An adjustable constant current power supply and current regulation method

Abstract

The present invention discloses an adjustable constant current power supply and a current regulation method, comprising: an output circuit and a regulation circuit; the output circuit comprises an operational amplifier and a first NMOS tube; the positive input end of the operational amplifier is connected to a first reference voltage; the negative input end of the operational amplifier is connected to the source of the first NMOS tube; the output end of the operational amplifier is connected to the gate of the first NMOS tube; the drain of the first NMOS tube is connected to an external load; the regulation circuit is connected in series with the output circuit, and the regulation circuit is connected to a ground wire; the regulation circuit comprises a basic load resistor, a resistor array and a regulation component; the resistor array comprises at least one regulation load resistor and at least one first control structure, each of the regulation load resistors is respectively connected to the corresponding first control structure, and the regulation load resistor is connected in parallel with the basic load resistor.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to an adjustable constant current power supply and a current regulation method. Background Art

[0002] Constant current power supplies are widely used as electronic load tests. During the test, due to different use environments and conditions, a variety of different test currents are required for more comprehensive testing. Traditional constant current power supplies can only output fixed current values ​​when used. When other current values ​​need to be applied, the constant current power supply needs to be replaced, and frequent replacement may cause wrong wiring or misoperation to cause short circuits, causing damage to the constant current power supply. Summary of the invention

[0003] The invention provides an adjustable constant current power supply and a current regulating method to realize the adjustable output of the constant current power supply.

[0004] In a first aspect, the present invention provides an adjustable constant current power supply, comprising: an output circuit and a regulating circuit;

[0005] The output circuit includes an operational amplifier and a first NMOS tube; the positive input terminal of the operational amplifier is connected to a first reference voltage; the negative input terminal of the operational amplifier is connected to a source of the first NMOS tube; the output terminal of the operational amplifier is connected to a gate of the first NMOS tube; and the drain of the first NMOS tube is connected to an external load;

[0006] The regulating circuit is connected in series with the output circuit, and the regulating circuit is connected to the ground line; the regulating circuit includes a basic load resistor, a resistor array and an regulating component; the resistor array includes at least one regulating load resistor and at least one first control structure, each of the regulating load resistors is respectively connected to the corresponding first control structure, and the regulating load resistor is connected in parallel with the basic load resistor; the regulating component is used to adjust the first control structure corresponding to each of the regulating load resistors to adjust the overall resistance value of the output circuit.

[0007] Preferably, the adjustment component comprises:

[0008] A controller and a microcontroller unit; the controller is connected to the microcontroller unit to send a first control signal to the microcontroller unit; the microcontroller unit is respectively connected to each of the first control structures in the resistor array through each output interface to send a second control signal to the first control structure through the output interface; each of the first control structures responds to the second control signal to turn on or off the connection state of the adjustable load resistor.

[0009] Preferably, the first control structure includes:

[0010] A second NMOS tube and a PMOS tube;

[0011] The gate of the second NMOS tube is connected to the output interface of the micro control unit, the source of the second NMOS tube is connected to the ground line, and the drain of the second NMOS tube is connected to the gate of the PMOS tube; the drain of the PMOS tube is connected to the output circuit; the source of the PMOS tube is connected to the first end of the adjustable load resistor; the second end of the adjustable load resistor is connected to the ground line; a jumper resistor is connected between the gate and drain of the PMOS tube.

[0012] Preferably, the controller comprises:

[0013] at least one second control structure, each of the second control structures corresponds to one of the first control structures; each of the second control structures is connected to an input interface of the micro control unit;

[0014] The second control structure includes a switch closer, a switch resistor and a capacitor; a first end of the switch closer is connected to a ground line, and a second end of the switch closer is connected to the switch resistor; a first end of the capacitor is connected to a ground line, and a second end of the capacitor is connected to the switch resistor;

[0015] When the switch closer is closed, the second control structure sends the first control signal to the input interface of the micro control unit.

