differential amplification unit 1023.

[0055] Specifically, the current sampling unit 1021 is used to collect the first current flowing through the LED light source module 20, use the collected first current as the basic sampling signal, and convert it into a second current (CS+ and CS-), which are transmitted to the first differential amplifier unit 1022 and the second differential amplifier unit 1023 respectively, providing the original signal support for subsequent current amplification and control.

[0056] The first differential amplifier unit 1022 is used to receive the second current, and then differentially amplify the second current according to the first preset multiple to obtain the first sampling current Imin adapted to the adjustment requirements of low brightness scene, and transmit it to the first constant current control module 103 to provide a precise current feedback signal for the closed-loop constant current control of the small current loop.

[0057] The second differential amplifier unit 1023 receives the second current and then differentially amplifies it according to a second preset factor to obtain a second sampling current Imax adapted to the control requirements of high-brightness scenarios. This second sampling current Imax is then transmitted to the second constant current control module 104 to provide a precise current feedback signal for the closed-loop constant current control of the high-current loop. The first preset factor is greater than the second preset factor to achieve differentiated and precise amplification across different current ranges.

[0058] For example, the first preset multiple and the second preset multiple can be flexibly set according to the current control requirements of the actual application scenario to adapt to the precise feedback of different brightness ranges. For example, the first preset multiple can be set to 590 times. Through this high-magnification differential amplification processing, the second current output by the current sampling unit 1021 can be accurately amplified by 590 times to obtain the first sampling current Imin adapted to the control of low brightness scenarios, providing sensitive and accurate current feedback for the closed-loop constant current control of the small current loop. Correspondingly, the second preset multiple can be set to 10 times. Through this amplification multiple adapted to the large current scenario, the second current can be amplified by 10 times to obtain the second sampling current Imax, which meets the stable control requirements of the large current loop in the high brightness scenario, ensuring that the two-level control loops achieve efficient and accurate feedback and control for different current ranges.

[0059] The following is combined Figures 3 to 10 The circuit diagram shown provides a detailed description of the working principle of the constant current control circuit 10 provided in the embodiments of this application.

[0060] In one embodiment of this application, such as Figure 3As shown, the current sampling unit 1021 includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 and the first end of the second resistor R2 are respectively electrically connected to the first differential amplifier unit 1022 and the second differential amplifier unit 1023. The first end of the first resistor R1 and the first end of the second resistor R2 are both used to be electrically connected to the LED light source module 20. The second end of the first resistor R1 and the second end of the second resistor R2 are both grounded.

[0061] Specifically, both the first resistor R1 and the second resistor R2 serve as current sampling resistors. Their first terminals are electrically connected to the LED light source module 20 and simultaneously connected to the first differential amplifier unit 1022 and the second differential amplifier unit 1023. When current flows through the LED light source module 20, it simultaneously passes through these two resistors, generating a voltage signal (second current) corresponding to the magnitude of the current flowing through the LED at its terminals. This signal is then synchronously transmitted to the first differential amplifier unit 1022 and the second differential amplifier unit 1023, providing the basis for current sampling for subsequent differential amplification processing at different factors.

[0062] In one embodiment of this application, such as Figure 4 As shown, the first differential amplifier unit 1022 includes a first operational amplifier U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. The non-inverting input terminal (+IN) of the first operational amplifier U1 is electrically connected to the second terminal of the fourth resistor R4 and the first terminal of the fifth resistor R5. The inverting input terminal (-IN) of the first operational amplifier U1 is electrically connected to the second terminal of the third resistor R3 and the first terminal of the sixth resistor R6. The output terminal (OUT) of the first operational amplifier U1 is electrically connected to the second terminal of the sixth resistor R6 and the first constant current control module 103. The first terminals of the third resistor R3 and the fifth resistor R5 are both grounded. The first terminal of the fourth resistor R4 is electrically connected to the current sampling unit 1021. The power supply terminal (+Vs) of the first operational amplifier U1 is connected to a +5V power supply, and the ground terminal (-Vs) of the first operational amplifier U1 is grounded.

[0063] Specifically, the first operational amplifier U1 in the first differential amplifier unit 1022 serves as the core amplification device, enabling differential signal amplification and signal conditioning. The third resistor R3 and the fifth resistor R5 are both ground bias resistors, providing a stable static operating point for the inverting and non-inverting input terminals of the first operational amplifier U1, preventing input signal drift from affecting amplification accuracy. The fourth resistor R4 serves as the signal input resistor, receiving the second current and converting it into a voltage signal, which is then transmitted to the non-inverting input terminal of the first operational amplifier U1 to achieve effective sampling signal input. The sixth resistor R6 serves as the feedback resistor, bridging the output terminal and the inverting input terminal of the first operational amplifier U1. Together with the fourth resistor R4 and the third resistor R3, it forms a differential amplification circuit. The amplification factor (i.e., the first preset factor) of the first differential amplifier unit 1022 is determined by the resistance ratio, ultimately causing the first operational amplifier U1 to output the precisely amplified first sampling current Imin, which is then transmitted to the first constant current control module 103.

