Adjustable circuit, voltage stabilizer and power supply equipment

Abstract

The utility model relates to the technical field of electronic circuits, and discloses an adjustable circuit, a voltage stabilizer and power equipment, and the adjustable circuit comprises a voltage stabilization module, a current limiting module, a voltage reduction module and a protection module. The input end of the voltage stabilizing module is connected with power supply equipment, the output end of the voltage stabilizing module is connected with the first end of the current limiting module, the feedback end of the voltage stabilizing module is connected with the first end of the protection module, and the voltage stabilizing module adjusts first voltage and outputs second voltage to the current limiting module; the second end of the current-limiting module is connected with the first end of the step-down module. The second end of the step-down module is connected with the second end of the protection module. The current limiting module is used for adjusting current output by the power supply equipment; the voltage reduction module and the current limiting module are used for jointly adjusting the output voltage of the power supply equipment; the protection module is used for protecting the adjustable circuit. The adjustable circuit can adjust the output voltage and the output current of the power supply equipment, so that the power supply equipment outputs stable voltage and current, and the adjustable circuit also has an anti-backflow function and an over-current and over-voltage protection function.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technologies, and in particular, to an adjustable circuit, a voltage regulator, and a power supply device. Background Art

[0002] With the development of electronic technologies, people have higher and higher requirements for power supply quality. Unstable power supply quality will affect the normal operation of circuits. The voltage regulator was born to solve the problem of unstable power supply quality. By using a voltage regulator, the output voltage can be precisely adjusted to maintain the stable operation of the circuit. However, when using a voltage regulator, it has the following disadvantages: when the voltage regulator outputs a regulated voltage, the protection current value is determined by the voltage regulator itself and cannot be set; when the voltage regulator outputs a current limit, the output does not have a voltage regulation function. Summary of the Utility Model

[0003] In view of this, the embodiments of this application provide an adjustable circuit, a voltage regulator, and a power supply device, which can effectively solve the problems that the current limit value cannot be arbitrarily set when the traditional voltage regulator outputs a regulated voltage, and the output voltage cannot be arbitrarily set when the current limit is output.

[0004] In a first aspect, the embodiments of this application provide an adjustable circuit, including: a voltage regulation module, a current limiting module, a step-down module, and a protection module;

[0005] The input end of the voltage regulation module is used to connect to a power supply device, the output end of the voltage regulation module is connected to the first end of the current limiting module, the feedback end of the voltage regulation module is connected to the first end of the protection module, and the voltage regulation module is used to adjust the first voltage output by the power supply device and stably output a second voltage to the current limiting module;

[0006] The second end of the current limiting module is connected to the first end of the step-down module, and the second end of the step-down module is connected to the second end of the protection module;

[0007] The current limiting module is used to adjust the current output by the power supply device;

[0008] The step-down module and the current limiting module are further used to jointly adjust the second voltage to obtain a third voltage, and the third voltage is the target voltage output by the power supply device after being adjusted by the adjustable circuit;

[0009] The protection module is used to perform overcurrent and / or overvoltage protection on the adjustable circuit.

[0010] In a first possible embodiment of the first aspect, the current limiting module includes a current limiting resistor;

[0011] The first end of the current-limiting resistor is connected to the output end of the voltage-regulating module, and the second end of the current-limiting resistor is connected to the first end of the step-down module.

[0012] In the second possible embodiment of the first aspect, the step-down module includes a first diode and a second diode;

[0013] The anode of the first diode is connected to the second end of the current-limiting module, the cathode of the first diode is connected to the anode of the second diode, and the cathode of the second diode is connected to the second end of the protection module.

[0014] In the third possible embodiment of the first aspect, the protection module includes a third diode;

[0015] The cathode of the third diode is connected to the cathode of the second diode, and the anode of the third diode is connected to the feedback end of the voltage-regulating module.

[0016] In the fourth possible embodiment of the first aspect, the voltage-regulating module includes a voltage-regulating chip, a variable resistor, and a voltage-dividing resistor;

[0017] The voltage-regulating module is further configured to adjust the first voltage by adjusting the resistance value of the variable resistor to obtain the second voltage;

[0018] The input end of the voltage-regulating chip is connected to the output power supply port of the power supply device, the first end of the variable resistor is grounded, the second end of the variable resistor is respectively connected to the common end of the voltage-regulating chip, the first end of the voltage-dividing resistor, and the first end of the protection module, and the second end of the voltage-dividing resistor is respectively connected to the output end of the voltage-regulating chip and the first end of the current-limiting module.