[0016] Preferably, the adjustable constant current power supply further includes: a protection circuit;

[0017] The protection circuit includes a follower, a comparator and a third NMOS tube; the positive input end of the comparator is connected to the first end of the basic load resistor through the follower, and receives the sampling voltage output by the operational amplifier; the first end of the basic load resistor is connected to the first end of the sampling resistor, and the second end of the sampling resistor is connected to the ground wire;

[0018] The negative input terminal of the comparator is connected to the second reference voltage; the output terminal of the comparator is connected to the gate of the third NMOS tube; the source of the third NMOS tube is connected to the ground line; the drain of the third NMOS tube is connected to the gate of the first NMOS tube;

[0019] When the sampling voltage is less than the second reference voltage, the output terminal of the comparator outputs a low level signal to disconnect the third NMOS tube;

[0020] When the sampling voltage is greater than the second reference voltage, the output terminal of the comparator outputs a high level signal to turn on the third NMOS tube; when the third NMOS tube is turned on, the first NMOS tube is turned off.

[0021] In a second aspect, the present invention provides a current regulation method, which is applied to the adjustable constant current power supply according to any one of claims 1 to 5, comprising:

[0022] Determining a control signal using a regulating component according to a predetermined target current value;

[0023] Using the control signal, adjusting a first control structure in the resistor array so that the connection state of the load resistor corresponding to the first control structure is turned on or off;

[0024] When the connection state of the adjustment load resistor is on, the adjustment load resistor is connected in parallel with the basic load resistor to adjust the overall resistance value of the output circuit.

[0025] Preferably, determining the control signal by using the regulating component according to the predetermined target current value includes:

[0026] Determining a target resistance value according to the target current value;

[0027] The control signal is determined according to the target resistance value.

[0028] Preferably, the regulating component includes a controller and a microcontroller unit, the control signal includes a first control signal and a second control signal, and the determining the control signal using the regulating component includes:

[0029] The controller sends a first control signal to an input interface of the micro control unit based on the received external operation;

[0030] The micro control unit sends the second control signal to the first control structure using a specific output interface according to the first control signal.

[0031] Preferably, the first control structure includes a second NMOS transistor and a PMOS transistor, and the use of the control signal to adjust the first control structure in the resistor array so that the connection state of the load resistor corresponding to the first control structure is turned on or off includes:

[0032] When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first high level signal, the second NMOS tube is turned on, the PMOS tube is turned on, and the connection state of the adjustable load resistor is turned on;

[0033] When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first low level signal, the second NMOS tube is disconnected, the PMOS tube is disconnected, and the connection state of the adjustable load resistor is disconnected.

[0034] When the adjustable constant current power supply includes a protection circuit, the method further includes:

[0035] When the sampling voltage in the protection circuit is less than the second reference voltage, the output terminal of the comparator of the sampling circuit outputs a low level signal to disconnect the third NMOS tube of the sampling circuit;

[0036] When the sampling voltage is greater than the second reference voltage, the output terminal of the comparator outputs a high level signal to turn on the third NMOS tube.

[0037] The present invention provides an adjustable constant current power supply and a current regulation method. Through a circuit of a constant current power supply with a new structure, the regulation circuit of the constant current power supply can control different regulated load resistors to be connected in parallel with a basic load resistor, thereby controlling the overall resistance value of the constant current power supply and realizing the regulation function of the constant current power supply.

[0038] The further effects of the above-mentioned non-conventional preferred manner will be described below in conjunction with specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the existing technical solutions, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1 A schematic diagram of the structure of an adjustable constant current power supply circuit provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the structure of a resistor array in an adjustable constant current power supply provided by an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the connection relationship between an adjusting component and a resistor array in an adjustable constant current power supply provided by an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of a second control structure in an adjustable constant current power supply provided by an embodiment of the present invention;

[0044] Figure 5A schematic diagram of the structure of a protection circuit in an adjustable constant current power supply provided by an embodiment of the present invention;

[0045] Figure 6 A schematic flow chart of a current regulation method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0047] Constant current power supplies are widely used for electronic load testing. During the testing process, different test currents are required for different test environments and conditions to conduct more comprehensive testing. However, the existing constant current power supplies usually can only output a fixed current value because the voltage V applied to the external load and the resistance R of the load resistor are fixed. According to Ohm's law, the output current I=V / R. When other current values ​​need to be applied, the constant current power supply needs to be replaced, and frequent replacement may cause short circuits due to wrong wiring or misoperation, causing damage to the constant current power supply.

