Multi-channel LED brightness equalization and power consumption control circuit

Abstract

The utility model relates to electronic technical field especially, and it is more road LED luminance equalization and power consumption control circuit, including total constant current source module, total power consumption control module, current mirror array module and at least two LED branch, the output of total constant current source module is connected with the input of total power consumption control module, is used for providing stable total reference current, the output of total power consumption control module is connected to the public power supply end of current mirror array module, current mirror array module includes the same current mirror unit as the number of LED branch, and the output of each current mirror unit independently connects an LED branch, LED branch includes LED unit and precision sampling resistance, and LED unit and precision sampling resistance are connected in series and constitute current loop, the utility model discloses adopting common source common gate current mirror array as the distribution core, realizes the high accuracy luminance equalization of more road LED, adopts the simple module that a single MOS tube works in linear area and the voltage limiting resistance constitutes, realizes the adaptive restriction of system total power consumption.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a multi-channel LED brightness equalization and power consumption control circuit. Background Technology

[0002] LED lighting systems are widely used in displays, backlighting, and general lighting. In practical applications, multiple LED lights are often connected in series and parallel to achieve higher light output or a more uniform light field distribution. However, due to the manufacturing tolerances and temperature drift of forward voltage drop inherent in LED devices, even if the same driving voltage is applied to each branch, the current flowing through each light will be mismatched, resulting in severe brightness unevenness and affecting overall luminous efficacy and product quality.

[0003] To achieve current balancing for multiple LEDs, existing technologies typically employ the following approaches: The first approach involves connecting a current-limiting resistor in series with each LED. While this method has a simple circuit structure, it cannot compensate for current differences caused by the discreteness of LED parameters. The second approach involves configuring an independent constant current source circuit for each LED. Although this method can improve current stability, the constant current sources are independent of each other, making it impossible to achieve total power consumption management.

[0004] Therefore, it is necessary to further improve the multi-channel LED brightness equalization and power consumption control circuit. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the existing defects and provide a multi-channel LED brightness equalization and power consumption control circuit. It adopts a common source common gate current mirror array as the distribution core to achieve high-precision brightness equalization of multiple LEDs. It uses a simple module consisting of a single MOS transistor operating in the linear region and a voltage limiting resistor to achieve adaptive limitation of the total power consumption of the system, which can effectively solve the problems in the background technology.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a multi-channel LED brightness equalization and power consumption control circuit, including a total constant current source module, a total power consumption control module, a current mirror array module, and at least two LED branches;

[0007] The output terminal of the total constant current source module is connected to the input terminal of the total power consumption control module to provide a stable total reference current;

[0008] The output of the total power consumption control module is connected to the common power supply terminal of the current mirror array module;

[0009] The current mirror array module includes the same number of current mirror units as the number of LED branches, and the output of each current mirror unit is independently connected to an LED branch.

[0010] The LED branch includes an LED unit and a precision sampling resistor, with the LED unit and the precision sampling resistor connected in series to form a current loop.

[0011] Preferably, the total power consumption control module includes a power consumption control MOSFET and a voltage limiting resistor;

[0012] The source of the power-controlled MOSFET serves as the input terminal of the total power-power control module and is connected to the output terminal of the total constant current source module; its drain serves as the output terminal of the total power-power control module and is connected to the common power supply terminal of the current mirror array module; its gate is grounded through a voltage-limiting resistor.

[0013] By selecting the resistance value of the voltage-limiting resistor, the gate-source voltage of the power-dissipating control MOSFET is set to operate in the linear region, thereby limiting the total system power consumption of the circuit to below a preset value.

[0014] Preferably, each of the current mirror units includes a bottom-layer mirror MOSFET and a top-layer high-impedance load MOSFET;

[0015] The sources of the bottom-level mirror MOS transistors in each current mirror unit are grounded, and their gates are interconnected to serve as the current reference input terminal of the current mirror array module. This input terminal is connected to the output terminal of the total constant current source module.

[0016] The source of the top-level high-impedance load MOSFET of each current mirror unit is connected to the drain of the corresponding bottom-level mirror MOSFET. After the gates are interconnected, they are connected to the common power supply terminal of the current mirror array module and the output terminal of the total power consumption control module. Their drains are used as the output terminals of each current mirror unit to drive the corresponding LED branch.

[0017] Preferably, the total constant current source module includes a bottom constant current MOSFET and a top constant current MOSFET;

[0018] The source of the underlying constant current MOS transistor is grounded, and its gate is connected to the reference current source.