[0064] For example, designers can select the resistance values ​​of the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 according to the actual situation. For instance, the resistance values ​​of the third resistor R3 and the fourth resistor R4 can both be selected as 1kΩ, while the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 can both be selected as 590kΩ. With this set of resistance values, the first preset amplification factor of the first differential amplifier unit 1022 can be accurately achieved to 590 times, thereby meeting the requirements of high amplification and accurate feedback of small currents under low brightness conditions.

[0065] It should be noted that the first differential amplifier unit 1022 also includes C5, C6, C7, C8 and R24, and their connection relationships can be found in [reference needed]. Figure 4 As shown, C5 is connected between the non-inverting and inverting input terminals of the first operational amplifier U1, which can filter out high-frequency interference and common-mode noise in the input signal, improve the signal purity of differential amplification, and avoid noise affecting the accuracy of current sampling. C6 and C7 are power supply filter capacitors, which can filter out high-frequency ripple and interference signals in the +5V power supply, providing a stable and clean operating power supply for the first operational amplifier U1, and ensuring the stability and consistency of the operational amplifier's amplification performance. C8 and R24 are connected in series across the output terminal and inverting input terminal of the first operational amplifier U1 to form an RC phase compensation network, which can suppress the self-oscillation that may occur when the operational amplifier is working, optimize the phase characteristics of the amplification circuit, improve the stability and response speed of the closed-loop negative feedback, and ensure that the first differential amplification unit 1022 can still output a stable and distortion-free first sampling current Imin under high amplification (such as 590 times) conditions.

[0066] In one embodiment of this application, such as Figure 5As shown, the second differential amplifier unit 1023 includes a second operational amplifier U2, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. The non-inverting input terminal (+IN) of the second operational amplifier U2 is electrically connected to the second terminal of the eighth resistor R8 and the first terminal of the ninth resistor R9, respectively. The inverting input terminal (-IN) of the second operational amplifier U2 is electrically connected to the second terminal of the seventh resistor R7 and the first terminal of the tenth resistor R10, respectively. The output terminal (OUT) of the second operational amplifier U2 is electrically connected to the second terminal of the tenth resistor R10 and the second constant current control module 104, respectively. The first terminals of the seventh resistor R7 and the ninth resistor R9 are both grounded. The first terminal of the eighth resistor R8 is electrically connected to the current sampling unit 1021. The power supply terminal (+Vs) of the second operational amplifier U2 is connected to a +5V power supply, and the ground terminal (-Vs) of the second operational amplifier U2 is grounded.

[0067] Specifically, the second operational amplifier U2 in the second differential amplifier unit 1023 serves as the core amplification device, enabling differential signal amplification and signal conditioning. The seventh resistor R7 and the ninth resistor R9 are both ground bias resistors, providing a stable static operating point for the inverting and non-inverting input terminals of the second operational amplifier U2, preventing input signal drift from affecting amplification accuracy. The eighth resistor R8 serves as the signal input resistor, receiving the second current and converting it into a voltage signal, which is then transmitted to the non-inverting input terminal of the second operational amplifier U2, effectively introducing the sampled signal. The tenth resistor R10 serves as the feedback resistor, bridging the output terminal and the inverting input terminal of the second operational amplifier U2. Together with the eighth resistor R8 and the seventh resistor R7, it forms a differential amplification circuit. The amplification factor (i.e., the second preset factor) of the second differential amplifier unit 1023 is determined by the resistance ratio, ultimately causing the output terminal of the second operational amplifier U2 to output the precisely amplified second sampling current Imax, which is then transmitted to the second constant current control module 104.

[0068] For example, designers can select the resistance values ​​of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 according to the actual situation. For instance, the resistance values ​​of the seventh resistor R7 and the eighth resistor R8 can both be selected as 1kΩ, while the resistance values ​​of the ninth resistor R9 and the tenth resistor R10 can both be selected as 10kΩ. With this set of resistance values, the second preset amplification factor of the second differential amplifier unit 1023 can be accurately achieved to 10 times, thereby meeting the requirements of low-magnification amplification and accurate feedback of large current under high brightness conditions.