[0048] In view of this, the present invention provides an adjustable constant current power supply. Figure 1 01 is a specific embodiment of the adjustable constant current power supply provided by the present invention. In this embodiment, the adjustable constant current power supply includes: an output circuit 01 and a regulating circuit 02.

[0049] The output circuit 01 includes an operational amplifier 11 and a first NMOS transistor Q1. The positive input terminal of the operational amplifier 11 is connected to a first reference voltage VREF1; the negative input terminal of the operational amplifier 11 is connected to the source of the first NMOS transistor Q1; the output terminal of the operational amplifier 11 is connected to the gate of the first NMOS transistor Q1. The drain of the first NMOS transistor Q1 is connected to an external load and an external voltage VCC.

[0050] The regulating circuit 02 is connected in series with the output circuit, and the regulating circuit 02 is connected to the ground line; the regulating circuit 02 includes a basic load resistor R1, a resistor array 21 and a regulating component 22.

[0051] The resistor array 21 includes at least one load adjustment resistor and at least one first control structure 211. Figure 2 As shown in FIG. 1 , it is a schematic diagram of the structure of the resistor array 21 in this embodiment. Figure 2 In the example of , the resistor array 21 includes two adjustable load resistors, namely R2 and R3. The resistance values ​​of the adjustable load resistors can be the same or different. Each of the adjustable load resistors is connected to the corresponding first control structure 211. The specific circuit structure of each first control structure 211 can be the same.

[0052] exist Figure 2 In the embodiment, the first control structure 211 corresponding to the load resistor R2 is taken as an example for description. The first control structure 211 includes a second NMOS tube Q2 and a PMOS tube P1. The gate of the second NMOS tube Q2 is connected to the adjustment component 22, the source of the second NMOS tube Q2 is connected to the ground line, and the drain of the second NMOS tube Q2 is connected to the gate of the PMOS tube P1. The drain of the PMOS tube P1 is connected to the output circuit 01, and the source of the PMOS tube P1 is connected to the first end of the load resistor R2. The second end of the load resistor R2 is connected to the ground line. A jumper resistor Rn is connected between the gate and the drain of the PMOS tube P1.

[0053] Each of the adjustment load resistors is connected in parallel with the basic load resistor R1. The adjustment component 22 is used to adjust the first control structure 211 corresponding to each of the adjustment load resistors so that the adjustment load resistor is connected to the output circuit 01 or disconnected from the output circuit 01, thereby adjusting the overall resistance value of the output circuit, that is, the overall resistance value after each of the adjustment load resistors is connected in parallel with the basic load resistor R1.

[0054] Since the overall resistance value of the constant current power supply is adjustable, the current value output by the constant current power supply can be changed by adjusting the overall resistance value of the constant current power supply when the first reference voltage VREF1 is constant. Therefore, the adjustable constant current power supply described in this embodiment can provide a variety of different current values.

[0055] During the use of the constant current power supply, the resistor array 21 can be controlled by the adjustment component 22. Specifically, the load resistor can be controlled to be connected to the output circuit 01 or disconnected from the output circuit 01. In this embodiment, the connection relationship between the adjustment component 22 and the resistor array 21 is as follows: Figure 3 The regulating component 22 includes a controller 221 and a microcontroller unit 222 (MCU). The specific structure of the controller 221 is as follows: Figure 4 As shown. The controller 221 includes at least one second control structure 2211. The second control structure 2211 usually corresponds to the first control structure 211 one by one; it can also be said that the second control structure 2211 corresponds to the adjustment load resistor one by one and is dedicated to controlling a specific adjustment load resistor. Figure 4In the illustrated case, the controller 221 includes two mutually independent second control structures 2211. The specific circuit structure of each second control structure 2211 can be the same.