[0019] The source of the top-level constant current MOSFET is connected to the drain of the bottom-level constant current MOSFET, its gate is connected to a constant bias voltage, and its drain serves as the output terminal of the total constant current source module and is connected to the input terminal of the total power consumption control module.

[0020] Preferably, the voltage-limiting resistor is an adjustable resistor.

[0021] Preferably, a filter capacitor is connected in parallel between the gate of the power control MOS transistor and ground to eliminate gate noise interference; a compensation capacitor is connected in parallel across each of the precision sampling resistors to suppress high-frequency oscillations.

[0022] Preferably, the total constant current source module includes an enable control unit connected between the gate of the underlying constant current MOS transistor and the reference current source;

[0023] The enable control unit includes an enable control MOSFET and a pull-up resistor;

[0024] The drain of the enable control MOS transistor is connected to the reference current source, and its source is connected to the gate of the underlying constant current MOS transistor. Its gate serves as the enable terminal of the total constant current source module, and a pull-up resistor is connected between the gate of the enable control MOS transistor and the positive power supply.

[0025] Compared with the prior art, the beneficial effects of this utility model are:

[0026] Using a common-source cascode current mirror array as the distribution core, its high output impedance characteristics effectively resist the influence of the difference in forward voltage of each LED, ensuring the high consistency of the current of multiple LEDs from the perspective of pure circuit structure, and overcoming the problem of uneven brightness caused by the dispersion of device parameters.

[0027] A simple module consisting of a single MOSFET operating in the linear region and a voltage-limiting resistor is used to achieve adaptive clamping of the total system power consumption in pure hardware. This structure does not require feedback circuitry and can automatically limit the total power consumption when the input voltage fluctuates or the load changes. The circuit is simple and low in cost.

[0028] Each functional module is physically integrated through an optimized PCB layout. Combined with symmetrical wiring and filtering compensation measures, it improves anti-interference capability and stability, and facilitates production and maintenance. Integration enables the control unit to achieve more intelligent management. Attached Figure Description

[0029] Figure 1 This is a circuit structure block diagram of the present invention;

[0030] Figure 2 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0031] 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 can 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.

[0032] It should be understood that, when used in this 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 sets.

[0033] To keep the drawings concise, only the parts relevant to this invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0034] It should also be further 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.

[0035] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0037] Please see Figure 1-2 This utility model provides a technical solution: a multi-channel LED brightness equalization and power consumption control circuit. In practical use, this utility model can be used as a unit module and can be cascaded and expanded by connecting its respective enable control unit.

[0038] Figure 1 The overall circuit structure block diagram of this utility model is shown. The system consists of a total constant current source module, a total power consumption control module, a current mirror array module, and multiple cascaded LED branches from top to bottom. The flow of electrical energy and control signals is as follows: the total constant current source module generates a stable total reference current, which flows through the total power consumption control module. This module monitors and limits the total power consumption of the system while transmitting the current. Subsequently, the current enters the common power supply terminal of the current mirror array module and is precisely mirrored and distributed to each LED branch, ultimately driving all LEDs to emit light. It should be noted that the above-mentioned circuit modules and their connection relationships are physically implemented through the wiring layout and component mounting structure of the printed circuit board (PCB).

[0039] Figure 2 The circuit schematic of a multi-channel LED brightness equalization and power consumption control circuit is shown. The following will describe the circuit's workflow. Figure 2 The illustrated embodiments are described step by step.

[0040] The normal operation of this circuit begins with the establishment of the total constant current source module. The core function of this module is to generate a stable reference current that is unaffected by power supply voltage fluctuations; such as Figure 2 As shown, a preferred embodiment of this module includes a bottom-layer constant current MOSFET Q1 and a top-layer constant current MOSFET Q2.

[0041] The source of the bottom constant current MOSFET Q1 is grounded, and its gate receives a current I_REF from an external reference current source. This reference current source can be a resistor and a voltage source connected in series. When I_REF flows into the gate of Q1, a voltage will be generated between the gate and source of Q1. According to the saturation current formula of the MOSFET, the drain current of Q1 is a fixed value related to I_REF.

[0042] The source of the top-level constant current MOSFET Q2 is connected to the drain of Q1, and its gate is connected to a constant bias voltage V_BIAS. This constant bias voltage can be obtained from the system power supply by a simple resistor voltage divider network and generated after being filtered by a capacitor. Its drain serves as the output terminal of the total constant current source module. Q1 and Q2 together form a common source and common gate structure. The main function of Q2 is to significantly increase the output impedance of the total constant current source module.

