Feedback regulation circuit and LED driving circuit

Abstract

The application is suitable for the technical field of LED driving, and provides a feedback adjusting circuit and an LED driving circuit.The feedback adjusting circuit comprises a current adjusting module, a pull-up module and a feedback module, the current adjusting module is electrically connected with the pull-up module and the feedback module respectively, the current adjusting module is used for being electrically connected with the negative electrode of an LED load, the feedback module is used for being electrically connected with the input end of a power supply chip, and the output end of the power supply chip is electrically connected with the positive electrode of the LED load.The feedback adjusting circuit is constructed by the independent current adjusting module, the pull-up module and the feedback module in the embodiment of the application, the control is realized without using the mode that the step-down / step-up power supply and the constant current driving control circuit are highly integrated in the same chip, the cost of the feedback adjusting circuit is significantly reduced, the requirement for the integration degree of the power supply chip is reduced, and thus the manufacturing cost of the power supply chip and the design cost of the LED driving circuit are effectively reduced.

Description

Technical Field

[0001] This application belongs to the field of LED driver technology, and in particular relates to a feedback regulation circuit and an LED driver circuit. Background Technology

[0002] Because LEDs (Light Emitting Diodes) need to operate within a suitable voltage and current range, the voltage drop difference between the constant voltage power supply and the LED when powered by a conventional constant voltage source chip can cause significant losses in the drive loop. Therefore, DC constant voltage power supplies such as batteries are not suitable for directly driving LEDs. Currently, most LED driver chip solutions on the market are based on DC-DC conversion circuits and current feedback power management systems. Their working principle involves collecting the LED's operating current through a sensing resistor, converting the current into voltage, and then feeding this voltage back to the chip. The chip maintains a constant output current by adjusting the PWM (Pulse Width Modulation) duty cycle to form a voltage loop negative feedback. For ease of control, the buck-boost power supply and constant current drive control circuit need to be integrated into the same chip. However, due to the highly integrated design of the chip, its manufacturing cost is relatively high, resulting in a high design cost for the LED driver circuit. Utility Model Content

[0003] This application provides a feedback adjustment circuit and an LED driver circuit, which can solve the problem that the design cost of LED driver circuits is high due to the use of expensive integrated chips.

[0004] In a first aspect, embodiments of this application provide a feedback regulation circuit, including a current regulation module, a pull-up module, and a feedback module. The current regulation module is electrically connected to the pull-up module and the feedback module, respectively. The current regulation module is used to be electrically connected to the negative terminal of the LED load, the feedback module is used to be electrically connected to the input terminal of the power chip, and the output terminal of the power chip is electrically connected to the positive terminal of the LED load.

[0005] The pull-up module is used to output a first current, and the current regulation module is used to regulate the second current flowing into the feedback module according to the voltage of the negative terminal of the LED load. The second current is the difference between the first current and the current flowing through the current regulation module. The feedback module is used to output a feedback current to the input terminal of the power chip according to the second current and the reference voltage. The feedback current is used to instruct the power chip to adjust the voltage at the output terminal of the power chip.

[0006] In one possible implementation of the first aspect, the current regulation module includes a first diode, the anode of which is electrically connected to both the pull-up module and the feedback module, and the cathode of which is electrically connected to the negative terminal of the LED load.

[0007] In one possible implementation of the first aspect, the pull-up module includes a first resistor, a first end of which is electrically connected to a first power supply, and a second end of which is electrically connected to the current regulation module and the feedback module, respectively.

[0008] In one possible implementation of the first aspect, the feedback module includes a feedback unit and a unidirectional conduction unit, wherein the feedback unit is electrically connected to the pull-up module, the current regulation module and the unidirectional conduction unit respectively, and the unidirectional conduction unit is used to be electrically connected to the input terminal of the power chip.

[0009] The feedback unit is used to receive the second current and the reference voltage, and output a third current to the unidirectional conduction unit according to the second current and the reference voltage. The unidirectional conduction unit is used to output the feedback current to the power chip according to the third current.

[0010] In one possible implementation of the first aspect, the feedback unit includes a first transistor, a second resistor, and a third resistor. The first end of the second resistor is electrically connected to the current regulation module and the pull-up module, respectively. The second end of the second resistor is electrically connected to the emitter of the first transistor. The collector of the first transistor is electrically connected to the first end of the third resistor. The base of the first transistor is used to receive the reference voltage. The second end of the third resistor is electrically connected to the unidirectional conduction unit.