[0069] It should be noted that the second differential amplifier unit 1023 also includes C9, C10, C11, C12 and R25, and the connection relationship can be found in [reference needed]. Figure 5As shown, C9 is connected between the non-inverting and inverting input terminals of the second operational amplifier U2, which can filter out high-frequency interference and common-mode noise in the input signal, improve the signal purity of differential amplification, and avoid noise affecting the accuracy of current sampling. C10 and C11 are power supply filter capacitors, which can filter out high-frequency ripple and interference signals in the +5V power supply, providing a stable and clean operating power supply for the second operational amplifier U2, and ensuring the stability and consistency of the operational amplifier's amplification performance. C12 and R25 are connected in series across the output terminal and inverting input terminal of the second operational amplifier U2 to form an RC phase compensation network, which can suppress the self-oscillation that may occur when the operational amplifier is working, optimize the phase characteristics of the amplification circuit, improve the stability and response speed of the closed-loop negative feedback, and ensure that the second differential amplification unit 1023 can still output a stable and distortion-free second sampling current Imax under low amplification (such as 10x) conditions.

[0070] In one embodiment of this application, such as Figure 6 As shown, the first constant current control module 103 includes a third operational amplifier U3, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a first capacitor C1, and a second capacitor C2. The first terminal of the eleventh resistor R11 is used to receive the first dimming signal PWM_Min. The second terminal of the eleventh resistor R11 is electrically connected to the first terminal of the first capacitor C1 and the first terminal of the twelfth resistor R12. The first terminal of the thirteenth resistor R13 is electrically connected to the first terminal of the second capacitor C2 and the first terminal of the twelfth resistor R15. The two terminals are electrically connected. The second terminal of the thirteenth resistor R13 is electrically connected to the inverting input terminal (-IN) of the third operational amplifier U3. The non-inverting input terminal (+IN) of the third operational amplifier U3 is electrically connected to the second terminal of the fourteenth resistor R14 and the first terminal of the fifteenth resistor R15. The output terminal (OUT) of the third operational amplifier U3 is electrically connected to the adjustment module 105. The second terminals of the first capacitor C1 and the second terminals of the second capacitor C2 are both grounded. The first terminal of the fourteenth resistor R14 is electrically connected to the current sampling module 102. The second terminal of the fifteenth resistor R15 is used to connect to the first power supply. The power supply terminal (+Vs) of the third operational amplifier U3 is used to connect to the +5V power supply, and the ground terminal (-Vs) of the third operational amplifier U3 is grounded.

[0071] Specifically, the eleventh resistor R11 and the first capacitor C1, and the twelfth resistor R12 and the second capacitor C2 together form a two-stage RC filter circuit. The eleventh resistor R11 and the first capacitor C1 form the first stage of filtering, and the twelfth resistor R12 and the second capacitor C2 form the second stage of filtering. This is used to filter the input first dimming signal PWM_Min step by step, filtering out high-frequency ripple and interference in the signal, and outputting a stable first dimming signal PWM_Min, avoiding high-frequency noise affecting the control accuracy. The thirteenth resistor R13 serves as a feedback and signal transmission resistor, used to receive the stable first dimming signal PWM_Min after two stages of RC filtering, and accurately transmit it to the inverting input terminal of the third operational amplifier U3, realizing the effective introduction of the first dimming signal PWM_Min. The fourteenth resistor R14 serves as a sampling signal input resistor, used to receive the first sampling current Imin after being amplified by the first differential amplifier unit 1022, and together with the fifteenth resistor R15, transmits the feedback signal of the first sampling current Imin to the non-inverting input terminal of the third operational amplifier U3, providing current feedback for the third operational amplifier U3. Finally, the third operational amplifier U3 compares the voltages at the inverting input and the non-inverting input, and outputs a corresponding control signal to the adjustment module 105. This drives the adjustment module 105 to adjust the feedback voltage FB of the voltage conversion module 101, thereby achieving closed-loop constant current precise control in the low current range.

[0072] For example, the first power source can be a +5V power supply.

[0073] It should be noted that the first constant current control module 103 also includes C13, C14, C15, C16, C17 and R26, R27. The connection relationships can be found in [reference needed]. Figure 6As shown, C13 and C14 serve as power supply filter capacitors, filtering out high-frequency ripple and interference signals from the +5V power supply to provide a stable and clean operating power supply for the third operational amplifier U3, ensuring the stability and consistency of the operational amplifier's amplification performance. C15 and R26 are connected in series between the output and inverting input of the third operational amplifier U3, forming an RC phase compensation network. This network suppresses potential self-oscillations during operation, optimizes the phase characteristics of the amplifier circuit, improves the stability and response speed of the closed-loop negative feedback, and ensures the output stability of the third operational amplifier U3. C16 is connected between the output and inverting input of the third operational amplifier U3 to further filter out high-frequency noise and signal spikes, smooth the feedback signal waveform, and reduce signal ripple. The effect of dynamics on control accuracy helps improve the stability of closed-loop control; C17 is connected between the non-inverting input of the third operational amplifier U3 and ground, serving as a filter capacitor for the non-inverting input. It can filter out low-frequency interference and residual noise in the current feedback signal of the non-inverting input, ensuring the purity of the input signal and preventing noise from causing the comparison reference of the third operational amplifier U3 to shift, thus ensuring the accuracy of small current regulation; R27 is connected to the output of the third operational amplifier U3 as an output current limiting resistor. It can limit the current output of the third operational amplifier U3 to the adjustment module 105, preventing excessive current from impacting the subsequent adjustment module 105. At the same time, it acts as a buffer signal, optimizing the transmission characteristics of the first control signal and ensuring the reliability of the two-stage constant current control loop switching and operation.