[0056] exist Figure 4 In the case shown, any second control structure 2211 may include a switch closure key, a switch resistor Rk and a capacitor C. The first end of the switch closure key is connected to the ground line, and the second end of the switch closure key is connected to the switch resistor Rk. The first end of the capacitor C is connected to the ground line, and the second end of the capacitor C is connected to the switch resistor Rk. Each second control structure 2211 is respectively connected to an input interface of the micro control unit 222. Figure 4 In the embodiment, the two second control structures 2211 are respectively connected to the input interface 1 and the input interface 2 of the micro control unit 222 .

[0057] The user operates the controller 221, that is, operates any switch closer key in the second control structure 2211 to open or close. When the switch closer key in the second control structure 2211 is operated, the second control structure 2211 will send a first control signal to the input interface of the micro control unit 222. Through the internal calculation of the micro control unit 222, the second control signal can be determined according to the first control signal. The second control signal is output by a specific output interface in the micro control unit 222, and the specific output interface is connected to the first control structure 211 corresponding to the second control structure 2211. Specifically, the output interface will be connected to the gate of the second NMOS tube Q2 in the first control structure 211. In other words, the second control structure 2211 can communicate with the corresponding first control structure 211 through the micro control unit 222.

[0058] For example, when the switch closer key of a second control structure 2211 is closed, the micro control unit 222 will send a high-level second control signal to the corresponding first control structure 211 through the output interface, which will be applied to the gate of the second NMOS tube Q2. The second NMOS tube Q2 is turned on after the gate receives the high-level signal. After the second NMOS tube Q2 is turned on, the gate of the PMOS tube P1 will be connected to the ground line and thus be at a low potential. When the gate of the PMOS tube is at a low potential, the PMOS tube will also be turned on, so that the regulated load resistor corresponding to the first control structure 211 is connected to the output circuit 01 in parallel with the basic load resistor R1.

[0059] On the contrary, when the switch closer key of the second control structure 2211 is disconnected, based on the same control principle, the gate of the second NMOS transistor Q1 receives a low-level signal, and the second NMOS transistor Q1 is disconnected. At this time, the PMOS transistor P1 will also be in an off state, so that the adjustment load resistor corresponding to the first control structure 211 is disconnected from the output circuit 01. Therefore, in this embodiment, the parallel relationship between the basic load resistor R1 and the adjustment load resistor can be adjusted by controlling the connection or disconnection of the adjustment load resistor with the output circuit 01, so as to adjust the overall resistance value of the constant current power supply.

[0060] In addition, the adjustable constant current power supply in this embodiment may also include: Figure 5 The protection circuit 03 shown. The protection circuit 03 includes a comparator 31, a follower 32 and a third NMOS tube Q3. The positive input terminal of the comparator 31 is connected to the first end of the basic load resistor R1 through the follower 32, and receives the sampling voltage VREF1' output by the operational amplifier 11. In addition, the first end of the basic load resistor R1 is also connected to the first end of a sampling resistor R0 with a smaller resistance value, and the second end of the sampling resistor R0 is connected to the ground line. Among them, the follower 32 can play the role of isolation and following, reducing the influence of the sampling circuit on the load current. The negative input terminal of the comparator 31 is connected to the second reference voltage VREF2, and the second reference voltage VREF2 can be a voltage threshold set in advance in an adjustable constant current power supply. The output terminal of the comparator 31 is connected to the gate of the third NMOS tube Q3, and the drain of the third NMOS tube is connected to the gate of the first NMOS tube Q1.

[0061] In this embodiment, when the sampling voltage VREF1' is greater than the second reference voltage VREF2, it means that the first reference voltage VREF1 is higher than the normal value range. At this time, after the sampling voltage VREF1' and the second reference voltage VREF2 are input into the comparator 31 for comparison, the output end of the comparator 31 will output a high level signal. The gate of the third NMOS tube Q3 is turned on after receiving the high level signal, so that the gate of the first NMOS tube Q1 is connected to the ground line and is at a low potential. At this time, the first NMOS tube Q1 is disconnected, cutting off the output circuit 01. That is, when the first reference voltage VREF1 is higher than the normal value range, the output circuit 01 will be automatically cut off, thereby protecting the circuit of the adjustable constant current power supply.