[0043] After power-on, the reference current source starts working, providing a current I_REF to the gate of Q1. Q1 turns on under the action of I_REF and establishes a defined drain current. This current flows through Q2. Since the gate of Q2 is biased by a stable V_BIAS, it acts as a high-impedance load, effectively isolating the voltage fluctuations of the subsequent total power consumption control module from affecting the operating state of Q1. Finally, a stable total reference current is output at the drain of Q2, and this current value is approximately equal to I_REF.

[0044] The current output from the total constant current source module enters the total power consumption control module; this module is used to ensure that the total power consumption of the system does not exceed the preset safety value; the source of the power control MOSFET Q3 is connected to the output of the total constant current source module, i.e., the drain of Q2; its drain is connected to the current mirror array module of the subsequent stage; its gate voltage is set by the voltage limiting resistor R_set. This MOSFET is designed to operate in the linear region, rather than in a completely switching state.

[0045] The voltage limiting resistor R_set is set between the gate of the power-consuming control MOSFET Q3 and ground. Its resistance value determines the current flowing through the gate of Q3, thereby setting the gate-to-ground voltage of Q3. Since the source voltage of Q3 is very low and close to the saturation voltage drop of Q2, the gate-to-ground voltage of Q3 basically determines the gate-source voltage of Q3. In this embodiment, R_set can be an adjustable resistor, which is convenient for flexible adjustment in production or use.

[0046] The filter capacitor C_g is connected in parallel across R_set to filter out high-frequency noise that may couple to the gate of Q3 from the power supply or other sources, preventing malfunctions and improving system stability.

[0047] During the design, based on the maximum allowable total power consumption, the required gate-source voltage of Q3 is derived by using the power consumption formula and the characteristics of the MOSFET, and the resistance value of R_set is selected accordingly. Under normal operating conditions, the output voltage V_supply of the total constant current source module is moderate, and the voltage V_array required by the current mirror array is also normal. At this time, the drain-source voltage of Q3 is small, it operates at the edge of the linear region, its on-resistance is very small, and its own power consumption is very low.

[0048] The power limiting function of this module will be activated under the following two conditions;

[0049] In scenario one, the output voltage V_supply of the constant current source module increases. Without a total power consumption control module, V_array would increase accordingly, leading to a linear increase in total power consumption. However, in this circuit, the increase in V_supply attempts to raise the drain voltage of the power consumption control MOSFET Q3. But since the total current is fixed by the constant current source, the drain-source voltage of Q3 will increase. Because the gate-source voltage of Q3 is fixed by the voltage-limiting resistor R_set, according to the output characteristics of the MOSFET, when the drain-source voltage increases to a certain extent, Q3 will enter the deep part of the linear region, and its equivalent resistance will increase rapidly. This will consume most of the increment of V_supply on its own voltage drop drain-source voltage, preventing a significant increase in V_array and maintaining the basic stability of total power consumption.

[0050] Scenario 2: An LED branch is open-circuited. When an LED is open-circuited due to a fault, the current in that LED branch is zero, the total load of the current mirror array is reduced, and the voltage V_array required for its normal operation will decrease. This will also cause the drain-source voltage of the power control MOSFET Q3 to increase, triggering the same power limiting mechanism as in Scenario 1.

[0051] The output current of the total power consumption control module is fed into the common power supply terminal of the current mirror array module. As a path for a large current to flow, the PCB uses widened and tinned copper foil traces to reduce line impedance and voltage drop. The current mirror array module is used to use the feed current as a reference for precise mirroring and distribution, so that each LED branch obtains an output current that is in a fixed proportion to the reference current.

[0052] The current mirror array module includes current mirror units equal to the number of LED branches. Each current mirror unit includes a bottom-layer mirror MOSFET and a top-layer high-impedance load MOSFET.

[0053] In this embodiment, Q4, Q5, and Q6 are taken as examples of the bottom-level mirror MOSFETs of each current mirror unit. The number of these MOSFETs is equal to that of the LED branches. The sources of Q4, Q5, and Q6 are all grounded, and their gates are all connected together and connected to the output terminal of the total constant current source module to form the input arm of the current mirror. All bottom-level mirror MOSFETs have the same width-to-length ratio to ensure the accuracy of current matching.

[0054] In this embodiment, Q7, Q8, and Q9 are taken as examples of the top-level high-impedance load MOSFETs of each current mirror unit. These MOSFETs correspond one-to-one with the bottom-level mirror MOSFETs and are placed in a symmetrical and closely adjacent manner on the PCB layout, while maintaining the consistency of their drive trace length and width. The source of each top-level high-impedance load MOSFET is connected to the drain of the corresponding bottom-level mirror MOSFET, and all the gates are connected together and connected to the output terminal of the total power consumption control module. The voltage V_array constitutes a common source and common gate structure.