[0074] In one embodiment of this application, such as Figure 7 As shown, the second constant current control module 104 includes a fourth operational amplifier U4, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a third capacitor C3, and a fourth capacitor C4. The first terminal of the sixteenth resistor R16 is used to receive the second dimming signal PWM_Max. The second terminal of the sixteenth resistor R16 is electrically connected to the first terminal of the third capacitor C3 and the first terminal of the seventeenth resistor R17, respectively. The first terminal of the eighteenth resistor R18 is electrically connected to the first terminal of the fourth capacitor C4 and the second terminal of the seventeenth resistor R17, respectively. The two terminals are electrically connected. The second terminal of the eighteenth resistor R18 is electrically connected to the inverting input terminal (-IN) of the fourth operational amplifier U4. The non-inverting input terminal (+IN) of the fourth operational amplifier U4 is electrically connected to the second terminal of the nineteenth resistor R19 and the first terminal of the twentieth resistor R20. The output terminal (OUT) of the fourth operational amplifier U4 is electrically connected to the adjustment module 105. The second terminals of the third capacitor C3 and the fourth capacitor C4 are both grounded. The first terminal of the nineteenth resistor R19 is electrically connected to the current sampling module 102. The second terminal of the twentieth resistor R20 is used to connect to the second power supply. The power supply terminal (+Vs) of the fourth operational amplifier U4 is used to connect to the +5V power supply, and the ground terminal (-Vs) of the fourth operational amplifier U4 is grounded.

[0075] Specifically, the sixteenth resistor R16 and the third capacitor C3, and the seventeenth resistor R17 and the fourth capacitor C4 together form a two-stage RC filter circuit. The sixteenth resistor R16 and the third capacitor C3 are the first-stage filter, and the seventeenth resistor R17 and the fourth capacitor C4 are the second-stage filter. They are used to filter the input second dimming signal PWM_Max step by step, filtering out high-frequency ripple and interference in the signal, and outputting a stable second dimming signal PWM_Max, avoiding high-frequency noise affecting the control accuracy. The eighteenth resistor R18 serves as a feedback and signal transmission resistor, used to receive the stable second dimming signal PWM_Max after two-stage RC filtering, and accurately transmit it to the inverting input of the fourth operational amplifier U4, realizing the effective introduction of the second dimming signal PWM_Max. The nineteenth resistor R19 serves as a sampling signal input resistor, used to receive the second sampling current Imax after being amplified by the second differential amplifier unit 1023, and together with the twentieth resistor R20, transmits the feedback signal of the second sampling current Imax to the non-inverting input of the fourth operational amplifier U4, providing current feedback for the fourth operational amplifier U4. Finally, the fourth operational amplifier U4 compares the voltages at the inverting input and the non-inverting input, and outputs a corresponding control signal to the adjustment module 105. This drives the adjustment module 105 to adjust the feedback voltage FB of the voltage conversion module 101, thereby achieving closed-loop constant current precise control in the high current range.

[0076] For example, the second power source can be a +5V power supply.

[0077] It should be noted that the second constant current control module 104 also includes C18, C19, C20, C21, C22 and R28, R29. The connection relationships can be found in [reference needed]. Figure 7As shown, C18 and C19 serve as power supply filter capacitors, filtering out high-frequency ripple and interference signals from the +5V power supply to provide a stable and clean operating power supply for the fourth operational amplifier U4, ensuring the stability and consistency of the operational amplifier's amplification performance. C20 and R28 are connected in series between the output and inverting input of the fourth operational amplifier U4, forming an RC phase compensation network. This network suppresses potential self-oscillations during operation, optimizes the phase characteristics of the amplifier circuit, improves the stability and response speed of the closed-loop negative feedback, and ensures the output stability of the fourth operational amplifier U4. C21 is connected between the output and inverting input of the fourth operational amplifier U4 to further filter out high-frequency noise and signal spikes, smooth the feedback signal waveform, and reduce signal ripple. The effect of dynamics on control accuracy is mitigated, and the stability of closed-loop control is improved. C22 is connected between the non-inverting input of the fourth operational amplifier U4 and ground as a filter capacitor for the non-inverting input. It can filter out low-frequency interference and residual noise in the current feedback signal of the non-inverting input, ensuring the purity of the input signal and preventing noise from causing the comparison reference of the fourth operational amplifier U4 to shift, thus ensuring the accuracy of high-current regulation. R29 is connected to the output of the fourth operational amplifier U4 as an output current limiting resistor. It can limit the current output of the fourth operational amplifier U4 to the adjustment module 105, preventing excessive current from impacting the subsequent adjustment module 105. At the same time, it acts as a buffer signal, optimizing the transmission characteristics of the second control signal and ensuring the reliability of the two-stage constant current control loop switching and operation.

