Linear constant current control circuit

Abstract

The utility model belongs to the technical field of constant current control, and relates to a linear constant current control circuit, which comprises an input protection circuit, a rectifying circuit, a filtering protection circuit, a compensation feedback and power supply circuit, an integrated control circuit, a voltage difference compensation circuit, a current sampling circuit and an output circuit which are electrically connected in sequence, the input protection circuit is used for preprocessing an alternating current input power supply to protect a subsequent circuit from being impacted by abnormal voltage and current, the rectification circuit is used for converting an alternating current power supply into a direct current power supply, and the filtering protection circuit is used for filtering pulsation components in rectified direct current voltage to enable output voltage to be smoother. The compensation feedback and power supply circuit is used for maintaining the output current constant, and the integrated control circuit is used for receiving a current signal from the compensation feedback and power supply circuit and adjusting the output current. The peripheral circuit is simple, the driving size is small, the space cost is reduced, the surge capacity of the system is improved, the stroboflash-free requirement of the lamp is met, and the new national standard harmonic certification requirement is met.

Description

Technical Field

[0001] The utility model relates to the technical field of constant current control, and more specifically, to a linear constant current control circuit. Background Art

[0002] A linear constant current control circuit is an important circuit composition method in electronics. Its core lies in achieving precise regulation of current by controlling impedance, thereby maintaining a constant current output state.

[0003] The main advantages of the linear constant current control circuit are its high output accuracy, small ripple, and short current edge. These characteristics enable it to have a wide range of applications in multiple fields. In the field of LED lighting, since LEDs are extremely sensitive to current, excessive current will cause overheating and shortened lifespan, while insufficient current will affect their lighting effect. Therefore, the linear constant current control circuit becomes an ideal choice for driving LEDs, which can ensure that each LED obtains a stable current, thereby guaranteeing the consistency of light brightness and extending the service life of LEDs. The linear constant current control circuit is also widely used in fields such as precision instruments and high-precision sensors. In these applications, extremely high requirements are placed on the stability and accuracy of current. The linear constant current control circuit can provide a stable current output, ensuring the accuracy of measurement and control. At the same time, during the battery charging process, the linear constant current source can also provide a stable charging current to prevent overcharging or undercharging, thereby extending the service life of the battery. In the field of medical equipment, the linear constant current control circuit also plays an important role. Constant current is often required in medical equipment to ensure the treatment effect, such as in equipment like electrotherapy devices and cardiac pacemakers. The linear constant current source is widely used due to its stability and reliability.

[0004] In the prior art, for the design of the linear constant current control circuit to achieve non-flickering, a capacitor is connected in parallel after the rectifier bridge for filtering to obtain a positive DC output voltage. However, due to the charge and discharge characteristics of the capacitor, after the capacitor is applied with voltage, since the voltage across the capacitor cannot change suddenly, it gradually builds up voltage during the charging process; while the current reaches its maximum value immediately when the voltage is applied, that is, the voltage across its two ends is the minimum when the initial charging current is the largest. The phase difference between these two is 90 degrees, so there will be a deviation in the voltage and current phases, resulting in a phase shift, and the PF value is only about 0.5, and the harmonics do not meet the requirements of the new national standard. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is that in the prior art, the design of the linear constant current control circuit has harmonics that do not meet the requirements of the new national standard. In view of the above-mentioned defects of the prior art, a linear constant current control circuit is provided, including:

[0006] The input protection circuit, the rectifier circuit, the filter protection circuit, the compensation feedback and power supply circuit, the integrated control circuit, the voltage difference compensation circuit, the current sampling circuit and the output circuit are electrically connected in sequence. The input protection circuit is used to pre-process the AC input power supply to protect the subsequent circuit from the impact of abnormal voltage and current. The rectifier circuit is used to convert the AC power supply into a DC power supply. The filter protection circuit is used to filter out the pulsating components in the rectified DC voltage to make the output voltage smoother. The compensation feedback and power supply circuit is used to maintain the constancy of the output current. The integrated control circuit is used to receive the current signal from the compensation feedback and power supply circuit and adjust the output current. The voltage difference compensation circuit is used to adjust and compensate the control signal by real-time detection of changes in the power supply voltage and output current to ensure that the output current always remains constant. The current sampling circuit is used to collect information on the output current in real time and provide a feedback signal to the integrated control circuit. The output circuit is used to output the controlled stable current to the load.

[0007] Preferably, the input protection circuit comprises: one end of a fuse F1 is connected to one end of a varistor RV1.

