Constant current sampling circuit and device

Abstract

The utility model provides a constant current sampling circuit and device, and relates to the technical field of power electronics. The constant current sampling circuit comprises a load unit, a sampling unit, a control unit and an adjusting unit. The adjusting unit is used for receiving a modulation signal and converting the modulation signal into a standard parameter. And the control unit compares the standard parameter with the load parameter of the loop acquired by the sampling unit to determine the on and off of the switching tube, so that the constant current of the constant current sampling circuit under the current standard parameter is realized. And the adjusting unit obtains different modulation signals, so that the gain change of the control unit is controlled under different standard parameters, and further the light modulation is simulated in the constant current circuit, the brightness degree of the LED is adjusted, and the color temperature of the LED load is adjusted in real time. The constant-current power supply can be applied to the cathode end of a constant-current device, realizes the constant current of the power supply by using simple components, and reduces the cost of the device.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, and in particular to a constant current sampling circuit and a device. Background Art

[0002] In the prior art, a current constant current IC chip and a single chip microcomputer are used to implement a constant current dimming circuit, and the brightness of the lamp is adjusted by adjusting the current value of the constant current circuit.

[0003] However, the above method is highly dependent on hardware, and actually completes simple judgment steps on the single-chip microcomputer, which causes a great waste of single-chip microcomputer performance. In addition, the multi-channel constant current circuit has low efficiency and complex structure. In particular, when the load unit is a load unit, the complex structure of the multi-channel constant current circuit will cause the constant current sampling circuit to adjust the brightness of the LED load, and the dimming change is not soft enough. Utility Model Content

[0004] The purpose of the utility model is to provide a constant current sampling circuit and device, which can be applied to the cathode end of the constant current device, and use simple components, such as inductors, resistors and switch tubes, to achieve constant current of the power supply. And the PWM signal can be converted into an analog signal to directly adjust the gain of the operational amplifier. Thereby, analog dimming can be achieved on the constant current circuit, and the color temperature of the LED load can be adjusted in real time. And the response speed is fast, the cost is low, and the LED load changes more gently.

[0005] The utility model provides a technical solution:

[0006] In a first aspect, the utility model provides a constant current sampling circuit, comprising: a load unit, a sampling unit and a control unit; the control unit comprises a switch tube and a main control module; the main control module is connected to the switch tube and the sampling unit respectively;

[0007] The load unit is used to connect to the first power supply; the load unit forms a loop with the switch tube and the sampling unit in sequence; wherein the load unit includes an inductive element and an LED device;

[0008] The sampling unit is used to obtain the load parameters in the loop;

[0009] The main control module is used to determine a control signal according to the load parameter to control the switch tube to be turned on or off;

[0010] When the main control module outputs the first control signal, the switch tube is turned on;

[0011] When the main control module outputs the second control signal, the switch tube is turned off;

[0012] The sampling unit is arranged at the grounding end of the load unit.

[0013] Furthermore, the constant current sampling circuit further includes at least one regulating unit, and the regulating unit is connected to the main control module;

[0014] The adjustment unit is used to receive the modulation signal and convert the modulation signal into a standard parameter;

[0015] When the load parameter is greater than the standard parameter, the main control module outputs a first control signal;

[0016] When the load parameter is less than the standard parameter, the main control module outputs a second control signal.

[0017] Further, the main control module includes at least one first operational amplifier unit; the output end of the sampling unit is connected to the first input end of the first operational amplifier unit; the output end of the regulating unit is connected to the second input end of the first operational amplifier unit; the output end of the first operational amplifier unit is connected to the control end of the switch tube;

[0018] Wherein, the first operational amplifier unit is used to determine a control signal according to a value between the standard parameter and the load parameter to control the switch tube to be turned on or off;

[0019] When the load parameter is greater than the standard parameter, the main control module outputs a first control signal;

[0020] When the load parameter is less than the standard parameter, the main control module outputs a second control signal.

[0021] Furthermore, the main control module also includes a second operational amplifier unit; the input end of the first operational amplifier unit is connected to the output end of the sampling unit; the input end of the second operational amplifier unit is connected to the first input end of the first operational amplifier unit; wherein the second operational amplifier unit is used to amplify the load parameter.