[0011] In one possible implementation of the first aspect, the feedback unit further includes a fourth resistor, the first end of which is electrically connected to the base of the first transistor, and the second end of which is used to receive the reference voltage.

[0012] In one possible implementation of the first aspect, the unidirectional conduction unit includes a second diode, the anode of which is electrically connected to the feedback unit, and the cathode of which is electrically connected to the power chip.

[0013] In one possible implementation of the first aspect, the feedback adjustment circuit further includes a reference module electrically connected to the feedback module for outputting the reference voltage to the feedback module.

[0014] In one possible implementation of the first aspect, the reference module includes a fifth resistor and a sixth resistor, a first terminal of the fifth resistor is electrically connected to a first reference power supply, a second terminal of the fifth resistor is electrically connected to the first terminal of the sixth resistor and the feedback module, and the second terminal of the sixth resistor is grounded.

[0015] Secondly, embodiments of this application provide an LED driving circuit, including an LED load, a power chip, and a feedback regulation circuit as described in any one of the first aspects. The positive terminal of the LED load is electrically connected to the output terminal of the power chip, the negative terminal of the LED load is electrically connected to the current regulation module in the feedback regulation circuit, and the input terminal of the power chip is electrically connected to the feedback module in the feedback regulation circuit.

[0016] The beneficial effects of the embodiments in this application compared with the prior art are:

[0017] The feedback regulation circuit provided in this application includes a current regulation module, a pull-up module, and a feedback module. The current regulation module is directly connected to the negative terminal of the LED load, enabling it to quickly and accurately detect the operating state of the LED load and the voltage of its negative terminal, and dynamically adjust the second current flowing into the feedback module based on the voltage of the negative terminal of the LED load. The feedback module outputs a feedback current to the input terminal of the power chip based on the received second current and the reference voltage. Since the output terminal of the power chip is connected to the positive terminal of the LED load, after receiving the feedback current output by the feedback module, the power chip can adjust the voltage at its output terminal in real time based on the feedback current, that is, it can adjust the voltage of the positive terminal of the LED load in real time, thereby forming a complete negative feedback control loop. Therefore, this application embodiment constructs a feedback regulation circuit using independent current regulation modules, pull-up modules, and feedback modules, eliminating the need to highly integrate the buck-boost power supply and constant current drive control circuit onto the same chip. This significantly reduces the cost of the feedback regulation circuit and lowers the integration requirements of the power chip, thereby effectively reducing the manufacturing cost of the power chip and the design cost of the LED driver circuit.

[0018] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a schematic block diagram of a feedback adjustment circuit provided in one embodiment of this application;

[0021] Figure 2 This is a circuit connection diagram of a feedback adjustment circuit provided in an embodiment of this application;

[0022] Figure 3 This is a circuit connection diagram of an LED driving circuit provided in an embodiment of this application.

[0023] In the diagram: 10, feedback regulation circuit; 101, current regulation module; 102, pull-up module; 103, feedback module; 1031, feedback unit; 1032, unidirectional conduction unit; 104, reference module. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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]."

[0028] 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.

[0029] 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.

[0030] Currently, most LED driver chip solutions on the market are based on DC-DC converter circuits and current feedback power management systems. Their working principle involves collecting the LED's operating current through a sensing resistor, converting the current into voltage, and then feeding this voltage back to the chip. The chip adjusts the PWM duty cycle to form a voltage loop negative feedback, thereby maintaining a constant output current. For ease of control, the buck-boost power supply and constant current drive control circuit need to be integrated into the same chip. However, due to the highly integrated design of the chip, its manufacturing cost is relatively high, resulting in a high design cost for the LED driver circuit.

[0031] To address the aforementioned issues, the feedback regulation circuit provided in this application includes a current regulation module, a pull-up module, and a feedback module. The current regulation module is directly connected to the negative terminal of the LED load, enabling rapid and accurate detection of the LED load's operating state and the voltage at its negative terminal. It then dynamically adjusts the second current flowing into the feedback module based on the voltage at the negative terminal of the LED load. The feedback module outputs a feedback current to the input terminal of the power supply chip based on the received second current and the reference voltage. Since the output terminal of the power supply chip is connected to the positive terminal of the LED load, after receiving the feedback current from the feedback module, the power supply chip can adjust the voltage at its output terminal in real time, thus adjusting the voltage at the positive terminal of the LED load and forming a complete negative feedback control loop. Therefore, this application's embodiment constructs a feedback regulation circuit using independent current regulation, pull-up, and feedback modules, eliminating the need for highly integrated buck-boost power supplies and constant current drive control circuits onto a single chip. This significantly reduces the cost of the feedback regulation circuit and lowers the integration requirements of the power supply chip, thereby effectively reducing the manufacturing cost of the power supply chip and the design cost of the LED driver circuit.