[0008] Preferably, the rectifier circuit comprises: a rectifier bridge DB1.

[0009] Preferably, the filtering protection circuit includes: the positive electrode of the diode D1 is connected to one end of the varistor RV2, the other end of the varistor RV2 is respectively connected to one end of the resistor R2, the negative electrode of the capacitor CE1, and the negative electrode of the diode D2, the positive electrode of the diode D2 is grounded, and the negative electrode of the diode D1 is respectively connected to the other end of the resistor R2 and the positive electrode of the capacitor CE1.

[0010] Preferably, the integrated control circuit comprises: a linear constant current LED control chip U1.

[0011] Preferably, the output circuit comprises: a cathode of a photosensitive diode VD1 is connected to an anode of a photosensitive diode VD2.

[0012] Preferably, the compensation feedback and power supply circuit includes: one end of the capacitor C1 is connected to the pin 5 of the linear constant current LED control chip U1, and the pin 3 of the linear constant current LED control chip U1 is connected to one end of the resistor R1.

[0013] Preferably, the current sampling circuit comprises: one end of the resistor RS1 is connected to the pin 6 of the linear constant current LED control chip U1 , and the pin 8 of the linear constant current LED control chip U1 is connected to one end of the resistor RS2 .

[0014] Preferably, the voltage difference compensation circuit comprises: a pin 1 of the linear constant current LED control chip U1 is connected to one end of a resistor Rvd1 and one end of a resistor Rvd2 respectively.

[0015] Preferably, the linear constant-current LED control chip U1 is BP5228FE.

[0016] Implementing the linear constant-current control circuit of the present utility model has the following beneficial effects: By adopting an input protection circuit, a rectification circuit, a filtering protection circuit, a compensation feedback and power supply circuit, an integrated control circuit, a voltage difference compensation circuit, a current sampling circuit, and an output circuit that are electrically connected in sequence, the input protection circuit is used to preprocess the AC input power supply to protect the subsequent circuits from the impact of abnormal voltages and currents. The rectification circuit is used to convert the AC power supply into a DC power supply. The filtering protection circuit is used to filter out the pulsating components in the rectified DC voltage to make the output voltage smoother. The compensation feedback and power supply circuit is used to maintain the constancy of the output current. The integrated control circuit is used to receive the current signal from the compensation feedback and power supply circuit and adjust the output current. The voltage difference compensation circuit is used to adjust and compensate the control signal by detecting the changes in the power supply voltage and the output current in real time to ensure that the output current always remains constant. The current sampling circuit is used to collect the information of the output current in real time and provide a feedback signal to the integrated control circuit. The output circuit is used to output the controlled stable current to the load; while meeting the new national standard, it also meets the requirement of no stroboscopic. By using an external resistor to adjust the charging current of the electrolytic capacitor, the valley voltage of the electrolytic capacitor is 3 - 5V higher than the actual lamp bead voltage. Meeting the requirement of no stroboscopic for the lamp; having strong surge ability, a linear new national standard solution, because the electrolytic capacitor needs to be charged, the starting transient current may be relatively large. By connecting a varistor from the negative electrode of the electrolytic capacitor to the GND ground, the surge ability of the system can be improved; the peripheral circuit is simple, the driving volume is small, and the space cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings. The present utility model will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0018] Figure 1 is a schematic diagram of the composition of the linear constant-current control circuit of the present utility model;

[0019] Figure 2 is a circuit diagram of a preferred embodiment of the linear constant-current control circuit of the present utility model;

[0020] Figure 3 is Figure 2 a circuit diagram with module frames removed.