[0022] Further, the adjustment unit includes a first resistor, a second resistor, a third resistor and a first capacitor; one end of the first resistor serves as an input end of the adjustment unit; the other end of the first resistor is respectively connected to one end of the second resistor, one end of the third resistor and one end of the first capacitor; the other end of the second resistor is connected to the other end of the first capacitor and is grounded; the other end of the third resistor is connected to the control unit.

[0023] Furthermore, the first operational amplifier unit includes a first operational amplifier and a first input resistor; the first input end of the first operational amplifier is connected to the output end of the sampling unit through the first input resistor; the second input end of the first operational amplifier is connected to the output end of the adjustment unit; the output end of the first operational amplifier is connected to the control end of the switch tube.

[0024] Furthermore, the second operational amplifier unit includes a first feedback resistor, a second operational amplifier, a second input resistor and a third input resistor; the first input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the first feedback resistor; the first input terminal of the second operational amplifier is also connected to one terminal of the sampling unit through the second input resistor; the second input terminal of the second operational amplifier is connected to the other terminal of the sampling unit through the third input resistor.

[0025] Furthermore, the switch tube includes a switch tube and a regulating submodule; the switch tube is connected in series in the loop, and the control end of the switch tube is respectively connected to the output end of the first operational amplifier unit and the regulating submodule; the regulating submodule is used to connect to the first power supply to adjust the shutdown time of the switch tube.

[0026] Furthermore, the regulating submodule includes a first voltage stabilizing diode and a fourth resistor; the anode of the first voltage stabilizing diode is connected to the regulating unit; the cathode of the first voltage stabilizing diode is connected to one end of the fourth resistor; the other end of the fourth resistor is respectively connected to the output end of the first operational amplifier unit and the control end of the switching tube.

[0027] In a second aspect, the utility model further provides a constant current sampling device, comprising the constant current sampling circuit described in any one of the above-mentioned first aspect.

[0028] The beneficial effects of a constant current sampling circuit and device provided by the utility model are:

[0029] Among them, the constant current sampling circuit includes: a load unit, a sampling unit, a control unit and an adjustment unit; the control unit includes a switch tube and a main control module; the main control module is connected to the switch tube, the sampling unit and the adjustment unit respectively; the load unit is used to connect to the first power supply; the load unit forms a loop with the switch tube and the sampling unit in turn; wherein the adjustment unit receives a modulation signal and converts the modulation signal into a standard parameter. The control unit compares the standard parameter with the load parameter of the loop obtained by the sampling unit to determine the conduction and closing of the switch tube, thereby realizing the constant current of the constant current sampling circuit under the current standard parameter. The adjustment unit obtains different modulation signals, thereby controlling the gain change of the control unit under different standard parameters, and then simulating dimming in the constant current circuit, adjusting the brightness of the LED, and adjusting the color temperature of the LED load in real time. The utility model can be applied to the cathode end of the constant current device, and uses simple components to realize the constant current of the power supply, thereby reducing the cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is one of the structural schematic diagrams of the constant current sampling circuit provided in the embodiment of the utility model.

[0032] Figure 2 The second structural schematic diagram of the constant current sampling circuit provided in the embodiment of the utility model.

[0033] Figure 3 It is a structural schematic diagram of the main control module in the embodiment of the utility model.

[0034] Figure 4 The third structural schematic diagram of the constant current sampling circuit provided in the embodiment of the utility model.

[0035] Figure 5 This is one of the structural schematic diagrams of the control unit in the embodiment of the utility model.

[0036] Figure 6 This is one of the circuit diagrams of the control unit in the embodiment of the utility model.

[0037] Figure 7 This is the second circuit diagram of the control unit in the embodiment of the utility model.

[0038] Figure 8 This is one of the circuit diagrams of the regulating unit in the embodiment of the utility model.

[0039] Fig. 9 Schematic diagram of the circuit of the regulating submodule in the embodiment of the utility model.

[0040] Fig.10 Schematic diagram of the circuit of the switch tube in the embodiment of the utility model.

[0041] Fig.11 A circuit diagram of a constant current sampling circuit provided in an embodiment of the utility model.

[0042] Icon: 100-constant current sampling circuit; 101-load unit; 102-sampling unit; 103-control unit; 104-regulation unit; 301-switch tube; 302-main control module. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of the present utility model, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present utility model.