[0032] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0033] Figure 1 A schematic block diagram of a feedback regulation circuit 10 according to an embodiment of this application is shown. See also Figure 1 As shown, the feedback regulation circuit 10 includes a current regulation module 101, a pull-up module 102, and a feedback module 103. The current regulation module 101 is electrically connected to the pull-up module 102 and the feedback module 103 respectively. The current regulation module 101 is used to be electrically connected to the negative terminal of the LED load. The feedback module 103 is used to be electrically connected to the input terminal of the power chip. The output terminal of the power chip is electrically connected to the positive terminal of the LED load.

[0034] Specifically, the pull-up module 102 outputs a first current, and the current regulation module 101 is directly connected to the negative terminal of the LED load. It can quickly and accurately detect the operating state of the LED load and the voltage at its negative terminal, and dynamically adjust the second current flowing into the feedback module 103 based on the voltage at the negative terminal of the LED load. The second current is the difference between the first current and the current flowing through the current regulation module 101. The feedback module 103 outputs a feedback current to the input terminal of the power chip based on the received second current and the reference voltage Vref. Since the output terminal of the power chip is connected to the positive terminal of the LED load, after receiving the feedback current output by the feedback module 103, the power chip can adjust the voltage VOUT at its output terminal in real time based on the feedback current, thus adjusting the voltage at the positive terminal of the LED load in real time, thereby forming a complete negative feedback control loop. Therefore, it can be seen that the feedback regulation circuit 10 is constructed by an independent current regulation module 101, pull-up module 102 and feedback module 103 in this embodiment of the application. It is not necessary to use the method of highly integrating the buck-boost power supply and constant current drive control circuit on the same chip to achieve control. This not only significantly reduces the cost of the feedback regulation circuit 10, but also reduces the requirements for the integration of the power chip, thereby effectively reducing the manufacturing cost of the power chip and the design cost of the LED driver circuit.

[0035] It should be noted that since the second current is the difference between the first current and the current flowing through the current regulation module 101, the first current is equal to the second current plus the current flowing through the current regulation module 101. When the current flowing through the current regulation module 101 is zero, the second current is essentially equal to the first current, meaning the first current is directly transmitted to the feedback module 103. At this time, the feedback module 103 outputs a first feedback current to the power chip, and the power chip outputs a first voltage at its output terminal based on the first feedback current. The first voltage can be the minimum voltage set by the designer according to the actual needs of the circuit. When the current flowing through the current regulation module 101 is greater than zero, the current regulation module 101 shunts the first current, causing the second current transmitted to the feedback module 103 to decrease. At this time, the feedback module 103 outputs a second feedback current to the power chip, and the power chip outputs a second voltage at its output terminal based on the second feedback current. The second feedback current is less than the first feedback current, and the second voltage is greater than the first voltage. Therefore, when the current regulation module 101 shunts the first current, it can reduce the feedback current transmitted to the input terminal of the power chip, thereby increasing the voltage VOUT at the output terminal of the power chip, and finally raising the voltage at the negative detection point of the LED load, thus forming a stable voltage negative feedback loop.

[0036] It should be noted that the LED load can be LED beads, LED strips, LED displays, or other LED products.

[0037] In one embodiment of this application, such as Figure 2 As shown, the current regulation module 101 includes a first diode D1. The anode of the first diode D1 is electrically connected to the pull-up module 102 and the feedback module 103, respectively, and the cathode of the first diode D1 is electrically connected to the negative terminal of the LED load.