[0021] In the figure, 10 is an input protection circuit, 20 is a rectification circuit, 30 is a filtering protection circuit, 40 is a compensation feedback and power supply circuit, 50 is a current sampling circuit, 60 is a voltage difference compensation circuit, and 70 is an output circuit. Specific embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0024] In addition, if there are descriptions such as "first" and "second" in the embodiments of the present invention, the descriptions of "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0025] Figure 1 is a schematic diagram of the composition of the linear constant current control circuit of the present invention; Figure 2 is a circuit diagram of a preferred embodiment of the linear constant current control circuit of the present invention; Figure 3 is Figure 2 the circuit diagram with the module frames removed. Please refer to Figures 1 to 3, in the linear constant current control circuit provided by the first embodiment of the present utility model, it at least includes an input protection circuit 10, a rectification circuit 20, a filtering protection circuit 30, a compensation feedback and power supply circuit 40, an integrated control circuit, a voltage difference compensation circuit 60, a current sampling circuit 50, and an output circuit 70 that are electrically connected in sequence. The input protection circuit 10 is used to preprocess the AC input power supply to protect the subsequent circuits from the impact of abnormal voltages and currents. The rectification circuit 20 is used to convert the AC power supply into a DC power supply. The filtering protection circuit 30 is used to filter out the pulsating components in the rectified DC voltage to make the output voltage smoother. The compensation feedback and power supply circuit 40 is used to maintain the constancy of the output current. The integrated control circuit is used to receive the current signal from the compensation feedback and power supply circuit 40 and adjust the output current. The voltage difference compensation circuit 60 is used to adjust and compensate the control signal by detecting the changes in the power supply voltage and the output current in real time to ensure that the output current always remains constant. The current sampling circuit 50 is used to collect the information of the output current in real time and provide a feedback signal for the integrated control circuit. The output circuit 70 is used to output the controlled stable current to the load.

[0026] The input protection circuit 10 is mainly used to protect the entire circuit from the impact of external abnormal voltages and currents, such as overcurrent, overvoltage, reverse polarity, etc. In specific implementation, the input protection circuit 10 includes: one end of the fuse F1 is connected to one end of the varistor RV1. The fuse F1 provides short-circuit protection, and the varistor RV1 prevents reverse voltage from being connected to ensure the safety of the circuit.

[0027] The rectifier bridge circuit is responsible for converting the input alternating current (AC) into direct current (DC) to provide a stable DC power supply for the subsequent circuits. In specific implementation, the rectification circuit 20 includes: a rectifier bridge DB1. The rectifier bridge DB1 realizes full-wave rectification of the alternating current through a bridge circuit composed of four diodes to improve the power conversion efficiency.

[0028] During specific implementation, the filtering and protection circuit 30 includes: the positive electrode of diode D1 is connected to one end of varistor RV2, and the other end of varistor RV2 is respectively connected to one end of resistor R2, the negative electrode of capacitor CE1, and the negative electrode of diode D2. The positive electrode of diode D2 is grounded, and the negative electrode of diode D1 is respectively connected to the other end of resistor R2 and the positive electrode of capacitor CE1. The filtering and protection circuit 30 includes a filtering circuit and an additional protection mechanism, which are used to filter out the ripple and noise in the rectified direct current, and at the same time provide further overvoltage and overcurrent protection. The filtering and protection circuit 30 can effectively suppress high-frequency harmonics and make the output voltage smoother and more stable. The protection mechanism is realized by varistor RV2 and is used to cut off the power supply or limit the current in case of abnormal conditions. Through the energy storage and filtering effect of capacitor CE1, the ripple coefficient of the output voltage is effectively reduced and the power supply quality is improved. In addition, the filtering and protection circuit 30 can also suppress the electromagnetic interference inside the power supply and protect other electronic devices from interference.

[0029] The integrated control circuit is the core of the entire linear constant current control circuit and is responsible for implementing the linear two-stage constant current control strategy. It integrates multiple functional modules, such as a reference voltage generation module, a current control module, etc., and realizes the constant current drive of loads such as LED lamp strings by precisely controlling the current output. The integrated control circuit uses advanced control algorithms and high-speed operation capabilities to ensure that the entire linear constant current control circuit can still work stably under complex working conditions. During specific implementation, the integrated control circuit includes a linear constant current LED control chip U1. The linear constant current LED control chip U1 includes but is not limited to BP5228FE, etc. BP5228FE is a linear constant current LED control chip with high PF and no stroboscopic effect, which is mainly used for driving various light sources and lamps with high power factor under high-voltage input, can meet the new national standard in China, and at the same time has good non-stroboscopic characteristics. BP5228FE supports multi-segment conduction operation and is compatible with the lighting requirements under low input voltage, that is, it can still light up at a low voltage of 120Vac, so as to meet the acceptance requirements of some lighting equipment applied to real estate projects.

[0030] The output circuit 70 includes: the negative electrode of photosensitive diode VD1 is connected to the positive electrode of photosensitive diode VD2. The output circuit 70 is responsible for outputting the stable current or voltage generated by the control circuit to the load, such as an LED lamp string, etc. In the output circuit 70, filtering elements can also be included to further smooth the output voltage or current waveform and reduce harmonic interference. At the same time, the output circuit 70 also needs to have sufficient driving ability and protection mechanism to ensure the normal operation and safety of the load.