[0019] In the fifth possible embodiment of the first aspect, the calculation formula for the target voltage is:

[0020]

[0021] In formula (1), V is the target voltage, V0 is the voltage across the voltage-dividing resistor, R2 is the resistance value of the voltage-dividing resistor, R3 is the resistance value of the variable resistor, I is the current output by the power supply device, V2 is the total voltage drop of the first diode and the second diode, and R1 is the resistance value of the current-limiting resistor.

[0022] In the sixth possible embodiment of the first aspect, the calculation formula for the current output by the power supply device is:

[0023]

[0024] In formula (2), V1 is the voltage drop of the third diode.

[0025] In a seventh possible embodiment of the first aspect, the first diode, the second diode, and the third diode are selected to have the same or different voltage drops.

[0026] In a second aspect, an embodiment of the present application provides a voltage regulator, including the adjustable circuit described above.

[0027] In a third aspect, an embodiment of the present application provides a power supply device, including the voltage regulator described above.

[0028] The embodiments of the present application have the following beneficial effects:

[0029] An adjustable circuit in this embodiment includes a voltage regulation module, a current limiting module, a voltage reduction module, and a protection module; the input end of the voltage regulation module is used to connect to a power supply device, the output end of the voltage regulation module is connected to the first end of the current limiting module, the feedback end of the voltage regulation module is connected to the first end of the protection module, and the voltage regulation module is used to adjust the first voltage output by the power supply device and stably output a second voltage to the current limiting module; the second end of the current limiting module is connected to the first end of the voltage reduction module, and the second end of the voltage reduction module is connected to the second end of the protection module; the current limiting module is used to adjust the current output by the power supply device; the voltage reduction module and the current limiting module are also used to jointly adjust the second voltage to obtain a third voltage, and the third voltage is the target voltage output by the power supply device after being adjusted by the adjustable circuit; the protection module is used to perform overcurrent and / or overvoltage protection on the adjustable circuit. Based on the above solution, the adjustable circuit can adjust the output voltage and output current of the power supply device so that the power supply device outputs stable voltage and current. At the same time, the adjustable circuit has an anti-backflow function and can prevent damage to circuit components when the voltage is reversely input. The adjustable circuit has an overcurrent or overvoltage protection function, and when there is an abnormal high voltage or current in the circuit, it can protect the circuit components from being damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 Shows a schematic structural diagram of an adjustable circuit according to an embodiment of the present application;

[0032] Figure 2 Shows a schematic circuit diagram of an adjustable circuit according to an embodiment of the present application.

[0033] MAIN ELEMENT SYMBOL DESCRIPTION:

[0034] 100 - Adjustable circuit; 110 - Voltage stabilizing module; 120 - Current limiting module; 130 - Step - down module; 140 - Protection module. Specific embodiments

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0036] The components of the embodiments of the present application described and illustrated in the drawings here are usually arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but only represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0037] In the following, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are only intended to represent specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0038] Unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as commonly understood by those of ordinary skill in the art to which the various embodiments of the present application belong. The terms (such as those defined in a general - use dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or being overly formal, unless clearly defined in the various embodiments of the present application.

[0039] The following will describe in detail some embodiments of the present application with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0040] In the embodiments of the present application, the adjustable circuit can realize the functions of voltage regulation and current regulation simultaneously in the same circuit, and can be applied to the occasion of power device discharging to adjust the output current and output voltage of the power device, and improve the reliability and stability of the output voltage and current of the power device, etc. Among them, the above-mentioned power device can be a power module with a function of electrical energy output, such as a battery, a battery pack, etc., or a device including a power module and auxiliary circuits such as a voltage conversion circuit.

[0041] Please refer to Figure 1 , which is a schematic structural diagram of an adjustable circuit 100 provided by an embodiment of the present application. Exemplarily, the adjustable circuit 100 includes a voltage stabilizing module 110, a current limiting module 120, a step-down module 130, and a protection module 140; specifically, the voltage stabilizing module 110 is connected to the output power port of the power device to keep the output voltage stable and accurately adjust the magnitude of the first voltage of the power device; the voltage stabilizing module 110, the current limiting module 120, and the step-down module 130 are connected in sequence to adjust the output current and output voltage; the voltage stabilizing module 110 is connected to the protection module 140 to direct the current in the abnormal state to the ground.