[0062] On the contrary, when the sampling voltage VREF1' is less than the second reference voltage VREF2, the output terminal of the comparator 31 will output a low level signal, so that the third NMOS transistor Q3 is turned off and the first NMOS transistor Q1 is turned on, and the adjustable constant current power supply works normally.

[0063] It can be seen from the above technical solution that the beneficial effect of this embodiment is: through the circuit of the constant current power supply with a new structure, the output current of the constant current power supply can be adjusted, and it no longer outputs only a fixed current value, thereby avoiding frequent replacement of the constant current power supply during use, and avoiding damage caused by misoperation during replacement.

[0064] like Figure 6 As shown in FIG. 1 , a specific embodiment of a current regulation method according to the present invention is shown. The method according to this embodiment is applied to Figures 1 to 5 The adjustable constant current power supply. In this embodiment, it is assumed that the resistance value of the basic load resistor in the adjustable constant current power supply is R1=10Ω, the resistance values ​​of the four adjustable load resistors in the resistor array are R2=2.5Ω, R3=5Ω, R4=10Ω, R5=20Ω, the first reference voltage value VREF1=10V, and the resistance value of the sampling resistor R0 can be ignored. In the initial state, all adjustable load resistors are disconnected from the output circuit, then the overall resistance value of the constant current power supply is equal to 10Ω of the basic load resistor. At this time, the output current I0 of the constant current power supply is: I0=VREF1 / R1=1A. If you want to adjust the output current of the constant current power supply so that the current value of its output current becomes 5A, the adjustment can be achieved by the method in this embodiment. The method described in this embodiment includes:

[0065] Step 601: Determine a control signal using a regulating component according to a predetermined target current value.

[0066] In this embodiment, the target resistance value can be determined according to the target current value. The target current value I1 is 5A. Then the target resistance value R' of the constant current power supply can be determined as R'=VREF1 / I1=2Ω. In other words, if the overall resistance value of the constant current power supply is adjusted to the target resistance value R' through adjustment, the constant current power supply can output the target current value I1.

[0067] When the resistance value of the basic load resistor R1=10Ω, according to the parallel resistor resistance calculation formula, it can be known that only by connecting a resistor with a resistance value of 2.5Ω in parallel with the basic load resistor R1, the overall resistance value of the constant current power supply can be adjusted to 2Ω, that is, adjusted to the target resistance value R'. The resistance value of the adjustable load resistor R2 is exactly 2.5Ω. Then, it is only necessary to connect the adjustable load resistor R2 to the output circuit in parallel with the basic load resistor R1 to achieve the adjustment purpose in this embodiment.

[0068] In this case, in this embodiment, the control signal can be determined according to the target resistance value. Specifically, the control signal can be determined by the adjustment component described above. The adjustment component includes a controller and a micro control unit, and the control signal includes a first control signal and a second control signal. Then, the controller can be used to send a first control signal to an input interface of the micro control unit based on the received external operation. Then, the micro control unit is used to send the second control signal to the first control structure using a specific output interface according to the first control signal.

[0069] That is, when the user needs to connect the adjustable load resistor R2 to the output circuit, the user can operate the second control structure corresponding to the adjustable load resistor R2 in a targeted manner, so that the switch closer in the second control structure changes from open to closed. After the switch closer is closed, the second control structure sends a first control signal to the input interface of the micro control unit. Through the internal calculation of the micro control unit, the second control signal can be determined according to the first control signal. The second control signal is specifically a high level signal. The second control signal is output by a specific output interface in the micro control unit, and the specific output interface is connected to the first control structure corresponding to the second control structure.

[0070] Step 602: Utilize the control signal to adjust a first control structure in the resistor array so that the connection state of the load resistor corresponding to the first control structure is turned on or off.

[0071] The first control structure is also as described in the above embodiment, including a second NMOS tube and a PMOS tube. When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first high level signal, the second NMOS tube is turned on, the PMOS tube is turned on, and the connection state of the adjustable load resistor is turned on. When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first low level signal, the second NMOS tube is turned off, the PMOS tube is turned off, and the connection state of the adjustable load resistor is turned off.