[0055] like Figure 2 As shown, the output current of the total power consumption control module flows into the first current mirror unit composed of Q7 and Q4; since the gates of all the bottom mirror MOSFETs are connected in parallel, they will mirror the current of Q4.

[0056] The high-impedance load MOSFET at the top of the common-source cascode structure increases the output impedance; high output impedance means that the output current of each mirror unit is less sensitive to changes in its output voltage (i.e., the LED anode voltage).

[0057] Because the forward voltages of each LED unit (LED1, LED2, LED3) have manufacturing tolerances and temperature drift, their anode voltages will be different. Traditional current mirror circuits will therefore produce serious current mismatch. The current mirror structure adopted in this invention has a high output impedance that can effectively resist the influence of this forward voltage difference, ensuring that the current flowing through each LED branch is strictly equal to the current value of its mirror image, thereby achieving good brightness uniformity.

[0058] The total constant current source module, total power consumption control module, and current mirror array module of this utility model are respectively concentrated in different physical areas on the PCB, and are implemented through copper foil traces on the PCB as shown in the attached figure. Figure 2 The electrical connections are shown; this physical partitioning layout makes the circuit structure clear and facilitates debugging and maintenance.

[0059] The output of each current mirror unit of the current mirror array module is independently connected to an LED branch, and current flows into each LED branch.

[0060] The LED unit, as the main light source, can be selected from various types and materials of LEDs, such as white LEDs and high-brightness RGB LEDs.

[0061] Precision sampling resistors R1, R2, and R3 are connected in series between the cathode and ground of each LED unit in each LED branch. Their resistance is very small, and their main function is not current limiting, but to provide a voltage signal for fault detection or fine-tuning. By measuring the voltage across them, the actual current of the branch can be accurately determined.

[0062] Compensation capacitors C1, C2, and C3 are optional capacitors connected in parallel across each precision sampling resistor. They are used to form a low-pass filter with the parasitic inductance of the line, suppressing high-frequency oscillations that may be caused by long conductors or PCB layout, and ensuring the stability of the current in each branch.

[0063] In this invention, the filter capacitor C_g and the compensation capacitors C1, C2, and C3 of each LED branch are all placed close to the pins of their filter components on the PCB layout, and are directly connected to the ground plane through vias to form a filter network with the shortest possible loop.

[0064] The current output from the current mirror array drives the LED unit to emit light and flows through the precision sampling resistor, generating a voltage drop proportional to the current; the entire loop is closed, and the system enters a stable operating state; maintenance personnel can easily diagnose whether any branch has an open circuit or short circuit fault by measuring the voltage across the sampling resistor.

[0065] To make the circuit more intelligent, this utility model integrates an enable control unit in the main constant current source module; wherein the enable control MOS transistor Q10 has its drain connected to the reference current source I_REF, its source connected to the gate of the underlying constant current MOS transistor Q1, and its gate serves as the enable terminal EN.

[0066] Pull-up resistor R4 is connected between the gate of Q1 and the positive power supply. When the enable terminal EN is set to a high level by an external circuit such as the GPIO of the MCU, Q10 is turned on. The pull-up resistor R4 pulls the gate voltage of Q1 up to the power supply voltage, making the gate-source voltage of Q1 zero, ensuring that Q1 is reliably turned off, thereby cutting off the total current of the entire circuit.

[0067] The working principle of this utility model is as follows:

[0068] The constant current source modules Q1 and Q2, which utilize a common source and common gate structure, generate a highly stable total reference current that is unaffected by power supply voltage fluctuations. Through a simplified closed loop formed by the power MOSFET Q3 operating in the linear region and the voltage limiting resistor R_set, the physical characteristic that the equivalent resistance of the MOSFET in the linear region automatically changes with the drain-source voltage is utilized to achieve hardware adaptive limitation of the total power consumption of the system. When the input voltage increases or the load decreases, causing the system to tend to over-power consumption, this module maintains the stability of the total power consumption by increasing its own voltage drop.

[0069] The system employs a common-source cascode current mirror structure with high output impedance. By utilizing the characteristic that the output current is insensitive to changes in output voltage, it overcomes the current mismatch caused by the difference in forward voltage of each LED unit and achieves high-precision balanced distribution of multi-channel output current. Each LED branch provides a current monitoring point while performing the light-emitting function through a series precision sampling resistor, which facilitates system status diagnosis.