[0078] In one embodiment of this application, such as Figure 8 As shown, the adjustment module 105 includes a first diode D1, a second diode D2, a twenty-first resistor R21, a twenty-second resistor R22, and a twenty-third resistor R23. The anode of the first diode D1 is electrically connected to the second constant current control module 104 and the first terminal of the twenty-first resistor R21, respectively. The cathode of the first diode D1 is electrically connected to the first constant current control module 103. The first terminal of the twenty-second resistor R22 is electrically connected to the second terminal of the twenty-first resistor R21. The second terminal of the twenty-second resistor R22 is electrically connected to the first terminal of the twenty-third resistor R23. The anode of the second diode D2 is electrically connected to the second terminal of the twenty-third resistor R23. The cathode of the second diode D2 is electrically connected to the voltage conversion module 101.

[0079] Specifically, both the first diode D1 and the second diode D2 serve unidirectional conduction and isolation functions. The first diode D1 enables unidirectional transmission and mutual isolation of the output signals from the first constant current control module 103 and the second constant current control module 104, preventing signal interference during operation of the two control modules and ensuring independence and stability during switching between low and high brightness conditions. The second diode D2 prevents the feedback voltage FB of the voltage conversion module 101 from flowing back to the adjustment module 105, protecting the constant current control module from reverse voltage surges. The twenty-first resistor R21 and the twenty-second resistor R22, along with... The twenty-third resistor R23 is a voltage divider resistor. The three resistors are connected in series to form a signal transmission and voltage divider circuit, which can limit the current output from the two-stage constant current control module to the voltage conversion module 101, and prevent excessive current from damaging the voltage conversion module 101. In addition, by adjusting the resistance ratio, the amplitude of the signal voltage transmitted to the voltage conversion module 101 is adjusted more precisely, thereby achieving fine control of the output voltage of the voltage conversion module 101. Ultimately, this ensures the stable output of the LED light source module 20 current, and together with the two-stage constant current control architecture, achieves a wide range and high precision brightness adjustment effect.

[0080] It should be noted that the adjustment module 105 also includes C23 and C24. C23 is connected to the end of the 21st resistor R21 and can filter out high-frequency ripple and residual interference in the first control signal / second control signal, avoiding noise affecting the adjustment accuracy of the feedback voltage FB and ensuring the stability of signal transmission. C24 is connected to the end of the 22nd resistor R22 and can further filter the signal after voltage division by the 21st resistor R21 and the 22nd resistor R22, filtering out noise and signal fluctuations that may be introduced during the voltage division process, making the signal finally transmitted to the second diode D2 and voltage conversion module 101 purer and more stable, helping to improve the accuracy of the feedback voltage FB adjustment, thereby ensuring the stable output of the LED light source module 20 current and the smoothness of the two-level brightness switching.

[0081] In one embodiment of this application, such as Figure 9 As shown, the voltage conversion module 101 includes a voltage conversion chip. The enable pin of the voltage conversion chip is used to receive the enable signal EN. The input pin of the voltage conversion chip is used to receive the input voltage. The feedback pin of the voltage conversion chip is electrically connected to the adjustment module 105 and is used to receive the feedback voltage FB. The output pin of the voltage conversion chip is used to be electrically connected to the LED light source module 20.

[0082] Specifically, the enable pin is used to control the start and stop of the voltage conversion chip, realizing on-demand start and stop of circuit power supply; the input pin receives the external input voltage, providing the basic power supply for the chip; the feedback pin receives the feedback voltage FB transmitted by the adjustment module 105, senses the current change of the LED light source module 20 in real time, and then dynamically adjusts the output voltage of the voltage conversion chip (i.e., the power supply voltage of the LED light source module 20); the output pin is used to output a stable power supply voltage to power the LED light source module 20, and can accurately adjust the output voltage amplitude according to the change of the feedback voltage FB. With the synergistic effect of the two-stage constant current control loop and the adjustment module 105, a wide range and high precision control of the current of the LED light source module 20 is achieved, ensuring low-brightness low-light output and high-brightness stable operation.