[0038] Specifically, the first diode D1 has unidirectional conduction characteristics, allowing current to flow only from the anode to the cathode. The first diode D1 only conducts forward when the voltage difference across its terminals reaches its threshold voltage. Specifically, when the LED load is not lit, the voltage at the negative terminal of the LED load is high. At this time, the first diode D1 is reverse-biased, and no current flows through it. The first diode D1 does not shunt the first current, which is directly transmitted to the feedback module 103, causing the feedback module 103 to output the first feedback current. When the LED load starts to light up, the voltage at the negative terminal of the LED load begins to decrease. When the voltage at the negative terminal of the LED load approaches the voltage at the negative terminal detection point, the first diode D1 changes from reverse-biased to forward-biased. At this time, current flows through the first diode D1, which shunts the first current, thereby reducing the second current transmitted to the feedback module 103 and the feedback current transmitted to the power chip, thus increasing the output voltage VOUT of the power chip.

[0039] In one embodiment of this application, such as Figure 2 As shown, the pull-up module 102 includes a first resistor R1. The first end of the first resistor R1 is used to be electrically connected to the first power supply, and the second end of the first resistor R1 is electrically connected to the current regulation module 101 and the feedback module 103 respectively.

[0040] Specifically, the first resistor R1 is used to obtain a first current from the first power supply. In the feedback regulation circuit 10 provided in this application, the first power supply provides energy to the circuit, and the first resistor R1 can convert the electrical energy of the first power supply into current to supply the required current to subsequent modules and devices. This first current can also be called the sinking current, used to provide the current required by the circuit.

[0041] For example, the supply voltage of the first power supply can be selected as +5V. The designer can select the resistance value and resistance accuracy of the first resistor R1 according to the actual situation. For example, the resistance value of the first resistor R1 can be 10kΩ and the accuracy of the first resistor R1 can be ±1%.

[0042] In one embodiment of this application, such as Figure 2 As shown, the feedback module 103 includes a feedback unit 1031 and a unidirectional conduction unit 1032. The feedback unit 1031 is electrically connected to the pull-up module 102, the current regulation module 101 and the unidirectional conduction unit 1032 respectively. The unidirectional conduction unit 1032 is used to be electrically connected to the input terminal of the power chip.

[0043] Specifically, the feedback unit 1031 receives a second current and a reference voltage Vref. The second current characterizes the voltage at the negative terminal of the LED load and the operating state of the LED load. The reference voltage Vref is a stable reference voltage pre-set by the designer according to circuit requirements. The feedback unit 1031 can output a third current based on the second current and the reference voltage Vref. When the second current changes, the third current also changes accordingly; that is, the third current decreases as the second current decreases. The unidirectional conduction unit 1032 can output a feedback current based on the third current, so that the power chip adjusts the output voltage VOUT according to the feedback current. Simultaneously, the unidirectional conduction unit 1032 has a unidirectional conduction characteristic, allowing current to flow only from the feedback unit 1031 to the input terminal of the power chip, while preventing reverse current flow. This characteristic prevents the current at the input terminal of the power chip from interfering with the feedback unit 1031, ensuring the accuracy and stability of the voltage negative feedback loop.

[0044] In one embodiment of this application, such as Figure 2 As shown, the feedback unit 1031 includes a first transistor Q1, a second resistor R2, and a third resistor R3. The first end of the second resistor R2 is electrically connected to the current adjustment module 101 and the pull-up module 102, respectively. The second end of the second resistor R2 is electrically connected to the emitter of the first transistor Q1. The collector of the first transistor Q1 is electrically connected to the first end of the third resistor R3. The base of the first transistor Q1 is used to receive the reference voltage Vref. The second end of the third resistor R3 is electrically connected to the unidirectional conduction unit 1032.

[0045] Specifically, the first transistor Q1 serves as the core component of the feedback unit 1031, with its base receiving the reference voltage Vref. The first transistor Q1 can adjust its collector output current based on the reference voltage Vref and the current signal transmitted from its emitter through the second resistor R2. If the current received by the emitter of the first transistor Q1 decreases, the output current of its collector will also decrease accordingly. The second resistor R2 acts as a shunt or current-limiting resistor, shunting the first current and transmitting the shunted current to the emitter of the first transistor Q1. Simultaneously, the second resistor R2 limits the current flowing into the emitter of the first transistor Q1, preventing excessive current from damaging it and providing some current-limiting protection. The third resistor R3 is positioned between the collector of the first transistor Q1 and the unidirectional conduction unit 1032, achieving current matching with the unidirectional conduction unit 1032 and subsequent currents to meet the normal operating requirements of the unidirectional conduction unit 1032.

[0046] For example, designers can select the resistance value and resistance accuracy of the second resistor R2 and the third resistor R3 according to the actual situation. For example, the resistance value of the second resistor R2 can be 100Ω and the resistance accuracy of the second resistor R2 can be ±1%, and the resistance value of the third resistor R3 can be 100Ω and the resistance accuracy of the third resistor R3 can be ±1%.