[0047] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] As described in the prior art, in the prior art, a current constant current IC chip and a single chip microcomputer are usually used to complete a constant current dimming circuit, and then the brightness of the lamp is adjusted by adjusting the current value of the constant current circuit.

[0050] The above method is highly dependent on hardware, and actually completes simple judgment steps on the single-chip microcomputer, which causes a great waste of single-chip microcomputer performance. According to this method, it takes a long time to adjust the LED load to the set color temperature, and the dimming change is not smooth.

[0051] Based on this, an embodiment of the present application provides a constant current sampling circuit and device. Among them, the adjustment unit receives a modulation signal and converts the modulation signal into a standard parameter. The control unit compares the standard parameter with the load parameter of the loop obtained by the sampling unit to determine the conduction and closing of the switch tube, thereby realizing the constant current of the constant current sampling circuit under the current standard parameter. The adjustment unit obtains different modulation signals, thereby controlling the gain change of the control unit under different standard parameters, and then simulating dimming in the constant current circuit, adjusting the brightness of the LED, and adjusting the color temperature of the LED load in real time. It can be applied to the cathode end of the constant current device. And using simple components, the constant current of the power supply is realized, reducing the cost of the device.

[0052] Example

[0053] On the one hand, see Figure 1 This embodiment provides a constant current sampling circuit 100, including: a load unit 101, a sampling unit 102, and a control unit 103; the control unit 103 includes a switch tube 301 and a main control module 302; the main control module 302 is connected to the switch tube 301 and the sampling unit 102 respectively. The sampling unit 102 is arranged at the ground end of the load unit 101.

[0054] The load unit 101 is used to connect to the first power supply; the load unit 101 forms a loop with the switch tube 301 and the sampling unit 102 in sequence. When the switch tube 301 is turned on, the load unit 101 and the sampling unit 102 form a closed current loop, and at this time, the sampling unit 102 obtains the current in the current loop.

[0055] In this embodiment, the load unit 101 includes an LED device and an inductive element. The LED device and the inductive element are connected in series. When the switch tube 301 is turned off, the inductive element in the load unit 101 is used to maintain the device current in the load unit 101. The sampling unit 102 collects the device current.

[0056] It can be understood that when the switch tube 301 is turned on, the first power supply provides a power supply voltage to the load unit 101. At this time, the current passes through the load unit 101, the switch tube 301, and the sampling resistor to the ground. The sampling unit 102 obtains the current in the loop. When the switch tube 301 is turned off, the inductive element in the load unit 101 begins to prevent the current in the loop from changing instantaneously to maintain the current of the light-emitting device in the load unit 101. At this time, the sampling unit 102 obtains the device current. When the device current is less than the reference voltage, the switch tube 301 is turned off, and the current passes through the first power supply, the load unit 101, the switch tube 301, and the sampling resistor to the ground. The load parameter monitored by the sampling resistor is the voltage of the sampling resistor in this embodiment. When the load parameter is greater than the standard parameter, the switch tube 301 is disconnected, and the load parameter monitored by the sampling resistor begins to decrease until the load parameter is less than the standard parameter, and the switch tube 301 is closed. In this way, the LED constant current can be achieved.

[0057] In this embodiment, the sampling unit 102 is used to obtain the load parameter in the loop. The control unit 103 is based on the load parameter in the loop. In an achievable solution, the load parameter can be a voltage parameter. When the voltage parameter is less than the reference voltage, the main control module 302 outputs a control signal, that is, the second control signal, to turn off the switch tube 301. When the voltage parameter is greater than the reference voltage, the main control module 302 outputs a control signal, that is, the second control signal, to turn off the switch tube 301.

[0058] In this example, see Figure 2 , the adjustment unit 104 is connected to the main control module 302. The adjustment unit 104 is used to receive the modulation signal and convert the modulation signal into a standard parameter. The main control module 302 can determine the control signal according to the load parameter and the standard parameter to control the switch tube 301 to be turned on or off. When the main control module 302 outputs the first control signal, the switch tube 301 is turned on. When the main control module 302 outputs the second control signal, the switch tube 301 is turned off.

[0059] Exemplarily, after receiving the modulation signal, the dimming signal converts the modulation signal into a standard parameter. When the first power supply provides the supply voltage to the loop, the sampling unit 102 monitors the sampling current of the loop in real time and transmits the sampling current to the main control module 302 in real time.