[0083] It should be noted that the voltage conversion chip shown in this embodiment is specifically a buck chip, and its peripheral circuitry consists of matching circuitry devices adapted to the buck chip configuration. In practical applications, other types of voltage conversion chips, such as boost chips or buck-boost chips, can also be selected according to power supply requirements, as long as the selected chip can achieve voltage conversion and output regulation functions, thereby stably providing operating power to the LED light source module 20. Therefore, this application does not limit the internal chip type and the specific configuration of the peripheral circuitry of the voltage conversion module 101.

[0084] It should be noted that the enable signal EN, the first dimming signal PWM_Min, and the second dimming signal PWM_Max mentioned above can all be derived from... Figure 10 The MCU shown is provided.

[0085] It should be noted that, in view of the shortcomings of the existing technology, which requires a separate linear constant current dimming circuit or a dedicated dimming chip after the DC-DC outputs a constant voltage, such as low efficiency, high cost, large PCB (Printed Circuit Board) space occupation, and insufficient power density, this application directly eliminates the need for the additional linear constant current dimming circuit in the traditional solution by designing a constant current control circuit 10 through an operational amplifier. This simplifies the circuit structure and effectively avoids many of the drawbacks of the existing technology.

[0086] The working principle of the constant current control circuit 10 will be described in detail below with reference to the circuit diagram.

[0087] When powered on, the output terminals of the third operational amplifier U3 and the fourth operational amplifier U4 both output a 5V high level. This signal is transmitted through resistors, capacitors and diodes and then fed to the FB pin of the voltage conversion chip. At this time, the output voltage of the voltage conversion chip is at its lowest value. This lowest voltage can be determined by calculating the resistance ratio of the corresponding voltage divider resistors.

[0088] At low brightness, the MCU outputs the first dimming signal PWM_Min (the duty cycle of the second dimming signal PWM_Max is 0%), which is then filtered by an RC filter and transmitted to the inverting input of the third operational amplifier U3. This causes the output of the third operational amplifier U3 to decrease, thereby triggering the first diode D1 to conduct. After the first diode D1 conducts, it diverts some current, resulting in a decrease in the anode voltage of the first diode D1. This voltage is then divided by subsequent resistors and transmitted to the FB pin of the voltage conversion chip, causing a decrease in the voltage at the FB pin. This, in turn, increases the output voltage of the voltage conversion chip, thereby increasing the first current flowing through the LED light source module 20. After passing through sampling resistors (R1 and R2), the first current is amplified 590 times by the first differential amplifier unit 1022 and output to the non-inverting input of the third operational amplifier U3. This forms a closed-loop negative feedback with the first dimming signal PWM_Min at the inverting input, ensuring precise control in the low current range. During this process, since the inverting input of the fourth operational amplifier U4 is not connected to a valid second dimming signal PWM_Max, the fourth operational amplifier U4 is in an open-loop state and continuously outputs a 5V high level. The high-current control loop does not work and will not affect the low-current control loop.

[0089] At high brightness, the MCU outputs the second dimming signal PWM_Max (the duty cycle of the first dimming signal PWM_Min is 100%). After RC filtering, it is transmitted to the inverting input of the fourth operational amplifier U4, causing the output of the fourth operational amplifier U4 to decrease. After being divided by resistors, it is transmitted to the FB pin of the voltage conversion chip, causing the voltage at the FB pin to decrease, which in turn causes the output voltage of the voltage conversion chip to increase, thereby increasing the first current flowing through the LED light source module 20. After passing through the sampling resistors (R1 and R2), the first current is amplified 10 times by the second differential amplifier unit 1023 and then output to the non-inverting input of the fourth operational amplifier U4. This forms a closed-loop negative feedback with the second dimming signal PWM_Max at the inverting input, ensuring stable control in the high current range. During this process, since the non-inverting input of the fourth operational amplifier U4 has a certain voltage value, the duty cycle of the second dimming signal PWM_Max needs to reach a preset value (such as 5%) before the fourth operational amplifier U4 can start working and output the second control signal. After subsequent adjustment, current sampling and amplification, the voltage at the non-inverting input of the third operational amplifier U3 will be greater than the voltage at the inverting input of the third operational amplifier U3, causing the output of the third operational amplifier U3 to output a high level, the first diode D1 to be cut off, at this time the small current control loop stops working, the third operational amplifier U3 is in an open loop state, and will not affect the large current control loop.

[0090] Furthermore, the switching between the two control loops must follow specific logic: when switching from low-current control to high-current control, the duty cycle of the first dimming signal PWM_Min must be adjusted to 100%; when switching from high-current control to low-current control, the duty cycle of the second dimming signal PWM_Max must be adjusted to 0%. The low-current control loop and the high-current control loop are independent working units, ensuring no interference between them. Simultaneously, the above switching logic enables a smooth transition between the two control levels, preventing flashing during the switching process.