[0042] In this embodiment, the input end of the voltage stabilizing module 110 is used to connect to the power device, the output end of the voltage stabilizing module 110 is connected to the first end of the current limiting module 120, the feedback end of the voltage stabilizing module 110 is connected to the first end of the protection module 140, and the voltage stabilizing module 110 is used to adjust the first voltage output by the power device and stably output the second voltage to the current limiting module 120; the second end of the current limiting module 120 is connected to the first end of the step-down module 130, and the second end of the step-down module 130 is connected to the second end of the protection module 140; the current limiting module 120 is used to adjust the current output by the power device; the step-down module 130 and the current limiting module 120 are also used to jointly adjust the second voltage to obtain a third voltage, and the third voltage is the target voltage output by the power device after being adjusted by the adjustable circuit 100; the protection module 140 is used to perform overcurrent and / or overvoltage protection on the adjustable circuit 100.

[0043] To better understand the adjustable circuit 100, each component in the adjustable circuit 100 will be described in detail below. Please refer to Figure 2 , which is a schematic circuit diagram of an adjustable circuit 100 provided by an embodiment of the present application.

[0044] In one embodiment, the voltage regulation module 110 includes a voltage regulation chip U1, a variable resistor R3, and a voltage dividing resistor R2; the voltage regulation module 110 is further configured to adjust the first voltage by adjusting the resistance value of the variable resistor R3 to obtain a second voltage; the input terminal IN of the voltage regulation chip U1 is connected to the output power supply port of the power supply device, the first end of the variable resistor R3 is grounded to GND, the second end of the variable resistor R3 is respectively connected to the common terminal ADJ of the voltage regulation chip U1, the first end of the voltage dividing resistor R2, and the first end of the protection module 140, and the second end of the voltage dividing resistor R2 is respectively connected to the output terminal OUT of the voltage regulation chip U1 and the first end of the current limiting module 120. The voltage regulation module 110 further includes an input capacitor C1; the first end of the input capacitor C1 is respectively connected to the output power supply port of the power supply device and the input terminal of the voltage regulation chip U1, and the second end of the input capacitor C1 is connected to the first end of the variable resistor R3, and the second end of the input capacitor C1 is grounded to GND.

[0045] In this embodiment, the input terminal of the voltage regulation chip U1 is the port for receiving the first voltage, and the first voltage will be regulated to a specified voltage. For example, the input terminal IN of the voltage regulation chip U1 can be used to feed in a first voltage of 12V, and the voltage regulation module 110 is configured to regulate the first voltage to a second voltage of 10V. The common terminal ADJ of the voltage regulation chip U1 is the port that allows controlling the voltage output, and the output terminal OUT of the voltage regulation chip U1 is the port for outputting regulated voltage. The voltage across the voltage dividing resistor R2 is the reference voltage, which is fixed and unchanged. In order to adjust the output, we change the resistance value of the variable resistor R3 to different resistances, so as to output an adjustable second voltage. When the output voltage of the voltage regulation chip U1 changes, the output capacitor C1 can discharge smoothly, avoiding the pressure difference caused by capacitor discharge, avoiding problems such as circuit flashing and jitter, and maintaining the operation stability of the voltage regulation chip U1.

[0046] Exemplarily, the second voltage output by the voltage regulation module 110 is determined by the following formula: In the formula, V3 is the second voltage, V0 is the reference voltage, R2 is the resistance value of the voltage dividing resistor R2, and R3 is the resistance value of the variable resistor R3, where the magnitude of the reference voltage is 1.25V. It can be seen from the above formula that the larger the resistance value of the variable resistor R3, the larger the second voltage. For example, in practical applications, it is necessary to regulate the first voltage of 12V input in the voltage regulation module 110 to a second voltage of 5V. According to the above formula, in order to make the voltage regulation module 110 output a second voltage of 5V, the resistance value of the voltage dividing resistor R2 is 240Ω. At this time, the resistance value of the variable resistor R3 is set to 720Ω.

[0047] It can be understood that in circuit design, by adjusting the first voltage of the voltage regulation module 110 and the resistance value of the variable resistor R3, different regulated output voltages can be achieved and the voltage regulation ability for different loads can be optimized. The voltage regulation module 110 has effective voltage regulation ability and can output a stable adjustable voltage. At the same time, the voltage regulation module 110 has a maximum output current. Since the maximum output current of the voltage regulation module 110 is not adjustable, the buck module 130 and the current limiting module 120 are required to regulate the maximum output current of the voltage regulation module 110.