[0060] In an achievable embodiment, the sampling unit 102 includes a sampling resistor R8, and the sampling resistor R8 can convert the sampling current of the loop into a voltage, thereby determining the voltage parameter.

[0061] The main control module 302 receives the voltage parameter and compares it with the reference voltage converted by the adjustment unit 104. If the voltage parameter is less than the reference voltage, the main control module 302 outputs a second control signal and uses the first control signal to maintain or turn on the switch tube 301. When the voltage parameter is greater than the reference voltage, the main control module 302 outputs a second control signal and uses the second control signal to turn off the switch tube 301.

[0062] In this embodiment, different standard parameters corresponding to different modulation signals are received by the adjustment unit 104. On the basis of realizing LED constant current, different standard parameters can be set to provide different judgment criteria for the load unit 101, thereby realizing the conversion of the modulation signal.

[0063] In one possible implementation, see Figure 3 , the main control module 302 includes at least one first operational amplifier unit. The output end of the sampling unit 102 is connected to the first input end of the first operational amplifier unit. The output end of the adjustment unit 104 is connected to the second input end of the first operational amplifier unit. The output end of the first operational amplifier unit is connected to the control end of the switch tube 301. Among them, the first operational amplifier unit is used to determine the control signal according to the value between the standard parameter and the load parameter to control the switch tube 301 to be turned on or off. For example, when the load parameter is greater than the standard parameter, the main control module 302 outputs a first control signal. When the load parameter is less than the standard parameter, the main control module 302 outputs a second control signal.

[0064] In another possible implementation, see Figure 4, the number of the adjustment units 104 can be multiple, and the input of multiple modulation signals can be realized. Correspondingly, the number of the adjustment units 104 corresponds to the number of the control units 103 and the load units 101. For example, when the number of the adjustment units 104 is 2, dual-channel modulation signals can be received, and then the modulation signals are converted into corresponding reference voltages according to the above two adjustment units 104. The first operational amplifier unit corresponds to it, and the number can also be two, and its input end receives different reference voltages respectively, and then constructs different loops with the control unit 103 and the load unit 101. In another feasible embodiment, the number of the first operational amplifier unit can remain unchanged, as long as the judgment of multiple signals can be completed.

[0065] In this embodiment, please refer to Figure 5 The first operational amplifier unit includes a first operational amplifier and a first input resistor R4; the first input end of the first operational amplifier U1 is connected to the output end of the sampling unit 102 through the first input resistor R4; the second input end of the first operational amplifier U1 is connected to the output end of the adjustment unit 104; the output end of the first operational amplifier U1 is connected to the control end of the switch tube 301.

[0066] In another possible embodiment, please refer to Figure 6 The first operational amplifier unit further includes a pull-up resistor R9 and a first diode D1. The second power supply is respectively connected to the cathode of the first diode D1 and one end of the pull-up resistor R9, and the anode of the first diode D1 is connected to the second input end of the first operational amplifier U1. The other end of the pull-up resistor R9 is connected to the first input end of the first operational amplifier U1. Among them, the first diode D1 can be a voltage stabilizing diode.

[0067] In this embodiment, the first operational amplifier unit further includes a filter component. The filter component may be an RC filter component, including a filter resistor R10, a second capacitor C2, and a third diode D3. The filter resistor R10, the second capacitor C2, and the third diode D3 are all connected in parallel. One end of the filter component is grounded, and the other end is connected to the positive electrode of the second diode D2.

[0068] In a feasible implementation, the main control module 302 further includes a second operational amplifier unit. The input end of the first operational amplifier unit is connected to the output end of the sampling unit 102. The input end of the second operational amplifier unit is connected to the first input end of the first operational amplifier unit. The second operational amplifier unit is used to amplify the load parameter.

[0069] In this embodiment, please refer to Figure 7The second operational amplifier unit includes a first feedback resistor R5, a second operational amplifier U2, a second input resistor R6 and a third input resistor R7; the first input end of the second operational amplifier U2 is connected to the output end of the second operational amplifier U2 through the first feedback resistor R5; the first input end of the second operational amplifier U2 is also connected to one end of the sampling unit 102 through the second input resistor R6; the second input end of the second operational amplifier U2 is connected to the other end of the sampling unit 102 through the third input resistor R7.