[0091] For example, after the first differential amplification unit 1022 differentially amplifies the second current output by the current sampling unit 1021 by a first preset factor (590 times), the amplified output signal can reach 3V, corresponding to a current of 150mA for the LED light source module 20, which is suitable for the precise control requirements under low brightness conditions. After the second differential amplification unit 1023 differentially amplifies the second current by a second preset factor (10 times), the amplified output signal can also reach 3V, corresponding to a current of 8.8A for the LED light source module 20, which meets the requirement of stable output of large current under high brightness conditions. Compared with the existing solutions that can only achieve a minimum current of about 1mA, this application can optimize the minimum operating current of the LED light source module 20 to the tens of μA level through a two-stage differential amplification design, which greatly reduces the dimming start-up point and better adapts to the usage requirements of low-light scenarios.

[0092] This application also discloses a constant current control device, including the aforementioned constant current control circuit 10. By integrating the constant current control circuit 10, the constant current control device can achieve two-level analog dimming and precise constant current control of the LED light source module 20. This significantly reduces the dimming start-up point and optimizes the minimum operating current from about 1mA in existing solutions to the tens of μA level, meeting the stringent requirements for low-brightness accuracy in scenarios such as night scene supplementary lighting, precision instrument indication, and low-light environment monitoring. Furthermore, through differentiated regulation of two independent closed-loop circuits with large and small currents, it improves the adjustment range and control accuracy in the low current range while achieving a stable output of up to 8.8A high current, achieving a wide-range, high-precision brightness adjustment effect and making the light combination more accurate. Meanwhile, this device eliminates the need for linear constant current dimming circuits or dedicated dimming chips in traditional solutions, effectively improving product power density and operating efficiency, reducing heat dissipation pressure, lowering overall cost and PCB layout space, and achieving smooth transition between large and small current loops through optimized switching logic to avoid flashing. It also eliminates the need for complex software control, saving software resources and can flexibly adapt to the application needs of different fields such as LED lights and photographic lights, significantly enhancing product reliability and market competitiveness.

[0093] Since the processing and functions implemented by the constant current control device in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned constant current control circuit, any details not covered in this embodiment can be found in the relevant descriptions in the aforementioned embodiments, and will not be repeated here.

[0094] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A constant current control circuit (10), characterized in that, It includes a voltage conversion module (101), a current sampling module (102), a first constant current control module (103), a second constant current control module (104), and an adjustment module (105), wherein: The current sampling module (102) is used to collect the first current flowing through the LED light source module (20), and is electrically connected to the first constant current control module (103) and the second constant current control module (104) respectively. The current sampling module (102) outputs a first sampling current to the first constant current control module (103) and a second sampling current to the second constant current control module (104) according to the first current. The current sampling module (102) includes a current sampling unit (1021), a first differential amplification unit (1022), and a second differential amplification unit (1023), wherein: The current sampling unit (1021) is electrically connected to the first differential amplifier unit (1022) and the second differential amplifier unit (1023) respectively. The current sampling unit (1021) is used to collect the first current flowing through the LED light source module (20) and output the second current to the first differential amplifier unit (1022) and the second differential amplifier unit (1023) respectively. The first differential amplifier unit (1022) is electrically connected to the first constant current control module (103). The first differential amplifier unit (1022) is used to amplify the second current by a first preset factor to obtain the first sampling current, and transmit the first sampling current to the first constant current control module (103). The second differential amplifier unit (1023) is electrically connected to the second constant current control module (104). The second differential amplifier unit (1023) is used to amplify the second current by a second preset factor to obtain the second sampling current, and transmit the second sampling current to the second constant current control module (104). The first constant current control module (103) is used to receive the first dimming signal and generate a first control signal based on the first sampling current and the first dimming signal; The second constant current control module (104) is used to receive the second dimming signal and generate a second control signal based on the second sampling current and the second dimming signal; The adjustment module (105) is electrically connected to the voltage conversion module (101), the first constant current control module (103) and the second constant current control module (104) respectively. The adjustment module (105) is used to adjust the feedback voltage of the voltage conversion module (101) according to the first control signal or the second control signal. The first constant current control module (103) and the second constant current control module (104) form mutually independent closed-loop constant current control loops, and the two closed-loop constant current control loops work mutually exclusively to form closed-loop constant current control in different brightness ranges respectively.

2. The constant current control circuit (10) according to claim 1, characterized in that, The first preset multiple is greater than the second preset multiple.

3. The constant current control circuit (10) according to claim 1, characterized in that, The current sampling unit (1021) includes a first resistor and a second resistor. The first end of the first resistor and the first end of the second resistor are respectively electrically connected to the first differential amplifier unit (1022) and the second differential amplifier unit (1023). The first end of the first resistor and the first end of the second resistor are both used to be electrically connected to the LED light source module (20). The second end of the first resistor and the second end of the second resistor are both grounded.