[0072] In this embodiment, the high-level second control signal output by the microcontroller unit is applied to the gate of the second NMOS tube of the first control structure. The second NMOS tube Q2 is turned on after the gate receives the high-level signal. After the second NMOS tube Q2 is turned on, the gate of the PMOS tube P1 will be connected to the ground line and thus be at a low potential. When the gate of the PMOS tube is at a low potential, the PMOS tube will also be turned on, so that the adjustment load resistor R2 is connected to the output circuit in parallel with the basic load resistor R1.

[0073] Step 603: When the connection state of the adjustable load resistor is on, the adjustable load resistor is connected in parallel with the basic load resistor to adjust the overall resistance value of the output circuit.

[0074] After the adjustable load resistor R2 is connected to the output circuit in parallel with the basic load resistor R1, the overall resistance value of the constant current power supply is equal to the resistance value of the basic load resistor R1 and the adjustable load resistor R2 in parallel, that is, 2Ω. At this time, the current value output by the constant current power supply can reach the above-mentioned target current value.

[0075] In addition, when the above-mentioned constant current power supply includes the protection circuit described in the above-mentioned embodiment, the method in this embodiment may further include:

[0076] Step 604: When the sampling voltage in the protection circuit is less than the second reference voltage, the output terminal of the comparator of the sampling circuit outputs a low level signal to disconnect the third NMOS transistor of the sampling circuit.

[0077] Step 605: When the sampling voltage is greater than the second reference voltage, the output terminal of the comparator outputs a high level signal to turn on the third NMOS transistor.

[0078] That is to say, when the sampling voltage is greater than the second reference voltage, it means that the first reference voltage is higher than the normal value range. At this time, after the sampling voltage and the second reference voltage are input into the comparator for comparison, the output end of the comparator will output a high level signal. The gate of the third NMOS tube is turned on after receiving the high level signal, so that the gate of the first NMOS tube is connected to the ground wire and is at a low potential. At this time, the first NMOS tube is disconnected, cutting off the output circuit. That is, when the first reference voltage is higher than the normal value range, the output circuit will automatically cut off, thereby protecting the circuit of the adjustable constant current power supply. On the contrary, when the sampling voltage is less than the second reference voltage, the output end of the comparator will output a low level signal, so that the third NMOS tube is disconnected, the first NMOS tube is turned on, and the adjustable constant current power supply works normally.

[0079] Those skilled in the art will appreciate that the embodiments of the present invention may be provided as methods or computer program products. Therefore, the present invention may be implemented in the form of a complete hardware embodiment, a complete software embodiment, or a combination of software and hardware.

[0080] The various embodiments of the present invention are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0081] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0082] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An adjustable constant current power supply, characterized in that: include: Output circuit, regulation circuit and protection circuit; The output circuit includes an operational amplifier and a first NMOS tube; the positive input terminal of the operational amplifier is connected to a first reference voltage; the negative input terminal of the operational amplifier is connected to a source of the first NMOS tube; the output terminal of the operational amplifier is connected to a gate of the first NMOS tube; and the drain of the first NMOS tube is connected to an external load; The regulating circuit is connected in series with the output circuit, and the regulating circuit is connected to the ground wire; the regulating circuit includes a basic load resistor, a resistor array and an regulating component; the resistor array includes at least one regulating load resistor and at least one first control structure, each regulating load resistor is connected to the corresponding first control structure, and the regulating load resistor is connected in parallel with the basic load resistor; the regulating component is used to adjust the first control structure corresponding to each regulating load resistor to adjust the overall resistance value of the output circuit; The protection circuit includes a follower, a comparator and a third NMOS tube; the positive input end of the comparator is connected to the first end of the basic load resistor through the follower, and receives the sampling voltage output by the operational amplifier; the first end of the basic load resistor is connected to the first end of the sampling resistor, and the second end of the sampling resistor is connected to the ground wire; The negative input terminal of the comparator is connected to the second reference voltage; the output terminal of the comparator is connected to the gate of the third NMOS tube; the source of the third NMOS tube is connected to the ground line; the drain of the third NMOS tube is connected to the gate of the first NMOS tube; the second reference voltage is a voltage threshold set in advance in the adjustable constant current power supply; When the sampling voltage is less than the second reference voltage, the output terminal of the comparator outputs a low level signal to disconnect the third NMOS tube, turn on the first NMOS tube, and the adjustable constant current power supply works normally; When the sampling voltage is greater than the second reference voltage, the output end of the comparator outputs a high-level signal to turn on the third NMOS tube; when the third NMOS tube is turned on, the gate of the first NMOS tube is connected to the ground line and is at a low potential, and the first NMOS tube is disconnected to cut off the output circuit.