[0070] The second operational amplifier unit further includes a first grounding resistor C3 and a second grounding resistor C4, wherein the first grounding resistor C3 and the second grounding resistor C4 are respectively arranged at the first input terminal and the second input terminal of the second operational amplifier unit.

[0071] In this embodiment, please refer to Figure 8 The adjustment unit 104 includes a first resistor R1, a second resistor R2, a third resistor R3 and a first capacitor C1; one end of the first resistor R1 serves as an input end of the adjustment unit 104; the other end of the first resistor R1 is respectively connected to one end of the second resistor R2, one end of the third resistor R3 and one end of the first capacitor C1; the other end of the second resistor R2 is connected to the other end of the first capacitor C1 and is grounded; the other end of the third resistor R3 is connected to the control unit 103.

[0072] In an achievable embodiment, the modulation signal received by the adjustment unit 104 may be a PWM signal. By adjusting different duty cycles of the PWM signal, the PWM signals corresponding to different duty cycles are converted into different analog quantities by the adjustment unit 104 to determine a reference voltage. The reference voltage is used as a reference voltage of the first operational amplifier unit to compare the load parameters obtained by the sampling unit 102. Among them, different duty cycles can further adjust the current of the LED device in the load unit 101.

[0073] Furthermore, the switch tube 301 includes a switch tube and a regulating submodule; the switch tube Q1 is connected in series in the loop, and the control end of the switch tube Q1 is respectively connected to the output end of the first operational amplifier unit and the regulating submodule; the regulating submodule is used to connect to the first power supply to adjust the shutdown time of the switch tube.

[0074] In this embodiment, please refer to Fig. 9 The regulating submodule includes a first voltage stabilizing diode DZ1 and a fourth resistor R9; the anode of the first voltage stabilizing diode DZ1 is connected to the regulating unit 104; the cathode of the first voltage stabilizing diode DZ1 is connected to one end of the fourth resistor R9; the other end of the fourth resistor R9 is respectively connected to the output end of the first operational amplifier unit and the control end of the switch tube Q1. Based on the above regulating submodule, the on / off frequency of the switch tube Q1 can be better adjusted.

[0075] Please refer to Fig.10 In order to better adjust the on / off frequency of the switch tube Q1, a driving module can also be set at the control end of the switch tube, and the driving module includes a fifth resistor R10, a sixth resistor R11 and a second diode D2. The fifth resistor R10 is connected in series to the control end of the switch tube and the first end of the switch tube, and the second end of the switch tube is connected to the load unit 101. The control end of the switch tube is connected to the output end of the first operational amplifier unit through the sixth resistor R11. The second diode D2 is connected in parallel with the sixth resistor R11.

[0076] In a feasible solution, the first operational amplifier unit and the second operational amplifier unit in the main control module 302 can be integrated into a single chip microcomputer, thereby improving the integration of the constant current sampling circuit 100 and reducing the circuit area. The dimming signal can also be converted into a PWM signal by the single chip microcomputer. An optical coupler device can also be set at the input end of the dimming signal to isolate the signal interference at the front end of the single chip microcomputer. Accurate input of the signal is guaranteed.

[0077] In summary, please refer to Fig.11 , a constant current sampling circuit is provided in an embodiment of the utility model. The constant current sampling circuit includes: a load unit, a sampling unit, a control unit and an adjustment unit. The adjustment unit is used to receive a modulation signal and convert the modulation signal into a standard parameter. The control unit compares the standard parameter with the load parameter of the loop obtained by the sampling unit to determine the on and off of the switch tube, thereby realizing the constant current of the constant current sampling circuit under the current standard parameters. The adjustment unit obtains different modulation signals, thereby controlling the gain change of the control unit under different standard parameters, and then simulating dimming in the constant current circuit, adjusting the brightness of the LED, and adjusting the color temperature of the LED load in real time. The utility model can be applied to the cathode end of the constant current device, and uses simple components to realize the constant current of the power supply, thereby reducing the cost of the device.

[0078] In a second aspect, the utility model further provides a constant current sampling device, comprising any constant current sampling circuit of the above-mentioned first aspect.

[0079] The constant current sampling device provided by the embodiment of the utility model includes all the technical effects and technical means of the constant current sampling circuit provided by the first aspect above. Dimming is simulated in the constant current circuit to adjust the brightness of the LED and adjust the color temperature of the LED load in real time. The utility model can be applied to the cathode end of the constant current device and realize the constant current of the power supply by using simple components, thereby reducing the device cost.