[0031] The output circuit 70 is the last link of the linear constant current control circuit and is responsible for outputting the controlled stable current to the load. The output circuit 70 is used to smooth the output current waveform, reduce electromagnetic interference, and protect the load from the impact of abnormal current. It should be noted that the design of the output circuit 70 needs to consider factors such as load characteristics, working environment, and safety requirements to ensure the stability and reliability of the circuit.

[0032] The compensation feedback and power supply circuit 40 provides a stable operating voltage for the entire linear constant current control circuit to ensure the normal operation of each functional module. The compensation feedback and power supply circuit 40 also feeds back part of the output signal to the input terminal or the control terminal by monitoring the output voltage or current to adjust the operating state of the entire linear constant current control circuit and achieve closed-loop control. This helps to improve the stability and accuracy of the entire linear constant current control circuit and reduce output fluctuations. In specific implementation, the compensation feedback and power supply circuit 40 includes: one end of the capacitor C1 is connected to the pin 5 of the linear constant current LED control chip U1, and the pin 3 of the linear constant current LED control chip U1 is connected to one end of the resistor R1. The compensation feedback and power supply circuit 40 is a key part of the linear constant current control circuit and is responsible for maintaining the constancy of the output current. The compensation feedback and power supply circuit 40 detects the output current in real time through the sampling resistor R1, converts the current signal into a voltage signal, and compares it with the reference voltage. According to the comparison result, precise control of the output current is achieved. At the same time, this circuit is also responsible for providing a stable power supply voltage for the entire linear constant current control circuit to ensure the normal operation of each functional module.

[0033] In specific implementation, the current sampling circuit 50 includes: one end of the resistor RS1 is connected to the pin 6 of the linear constant current LED control chip U1, and the pin 8 of the linear constant current LED control chip U1 is connected to one end of the resistor RS2. The current sampling circuit 50 is used to monitor the current value in the circuit in real time and convert the current signal into a voltage signal for use by the control circuit. The current sampling circuit 50 can accurately reflect the current change in the circuit and provide an important basis for current control and protection. The current sampling circuit 50 converts the current signal into a voltage signal and performs quantitative adjustment through a proportional amplifier, and inputs it to processing units such as the linear constant current LED control chip U1. The accuracy of the current sampling circuit 50 directly affects the accuracy and stability of the linear constant current control circuit.

[0034] The voltage difference compensation circuit 60 is used to compensate for voltage drops or voltage fluctuations in the circuit, ensuring the stability and accuracy of the output voltage. For example, it is used to compensate for the change in the forward voltage drop of the LED with current and temperature to maintain a constant current output, etc. In specific implementation, the voltage difference compensation circuit 60 includes: Pin 1 of the linear constant current LED control chip U1 is respectively connected to one end of the resistor Rvd1 and one end of the resistor Rvd2. The voltage difference (abbreviated as VD) compensation circuit refers to a circuit that achieves specific control objectives by adjusting the voltage difference in the circuit. VD represents the voltage difference between two points in the circuit, and this parameter plays a crucial role in circuit design and debugging. The VD compensation circuit monitors and adjusts this voltage difference to achieve precise control of the circuit working state and performance. The VD compensation circuit is mainly used to regulate the current waveform to reduce or eliminate harmonic components, thereby improving the power quality and system stability. The voltage difference compensation circuit 60 is used to improve the accuracy and stability of the linear constant current control circuit. In practical applications, due to factors such as power supply voltage fluctuations and component aging, the output current may be affected to a certain extent. The voltage difference compensation circuit 60 adjusts the control signal by detecting the changes in the power supply voltage and output current in real time to compensate for these effects and ensure that the output current always remains constant.

[0035] The voltage difference compensation circuit 60 has the following functions:

[0036] First, harmonic suppression: In the power system, nonlinear loads such as power electronic devices and rectifiers will generate a large amount of harmonic currents. These harmonic currents will not only increase the system losses but also have an adverse impact on the power grid and equipment, such as reducing the power factor, increasing the temperature rise, and causing equipment failures. The VD compensation circuit monitors the harmonic components in the current in real time and generates corresponding compensation voltages or currents to cancel or weaken the harmonic currents, thereby effectively suppressing the generation and propagation of harmonics.

[0037] Second, improving the power factor: The existence of harmonic currents will cause the system power factor to decrease, affecting the effective utilization of electric energy. The VD compensation circuit adjusts the phase relationship between the voltage and current in the circuit to make them as synchronous as possible, thereby improving the power factor. This not only helps to reduce the transmission of reactive current but also reduces the copper loss and iron loss of the system, improving the transmission efficiency of the power grid.