[0070] The working principle of this utility model is as follows:

[0071] The three core functional modules—total constant current source, total power consumption control, and current mirror array—are physically partitioned and laid out on the PCB. Electrical connections are achieved through standardized copper foil traces, resulting in a clear circuit structure that facilitates production debugging and maintenance.

[0072] By adjusting the resistance value of a single component, such as the voltage-limiting resistor R_set, the maximum safe operating power consumption of the system can be preset, giving the circuit programmable characteristics without increasing complexity.

[0073] At key nodes such as the gate of the power control MOS transistor and the sampling resistors of each branch, a layout principle of connecting capacitors in parallel as close as possible is adopted to effectively suppress high-frequency noise and oscillation, and ensure the stable operation of the system in different environments.

[0074] The integrated enable control units Q10 and R4 enable remote control of the entire system's operating status via a single digital signal EN, facilitating integration into larger management systems and achieving zero-power standby.

[0075] Finally, it should be noted that the above 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A multi-channel LED brightness equalization and power consumption control circuit, characterized in that, Includes a total constant current source module, a total power consumption control module, a current mirror array module, and at least two LED branches; The output terminal of the total constant current source module is connected to the input terminal of the total power consumption control module to provide a stable total reference current; The output of the total power consumption control module is connected to the common power supply terminal of the current mirror array module; The current mirror array module includes the same number of current mirror units as the number of LED branches, and the output of each current mirror unit is independently connected to an LED branch. The LED branch includes an LED unit and a precision sampling resistor, with the LED unit and the precision sampling resistor connected in series to form a current loop.

2. The multi-channel LED brightness equalization and power consumption control circuit according to claim 1, characterized in that: The total power consumption control module includes a power consumption control MOSFET and a voltage limiting resistor; The source of the power-controlled MOSFET serves as the input terminal of the total power-power control module and is connected to the output terminal of the total constant current source module; its drain serves as the output terminal of the total power-power control module and is connected to the common power supply terminal of the current mirror array module. Its gate is grounded through a voltage-limiting resistor; By selecting the resistance value of the voltage-limiting resistor, the gate-source voltage of the power-dissipating control MOSFET is set to operate in the linear region, thereby limiting the total system power consumption of the circuit to below a preset value.

3. The multi-channel LED brightness equalization and power consumption control circuit according to claim 2, characterized in that: Each current mirror unit includes a bottom-layer mirror MOSFET and a top-layer high-impedance load MOSFET. The sources of the bottom-level mirror MOS transistors in each current mirror unit are grounded, and their gates are interconnected to serve as the current reference input terminal of the current mirror array module. This input terminal is connected to the output terminal of the total constant current source module. The source of the top-level high-impedance load MOSFET of each current mirror unit is connected to the drain of the corresponding bottom-level mirror MOSFET. After the gates are interconnected, they are connected to the common power supply terminal of the current mirror array module and the output terminal of the total power consumption control module. Their drains are used as the output terminals of each current mirror unit to drive the corresponding LED branch.

4. The multi-channel LED brightness equalization and power consumption control circuit according to claim 3, characterized in that: The total constant current source module includes a bottom constant current MOSFET and a top constant current MOSFET; The source of the underlying constant current MOS transistor is grounded, and its gate is connected to the reference current source. The source of the top-level constant current MOSFET is connected to the drain of the bottom-level constant current MOSFET, its gate is connected to a constant bias voltage, and its drain serves as the output terminal of the total constant current source module and is connected to the input terminal of the total power consumption control module.

5. The multi-channel LED brightness equalization and power consumption control circuit according to claim 2, characterized in that: The voltage-limiting resistor is an adjustable resistor.

6. The multi-channel LED brightness equalization and power consumption control circuit according to claim 2, characterized in that: A filter capacitor is connected in parallel between the gate and ground of the power control MOS transistor to eliminate gate noise interference; a compensation capacitor is connected in parallel across the two ends of each precision sampling resistor to suppress high-frequency oscillation.

7. The multi-channel LED brightness equalization and power consumption control circuit according to claim 4, characterized in that: The total constant current source module includes an enable control unit connected between the gate of the underlying constant current MOS transistor and the reference current source. The enable control unit includes an enable control MOSFET and a pull-up resistor; The drain of the enable control MOS transistor is connected to the reference current source, and its source is connected to the gate of the underlying constant current MOS transistor. Its gate serves as the enable terminal of the total constant current source module, and a pull-up resistor is connected between the gate of the enable control MOS transistor and the positive power supply.

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