[0080] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A constant current sampling circuit, characterized in that: include: A load unit, a sampling unit and a control unit; the control unit includes a switch tube and a main control module; the main control module is connected to the switch tube and the sampling unit respectively; The load unit is used to connect to the first power supply; the load unit forms a loop with the switch tube and the sampling unit in sequence; wherein the load unit includes an inductive element and an LED device; The sampling unit is used to obtain the load parameters in the loop; The main control module is used to determine a control signal according to the load parameter to control the switch tube to be turned on or off; When the main control module outputs the first control signal, the switch tube is turned on; When the main control module outputs the second control signal, the switch tube is turned off; The sampling unit is arranged at the grounding end of the load unit.

2. The constant current sampling circuit according to claim 1, characterized in that: The constant current sampling circuit further comprises at least one regulating unit, and the regulating unit is connected to the main control module; The adjustment unit is used to receive the modulation signal and convert the modulation signal into a standard parameter; When the load parameter is greater than the standard parameter, the main control module outputs a first control signal; When the load parameter is less than the standard parameter, the main control module outputs a second control signal.

3. The constant current sampling circuit according to claim 2, characterized in that: The main control module at least includes a first operational amplifier unit; the output end of the sampling unit is connected to the first input end of the first operational amplifier unit; the output end of the adjustment unit is connected to the second input end of the first operational amplifier unit; the output end of the first operational amplifier unit is connected to the control end of the switch tube; Wherein, the first operational amplifier unit is used to determine a control signal according to a value between the standard parameter and the load parameter to control the switch tube to be turned on or off; When the load parameter is greater than the standard parameter, the main control module outputs a first control signal; When the load parameter is less than the standard parameter, the main control module outputs a second control signal.

4. The constant current sampling circuit according to claim 3, characterized in that: The main control module also includes a second operational amplifier unit; the input end of the first operational amplifier unit is connected to the output end of the sampling unit; the input end of the second operational amplifier unit is connected to the first input end of the first operational amplifier unit; wherein the second operational amplifier unit is used to amplify the load parameter.

5. The constant current sampling circuit according to claim 2, characterized in that: The adjustment unit includes a first resistor, a second resistor, a third resistor and a first capacitor; one end of the first resistor serves as an input end of the adjustment unit; the other end of the first resistor is respectively connected to one end of the second resistor, one end of the third resistor and one end of the first capacitor; the other end of the second resistor is connected to the other end of the first capacitor and is grounded; the other end of the third resistor is connected to the control unit.

6. The constant current sampling circuit according to claim 3, characterized in that: The first operational amplifier unit includes a first operational amplifier and a first input resistor; the first input end of the first operational amplifier is connected to the output end of the sampling unit through the first input resistor; the second input end of the first operational amplifier is connected to the output end of the adjustment unit; the output end of the first operational amplifier is connected to the control end of the switch tube.

7. The constant current sampling circuit according to claim 4, characterized in that: The second operational amplifier unit includes a first feedback resistor, a second operational amplifier, a second input resistor and a third input resistor; the first input end of the second operational amplifier is connected to the output end of the second operational amplifier through the first feedback resistor; the first input end of the second operational amplifier is also connected to one end of the sampling unit through the second input resistor; the second input end of the second operational amplifier is connected to the other end of the sampling unit through the third input resistor.

8. The constant current sampling circuit according to claim 3, characterized in that: The switch tube includes a switch tube and a regulating submodule; the switch tube is connected in series in the loop, and the control end of the switch tube is respectively connected to the output end of the first operational amplifier unit and the regulating submodule; the regulating submodule is used to connect to the first power supply to adjust the shutdown time of the switch tube.

9. The constant current sampling circuit according to claim 8, characterized in that: The regulating submodule includes a first voltage stabilizing diode and a fourth resistor; the anode of the first voltage stabilizing diode is connected to the regulating unit; the cathode of the first voltage stabilizing diode is connected to one end of the fourth resistor; the other end of the fourth resistor is respectively connected to the output end of the first operational amplifier unit and the control end of the switching tube.

10. A constant current sampling device, characterized in that: The constant current sampling circuit comprises any one of claims 1 to 9.

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