2. The adjustable constant current power supply according to claim 1, characterized in that: The adjustment component comprises: A controller and a microcontroller unit; the controller is connected to the microcontroller unit to send a first control signal to the microcontroller unit; the microcontroller unit is respectively connected to each of the first control structures in the resistor array through each output interface to send a second control signal to the first control structure through the output interface; each of the first control structures responds to the second control signal to turn on or off the connection state of the adjustable load resistor.

3. The adjustable constant current power supply according to claim 2, characterized in that: The first control structure comprises: A second NMOS tube and a PMOS tube; The gate of the second NMOS tube is connected to the output interface of the micro control unit, the source of the second NMOS tube is connected to the ground line, and the drain of the second NMOS tube is connected to the gate of the PMOS tube; the drain of the PMOS tube is connected to the output circuit; the source of the PMOS tube is connected to the first end of the adjustable load resistor; the second end of the adjustable load resistor is connected to the ground line; a jumper resistor is connected between the gate and the drain of the PMOS tube.

4. The adjustable constant current power supply according to claim 2, characterized in that: The controller comprises: at least one second control structure, each of the second control structures corresponds to one of the first control structures; each of the second control structures is connected to an input interface of the micro control unit; The second control structure includes a switch closer, a switch resistor and a capacitor; a first end of the switch closer is connected to a ground line, and a second end of the switch closer is connected to the switch resistor; a first end of the capacitor is connected to a ground line, and a second end of the capacitor is connected to the switch resistor; When the switch closer is closed, the second control structure sends the first control signal to the input interface of the micro control unit.

5. A current regulation method, characterized in that: The method is applied to the adjustable constant current power supply according to any one of claims 1 to 4, comprising: Determining a control signal using a regulating component according to a predetermined target current value; Using the control signal, adjusting a first control structure in the resistor array so that the connection state of the load resistor corresponding to the first control structure is turned on or off; When the connection state of the adjustment load resistor is on, the adjustment load resistor is connected in parallel with the basic load resistor to adjust the overall resistance value of the output circuit.

6. The method according to claim 5, characterized in that: Determining the control signal by using the regulating component according to the predetermined target current value includes: Determining a target resistance value according to the target current value; The control signal is determined according to the target resistance value.

7. The method according to claim 6, characterized in that: The regulating component includes a controller and a micro control unit, the control signal includes a first control signal and a second control signal, and the using the regulating component to determine the control signal includes: The controller sends a first control signal to an input interface of the micro control unit based on the received external operation; The micro control unit sends the second control signal to the first control structure using a specific output interface according to the first control signal.

8. The method according to claim 7, characterized in that: The first control structure includes a second NMOS transistor and a PMOS transistor, and the use of the control signal to adjust the first control structure in the resistor array so that the connection state of the load resistor corresponding to the first control structure is turned on or off includes: When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first high level signal, the second NMOS tube is turned on, the PMOS tube is turned on, and the connection state of the adjustable load resistor is turned on; When the second control signal sent by the output interface of the micro control unit to the gate of the second NMOS tube is a first low level signal, the second NMOS tube is disconnected, the PMOS tube is disconnected, and the connection state of the adjustable load resistor is disconnected.

9. The method according to any one of claims 5 to 8, characterized in that: When the adjustable constant current power supply includes a protection circuit, the method further includes: When the sampling voltage in the protection circuit is less than the second reference voltage, the output terminal of the comparator of the sampling circuit outputs a low level signal to disconnect the third NMOS tube of the sampling circuit; When the sampling voltage is greater than the second reference voltage, the output terminal of the comparator outputs a high level signal to turn on the third NMOS tube.

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