[0038] Third, protecting the power grid and equipment: Harmonic currents have a potential destructive effect on the power grid and equipment. Through the precise control of the VD compensation circuit, the magnitude and frequency range of harmonic currents can be effectively reduced, thereby reducing the impact and damage on the power grid and equipment. This is of great significance for ensuring the stable operation of the power grid and extending the service life of equipment.

[0039] Fourth, optimize the circuit performance: In the linear two-stage constant current control circuit, the VD compensation circuit can also adjust the working state of the circuit according to actual needs. For example, when the load changes, by adjusting the parameters of the VD compensation circuit, the constancy and stability of the circuit output current can be maintained, thereby ensuring the efficient operation of the system under different working conditions.

[0040] Driven by the new national standard, the power system has put forward higher requirements for harmonic control. The linear two-stage constant current control circuit combined with the VD compensation circuit provides an efficient and reliable solution for harmonic suppression. By precisely controlling the VD parameters in the circuit, this solution can effectively reduce the generation and propagation of harmonic currents, improve the power factor and power quality of the system. At the same time, this solution also has good adaptability and stability, and can meet the harmonic control requirements under different working conditions.

[0041] The working principle of the linear constant current control circuit of the present utility model is as follows: The 220V AC input passes through the input fuse (F1) and varistor RV1, and then passes through the rectifier bridge DB1 (AC-DC), the filter circuit (electrolytic capacitor EC1, chip resistor R2). The D1 / D2 terminal supplies power to the chip through the internal high-voltage JFET. When the voltage at the D1 / D2 terminal exceeds 10V, the chip starts to work and supplies power to the LED light source normally. By precisely adjusting the charging current rate of the capacitor through external resistors (RS2, Rvd1, Rvd2), the Di / dt of the input current is reduced. The charging current becomes smoother, resulting in a more lagging phase angle of the current, correcting the phase angle, thereby improving harmonics and meeting the harmonic certification requirements of the new national standard. It can solve the problem of low output voltage application in the linear solution, such as about 235V. By adjusting the compensation resistor on the COMP capacitor, the problem of power decline caused by the increase in input voltage can be improved. By setting the CS2 line compensation built-in and adding a chip capacitor between COMP and ground, the LED current can be ensured to be non-flickering. By adding a varistor in front of the rectifier bridge, paralleling a fast recovery diode between the chip ground and diode D1, and adding a resistor Rvd2 between the diode D1 pin and the VD pin at the same time, the surge capacity of the system can be improved to meet the application with high surge requirements. By adding a VD compensation pin and compensating through resistor Rvd1 and resistor Rvd2, when the input voltage increases, the charging current of the electrolytic capacitor can be reduced through compensation, achieving better linear regulation rate and efficiency. At the same time, the instantaneous high power of diode D1 during startup can be reduced, avoiding circuit damage and improving circuit stability.

[0042] Through the design of the above embodiments of the present utility model, the beneficial effects are as follows:

[0043] By adopting an input protection circuit, a rectification circuit, a filtering protection circuit, a compensation feedback and power supply circuit, an integrated control circuit, a voltage difference compensation circuit, a current sampling circuit and an output circuit which are electrically connected in sequence, the input protection circuit is used for preprocessing the AC input power supply to protect the subsequent circuits from the impact of abnormal voltage and current. The rectification circuit is used for converting the AC power supply into a DC power supply. The filtering protection circuit is used for filtering out the pulsating components in the rectified DC voltage to make the output voltage smoother. The compensation feedback and power supply circuit is used for maintaining the constancy of the output current. The integrated control circuit is used for receiving the current signal from the compensation feedback and power supply circuit and adjusting the output current. The voltage difference compensation circuit is used for adjusting and compensating the control signal by detecting the changes of the power supply voltage and the output current in real time to ensure that the output current always remains constant. The current sampling circuit is used for collecting the information of the output current in real time and providing a feedback signal for the integrated control circuit. The output circuit is used for outputting the controlled stable current to the load; By adopting a capacitor in series with an IC, the control current mainly consists of two parts (one part is the reference current: the CS1 pin obtains the voltage from the RS2 resistor and operates with the internal reference voltage to achieve the constant current charging and discharging of the electrolytic capacitor and complete the shunt control; one part is the compensation coefficient: the VD pin obtains the voltage division circuit composed of the resistors Rvd1 and Rvd2 for sampling compensation to realize the internal current control). These two parts are used to adjust the charging current of the electrolytic capacitor, reduce the Di / dt of the input current of the electrolytic capacitor, shift the phase of the electrolytic current and voltage, correct the phase angle of the current and voltage, make the input current waveform reach the current threshold before 60° and reach the peak before 65°, and at the same time slow down the discharging rate of the electrolytic capacitor so that it cannot drop below the current threshold before 90°. Thereby improving the PF value and harmonics to meet the requirements of the new national standard harmonic certification; While meeting the new national standard, it also meets the requirement of no stroboscopic. The charging current of the electrolytic capacitor is adjusted by using an external resistor, so that the valley voltage of the electrolytic capacitor is 3 - 5V higher than the actual lamp bead voltage. Meeting the requirement of no stroboscopic for the lamp; Strong surge capacity, linear new national standard scheme. Because the electrolytic capacitor needs to be charged, the starting transient current may be relatively large. By connecting a varistor from the negative electrode of the electrolytic capacitor to the GND ground, the surge capacity of the system can be improved; The peripheral circuit is simple, the driving volume is small, and the space cost is reduced.