4. The constant current control circuit (10) according to claim 1, characterized in that, The first differential amplifier unit (1022) includes a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The non-inverting input terminal of the first operational amplifier is electrically connected to the second terminal of the fourth resistor and the first terminal of the fifth resistor, respectively. The inverting input terminal of the first operational amplifier is electrically connected to the second terminal of the third resistor and the first terminal of the sixth resistor, respectively. The output terminal of the first operational amplifier is electrically connected to the second terminal of the sixth resistor and the first constant current control module (103), respectively. The first terminal of the third resistor and the second terminal of the fifth resistor are both grounded. The first terminal of the fourth resistor is electrically connected to the current sampling unit (1021).

5. The constant current control circuit (10) according to claim 1, characterized in that, The second differential amplifier unit (1023) includes a second operational amplifier, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor. The non-inverting input terminal of the second operational amplifier is electrically connected to the second terminal of the eighth resistor and the first terminal of the ninth resistor, respectively. The inverting input terminal of the second operational amplifier is electrically connected to the second terminal of the seventh resistor and the first terminal of the tenth resistor, respectively. The output terminal of the second operational amplifier is electrically connected to the second terminal of the tenth resistor and the second constant current control module (104), respectively. The first terminal of the seventh resistor and the second terminal of the ninth resistor are both grounded. The first terminal of the eighth resistor is electrically connected to the current sampling unit (1021).

6. The constant current control circuit (10) according to claim 1, characterized in that, The first constant current control module (103) includes a third operational amplifier, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a first capacitor, and a second capacitor. The first end of the eleventh resistor is used to receive the first dimming signal. The second end of the eleventh resistor is electrically connected to the first end of the first capacitor and the first end of the twelfth resistor. The first end of the thirteenth resistor is electrically connected to the first end of the second capacitor and the second end of the twelfth resistor. The second end of the thirteenth resistor is electrically connected to the inverting input of the third operational amplifier. The non-inverting input of the third operational amplifier is electrically connected to the second end of the fourteenth resistor and the first end of the fifteenth resistor. The output of the third operational amplifier is electrically connected to the adjustment module (105). The second ends of the first capacitor and the second capacitor are both grounded. The first end of the fourteenth resistor is electrically connected to the current sampling module (102). The second end of the fifteenth resistor is used to be electrically connected to the first power supply.

7. The constant current control circuit (10) according to claim 1, characterized in that, The second constant current control module (104) includes a fourth operational amplifier, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a third capacitor, and a fourth capacitor. The first end of the sixteenth resistor is used to receive the second dimming signal. The second end of the sixteenth resistor is electrically connected to the first end of the third capacitor and the first end of the seventeenth resistor. The first end of the eighteenth resistor is electrically connected to the first end of the fourth capacitor and the second end of the seventeenth resistor. The second end of the eighteenth resistor is electrically connected to the inverting input of the fourth operational amplifier. The non-inverting input of the fourth operational amplifier is electrically connected to the second end of the nineteenth resistor and the first end of the twentieth resistor. The output of the fourth operational amplifier is electrically connected to the adjustment module (105). The second ends of the third capacitor and the fourth capacitor are both grounded. The first end of the nineteenth resistor is electrically connected to the current sampling module (102). The second end of the twentieth resistor is used to be electrically connected to the second power supply.

8. The constant current control circuit (10) according to claim 1, characterized in that, The adjustment module (105) includes a first diode, a second diode, a twenty-first resistor, a twenty-second resistor, and a twenty-third resistor. The anode of the first diode is electrically connected to the first terminal of the second constant current control module (104) and the second terminal of the second eleventh resistor, respectively. The cathode of the first diode is electrically connected to the first constant current control module (103). The first terminal of the second twelfth resistor is electrically connected to the second terminal of the second eleventh resistor. The second terminal of the second twelfth resistor is electrically connected to the first terminal of the second thirteenth resistor. The anode of the second diode is electrically connected to the second terminal of the second thirteenth resistor. The cathode of the second diode is electrically connected to the voltage conversion module (101).

9. The constant current control circuit (10) according to any one of claims 1-8, characterized in that, The voltage conversion module (101) includes a voltage conversion chip. The enable pin of the voltage conversion chip is used to receive an enable signal. The input pin of the voltage conversion chip is used to receive an input voltage. The feedback pin of the voltage conversion chip is electrically connected to the adjustment module (105) to receive the feedback voltage. The output pin of the voltage conversion chip is used to be electrically connected to the LED light source module (20).

10. A constant current control device, characterized in that, Includes the constant current control circuit (10) as described in any one of claims 1-9.

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