[0047] In one embodiment of this application, such as Figure 2 As shown, the feedback unit 1031 also includes a fourth resistor R4. The first end of the fourth resistor R4 is electrically connected to the base of the first transistor Q1, and the second end of the fourth resistor R4 is used to receive the reference voltage Vref.

[0048] Specifically, the fourth resistor R4 is connected to the base of the first transistor Q1, serving as both a current-limiting resistor and a debugging resistor. The resistance of the fourth resistor R4 can be 0Ω, allowing for easy insertion and removal during circuit debugging and measurement. This facilitates changing the circuit connection, measuring base-related parameters independently, or connecting to testing instruments for signal detection. Furthermore, the fourth resistor R4 provides a design margin, allowing for adjustments to the base resistance value to optimize the operating state of the first transistor Q1, such as adjusting the base current or changing the conduction level. Simultaneously, the fourth resistor R4 also provides isolation and filtering, preventing external electromagnetic interference from entering the first transistor Q1 through its base and affecting its normal operation. When the fourth resistor R4 has a specific resistance value, it can also provide current-limiting protection, ensuring the normal operation of the first transistor Q1.

[0049] It should be noted that the resistance values ​​and accuracy of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 listed above can be set according to actual conditions and are not limited here. Similarly, the number of resistors used is not limited; multiple resistors can be selected and connected in series or parallel to replace the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4.

[0050] For example, the first transistor Q1 can be a PNP type transistor.

[0051] It should be noted that the embodiments provided in this application only show one circuit structure as the feedback unit 1031, and do not represent that only this one circuit structure can realize the function of the feedback unit 1031. Other circuit structures that can realize this function can also be substituted, and are not limited to this.

[0052] In one embodiment of this application, such as Figure 2As shown, the unidirectional conduction unit 1032 includes a second diode D2. The anode of the second diode D2 is electrically connected to the feedback unit 1031, and the cathode of the second diode D2 is used to be electrically connected to the power supply chip.

[0053] Specifically, the second diode D2 has unidirectional conduction characteristics, allowing current to flow only from the collector of the first transistor Q1 and through the third resistor R3 to the input terminal of the power supply chip, while preventing current from flowing in the reverse direction. This prevents the current at the input terminal of the power supply chip from interfering with the feedback unit 1031, ensuring the accuracy and stability of the voltage negative feedback loop.

[0054] In one embodiment of this application, such as Figure 2 As shown, the feedback adjustment circuit 10 also includes a reference module 104, which is electrically connected to the feedback module 103 and is used to output a reference voltage Vref to the feedback module 103.

[0055] Specifically, the reference module 104 provides a stable reference voltage Vref for the feedback regulation circuit 10. This reference voltage Vref is transmitted to the base of the first transistor Q1, providing a stable bias voltage for the first transistor Q1. This ensures that the collector current and emitter current of the first transistor Q1 remain relatively stable, thereby enabling the feedback module 103 to operate normally and ultimately achieving precise regulation and stable control of the output voltage VOUT of the power supply chip.

[0056] In one embodiment of this application, such as Figure 2 As shown, the reference module 104 includes a fifth resistor R5 and a sixth resistor R6. The first end of the fifth resistor R5 is used to be electrically connected to the first reference power supply. The second end of the fifth resistor R5 is electrically connected to the first end of the sixth resistor R6 and the feedback module 103, respectively. The second end of the sixth resistor R6 is grounded.

[0057] Specifically, the fifth resistor R5 and the sixth resistor R6 together form a voltage divider circuit. The first reference power supply voltage Vref1 provided by the first reference power supply is divided by the fifth resistor R5 and the sixth resistor R6, and the reference voltage Vref is obtained at the common node of the fifth resistor R5 and the sixth resistor R6. By properly selecting the resistance values ​​of the fifth resistor R5 and the sixth resistor R6, the magnitude of the reference voltage Vref can be accurately set to meet the specific requirements of the feedback adjustment circuit 10.