[0044] The present utility model is described according to specific embodiments, but those skilled in the art should understand that various changes and equivalent substitutions can be made without departing from the scope of the present utility model. In addition, in order to adapt to the specific situation of the technology of the present utility model, many modifications can be made to the present utility model without departing from its protection scope. Therefore, the present utility model is not limited to the specific embodiments disclosed herein, but includes all embodiments falling within the protection scope of the claims.

Claims

1. A linear constant current control circuit, characterized in that: include: The input protection circuit, the rectifier circuit, the filter protection circuit, the compensation feedback and power supply circuit, the integrated control circuit, the voltage difference compensation circuit, the current sampling circuit and the output circuit are electrically connected in sequence. The input protection circuit is used to pre-process the AC input power supply to protect the subsequent circuit from the impact of abnormal voltage and current. The rectifier circuit is used to convert the AC power supply into a DC power supply. The filter protection circuit is used to filter out the pulsating components in the rectified DC voltage to make the output voltage smoother. The compensation feedback and power supply circuit is used to maintain the constancy of the output current. The integrated control circuit is used to receive the current signal from the compensation feedback and power supply circuit and adjust the output current. The voltage difference compensation circuit is used to adjust and compensate the control signal by real-time detection of changes in the power supply voltage and output current to ensure that the output current always remains constant. The current sampling circuit is used to collect information on the output current in real time and provide a feedback signal to the integrated control circuit. The output circuit is used to output the controlled stable current to the load.

2. The linear constant current control circuit according to claim 1, characterized in that: The input protection circuit includes: one end of a fuse F1 is connected to one end of a varistor RV1.

3. The linear constant current control circuit according to claim 1, characterized in that: The rectifier circuit includes: a rectifier bridge DB1.

4. The linear constant current control circuit according to claim 1, characterized in that: The filtering protection circuit includes: the positive electrode of the diode D1 is connected to one end of the varistor RV2, the other end of the varistor RV2 is respectively connected to one end of the resistor R2, the negative electrode of the capacitor CE1, and the negative electrode of the diode D2, the positive electrode of the diode D2 is grounded, and the negative electrode of the diode D1 is respectively connected to the other end of the resistor R2 and the positive electrode of the capacitor CE1.

5. The linear constant current control circuit according to claim 1, characterized in that: The integrated control circuit includes: a linear constant current LED control chip U1.

6. The linear constant current control circuit according to claim 1, characterized in that: The output circuit includes: a cathode of a photosensitive diode VD1 is connected to an anode of a photosensitive diode VD2.

7. The linear constant current control circuit according to claim 5, characterized in that: The compensation feedback and power supply circuit includes: one end of the capacitor C1 is connected to the pin 5 of the linear constant current LED control chip U1, and the pin 3 of the linear constant current LED control chip U1 is connected to one end of the resistor R1.

8. The linear constant current control circuit according to claim 5, characterized in that: The current sampling circuit includes: one end of the resistor RS1 is connected to the pin 6 of the linear constant current LED control chip U1, and the pin 8 of the linear constant current LED control chip U1 is connected to one end of the resistor RS2.

9. The linear constant current control circuit according to claim 5, characterized in that: The voltage difference compensation circuit includes: a pin 1 of a linear constant current LED control chip U1 is connected to one end of a resistor Rvd1 and one end of a resistor Rvd2 respectively.

10. The linear constant current control circuit according to claim 5, characterized in that: The linear constant current LED control chip U1 is BP5228FE.

Images