[0058] It should be noted that the relationship between the reference voltage Vref, the first reference power supply voltage Vref1, the fifth resistor R5, and the sixth resistor R6 satisfies the following formula:

[0059]

[0060] It should be noted that, as Figure 2 As shown, the feedback regulation circuit 10 also includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first capacitor C1, and a third diode D3. The first terminals of both the seventh resistor R7 and the tenth resistor R10 are used to receive the voltage VOUT from the power supply chip's output. The second terminal of the seventh resistor R7 is electrically connected to the first terminal of the eighth resistor R8. The first terminal of the ninth resistor R9 is electrically connected to the second terminal of the eighth resistor R8, the second terminal of the first capacitor C1, the cathode of the second diode D2, and the input terminal of the power supply chip. The second terminal of the ninth resistor R9 is grounded. The first terminal of the first capacitor C1 is electrically connected to the second terminal of the tenth resistor R10. The third diode D3 is connected between the first resistor R1 and ground. The seventh resistor R7 and the eighth resistor R8 form the feedback resistor Rfb, the ninth resistor R9 serves as a pull-down resistor, the tenth resistor R10 and the first capacitor C1 form a filter circuit to filter the voltage VOUT at the output of the power chip, and the third diode D3 serves as a Zener diode. When a transient overvoltage occurs in the circuit due to various reasons (such as power fluctuations, load switching, etc.), the third diode D3 will quickly break down and conduct, clamping the excessive voltage near its Zener value and diverting the excess current to ground, thus preventing the excessive voltage from being applied to the subsequent circuit components and preventing the subsequent circuit components from being damaged due to overvoltage.

[0061] It should be noted that, in combination Figure 2 The circuit connection diagram shown can be used to derive the following formula:

[0062]

[0063] By transforming the above formula, we can obtain:

[0064]

[0065] Where Ui is the input voltage, Uo is the output voltage, Vdio is the forward voltage drop of the first diode D1, and Vfb is the voltage at the FB node. As can be seen above, the voltage at the negative detection point of the LED load is equal to the sum of the first reference power supply voltage Vref1 and the Vbe voltage of the first transistor Q1, minus the voltage drop of the first diode D1.

[0066] Furthermore, the above formula also shows that the slope of the output voltage relative to the input voltage (the speed of input / output adjustment) depends on the ratio of Rfb to R9. To reduce the residual voltage generated by the constant voltage source in the LED driver loop, the input voltage range needs to be narrowed and the output voltage range widened, i.e., the slope needs to be increased. To stabilize the voltage at the negative terminal of the LED load within a smaller voltage range, the slope can be increased to a larger value by decreasing the resistance of R9 and increasing the resistance of Rfb, thereby achieving negative feedback to the voltage loop. However, this method has significant drawbacks. If the ripple frequency of the input voltage signal is within the loop frequency compensation range of the power supply voltage, this signal noise will be amplified, leading to voltage loop oscillations and even power supply voltage instability, resulting in large and small wave phenomena. To avoid the above situation, the voltage loop needs to be adjusted according to the introduced noise frequency, reducing the crossover frequency of the power supply chip's voltage loop and weakening the power supply's load dynamic response, etc.

[0067] It should be noted that there is another implementation method for the feedback regulation circuit 10 in this application, which uses an NPN transistor. This method achieves negative feedback by shunt control on Rfb. However, this approach has a significant impact on the feedforward resistor and capacitor, thereby interfering with the voltage feedback loop of the power supply chip. Therefore, based on the above problems, the existing solution was ultimately adopted.

[0068] This application also discloses an LED driver circuit, including an LED load, a power supply chip U1, and the aforementioned feedback regulation circuit 10. The positive terminal of the LED load is electrically connected to the output terminal of the power supply chip U1, the negative terminal of the LED load is electrically connected to the current regulation module 101 in the feedback regulation circuit 10, and the input terminal of the power supply chip U1 is electrically connected to the feedback module 103 in the feedback regulation circuit 10. The LED driver circuit using the aforementioned feedback regulation circuit 10 can precisely control the current and voltage of the LED load, ensuring stable and efficient operation of the LED load. The feedback regulation circuit 10 monitors the operating status of the LED load in real time and feeds back the feedback current to the power supply chip U1. The power supply chip U1 adjusts the voltage VOUT at its output terminal according to the feedback current to adapt to different operating conditions and LED load characteristics.

[0069] Furthermore, the LED driver circuit in this application also addresses the drawbacks of residual voltage and significant losses in the loop when the system constant voltage source circuit directly drives the LED load, which seriously affects heat dissipation. By constructing negative feedback on the power supply voltage system, the circuit can adjust the voltage according to the changes in the LED load current, thereby reducing loop losses.

[0070] It should be noted that, as Figure 3As shown, the LED driver circuit also mainly includes a driver module, a voltage conversion module, and a filter module. The driver module is used to control the conduction of the LED load, thereby achieving dimming and frequency modulation of the LED load. The voltage conversion module has two switching transistors, which periodically turn on and off to adjust the output voltage VOUT of the power chip. The filter module is used to filter VIN and VOUT to ensure stable and reliable voltage. Since the above modules are all existing technologies, the internal components of each module, the connection relationships between the components, and the specific parameters of each component will not be described in detail here.

[0071] Since the processing and functions implemented by the LED driving circuit in this embodiment are basically the same as the embodiments, principles and examples of the aforementioned feedback adjustment 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.

[0072] 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 feedback regulation circuit, characterized in that, It includes a current regulation module, a pull-up module, and a feedback module. The current regulation module is electrically connected to the pull-up module and the feedback module, respectively. The current regulation module is used to be electrically connected to the negative terminal of the LED load. The feedback module is used to be electrically connected to the input terminal of the power chip. The output terminal of the power chip is electrically connected to the positive terminal of the LED load. The pull-up module is used to output a first current, and the current regulation module is used to regulate the second current flowing into the feedback module according to the voltage of the negative terminal of the LED load. The second current is the difference between the first current and the current flowing through the current regulation module. The feedback module is used to output a feedback current to the input terminal of the power chip according to the second current and the reference voltage. The feedback current is used to instruct the power chip to adjust the voltage at the output terminal of the power chip.

2. The feedback adjustment circuit according to claim 1, characterized in that, The current regulation module includes a first diode, the anode of which is electrically connected to the pull-up module and the feedback module, and the cathode of which is electrically connected to the negative terminal of the LED load.

3. The feedback adjustment circuit according to claim 1, characterized in that, The pull-up module includes a first resistor, a first end of which is electrically connected to a first power supply, and a second end of which is electrically connected to the current regulation module and the feedback module, respectively.

4. The feedback adjustment circuit according to claim 1, characterized in that, The feedback module includes a feedback unit and a unidirectional conduction unit. The feedback unit is electrically connected to the pull-up module, the current regulation module, and the unidirectional conduction unit, respectively. The unidirectional conduction unit is used to be electrically connected to the input terminal of the power chip. The feedback unit is used to receive the second current and the reference voltage, and output a third current to the unidirectional conduction unit according to the second current and the reference voltage. The unidirectional conduction unit is used to output the feedback current to the power chip according to the third current.

5. The feedback adjustment circuit according to claim 4, characterized in that, The feedback unit includes a first transistor, a second resistor, and a third resistor. The first end of the second resistor is electrically connected to the current regulation module and the pull-up module, respectively. The second end of the second resistor is electrically connected to the emitter of the first transistor. The collector of the first transistor is electrically connected to the first end of the third resistor. The base of the first transistor is used to receive the reference voltage. The second end of the third resistor is electrically connected to the unidirectional conduction unit.

6. The feedback adjustment circuit according to claim 5, characterized in that, The feedback unit further includes a fourth resistor, the first end of which is electrically connected to the base of the first transistor, and the second end of which is used to receive the reference voltage.

7. The feedback adjustment circuit according to claim 4, characterized in that, The unidirectional conduction unit includes a second diode, the anode of which is electrically connected to the feedback unit, and the cathode of which is electrically connected to the power chip.

8. The feedback regulation circuit according to any one of claims 1-7, characterized in that, The feedback adjustment circuit further includes a reference module, which is electrically connected to the feedback module and is used to output the reference voltage to the feedback module.

9. The feedback adjustment circuit according to claim 8, characterized in that, The reference module includes a fifth resistor and a sixth resistor. The first end of the fifth resistor is used to be electrically connected to the first reference power supply. The second end of the fifth resistor is electrically connected to the first end of the sixth resistor and the feedback module, respectively. The second end of the sixth resistor is grounded.

10. An LED driving circuit, characterized in that, The device includes an LED load, a power supply chip, and a feedback regulation circuit as described in any one of claims 1-9. The positive terminal of the LED load is electrically connected to the output terminal of the power supply chip, the negative terminal of the LED load is electrically connected to the current regulation module in the feedback regulation circuit, and the input terminal of the power supply chip is electrically connected to the feedback module in the feedback regulation circuit.

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