[0048] In one embodiment, the current limiting module 120 includes a current limiting resistor R1; the first end of the current limiting resistor R1 is connected to the first output end of the voltage regulation module 110, and the second end of the current limiting resistor R1 is connected to the first end of the buck module 130. The buck module 130 includes a first diode D1 and a second diode D2; the anode of the first diode D1 is connected to the second end of the current limiting module 120, the cathode of the first diode D1 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the second end of the protection module 140.

[0049] Exemplarily, the first end of the current limiting resistor R1 is connected to the anode of the first diode D1, and the second end of the current limiting resistor R1 is connected to the second end of the voltage dividing resistor R2.

[0050] In this embodiment, the output current of the power supply device is regulated based on the voltage drops of the first diode D1, the second diode D2, and the third diode D3, and the resistance value of the current limiting resistor R1. The series circuit of the voltage dividing resistor R2 and the third diode D3 is connected in parallel with the series circuit of the first diode D1, the second diode D2, and the current limiting resistor R1, that is, the voltage across the series circuit of the voltage dividing resistor R2 and the third diode D3 is equal to the voltage across the series circuit of the first diode D1, the second diode D2, and the current limiting resistor R1. The first diode D1 and the second diode D2 are used to reduce the voltage across the current limiting resistor R1. The adjustable circuit 100 regulates the maximum output current of the voltage regulation module 110 by setting current limiting resistors R1 with different resistance values to achieve the function of adjustable output current. It can be understood that the voltage across the current limiting resistor R1 depends on the voltage drops of the first diode D1, the second diode D2, and the third diode D3. The voltage across the current limiting resistor R1 is equal to the sum of the reference voltage and the voltage drop of the third diode D3, minus the total voltage drop of the first diode D1 and the second diode D2.

[0051] Exemplarily, the output current of the power supply device can be calculated based on the reference voltage, the voltage drop of the third diode D3, the total voltage drop of the first diode D1 and the second diode D2, and the resistance value of the current limiting resistor R1.

[0052] For example, in one embodiment, the calculation formula for the current output by the power supply device is: In Equation (2), I is the current output by the power supply device, V1 is the voltage drop of the third diode D3, V0 is the voltage across the voltage-dividing resistor R2, that is, the reference voltage, V2 is the total voltage drop of the first diode D1 and the second diode D2, and R1 is the resistance value of the current-limiting resistor R1.

[0053] Exemplarily, the output target voltage of the power supply device can be calculated based on the reference voltage, the resistance value of the voltage-dividing resistor R2, the resistance value of the variable resistor R3, the voltage across the current-limiting resistor R1, and the total voltage drop of the first diode D1 and the second diode D2.

[0054] For example, in one embodiment, the calculation formula for the target voltage is: In Equation (1), V is the target voltage.

[0055] Optionally, the first diode, the second diode, and the third diode are selected to have the same or different voltage drops, and the voltage across the current-limiting resistor is close to zero. It can be understood that the first diode D1, the second diode D2, and the third diode D3 can be selected to have the same or different voltage drops according to actual needs. From the above calculation formula, the output target voltage of this power supply device is equal to the difference between the second voltage output by the voltage stabilization module 110, the total voltage drop of the first diode D1 and the second diode D2, and the voltage across the current-limiting resistor R1. The smaller the change in the output target voltage of the power supply device following the current change, the higher the target voltage accuracy. Therefore, during circuit design, select the voltage drops of the corresponding first diode, second diode, and third diode, and make the value of V0 + V1 - V2 in Equation (2) close to zero, that is, the voltage across the current-limiting resistor R1 is close to zero, so that the voltage across the current-limiting resistor R1 will be smaller and the change in the target voltage following the current will be smaller, thus meeting the requirement of improving the accuracy of the output target voltage.

[0056] In one embodiment, the protection module 140 includes a third diode D3; the cathode of the third diode D3 is connected to the cathode of the second diode D2, and the anode of the third diode D3 is connected to the second output terminal of the voltage stabilization module 110. Exemplarily, the anode of the third diode D3 is connected to the series node of the variable resistor R3 and the voltage-dividing resistor R2.

[0057] In this embodiment, when an overcurrent occurs in the adjustable circuit 100, the third diode D3 is used to perform reverse cut-off to reduce the current. When the current exceeds the rated extreme value of the diode, the third diode D3 will become conductive and direct the excess current to the ground, which can reduce the current passing through the adjustable circuit 100, thereby protecting the adjustable circuit 100. When an overvoltage occurs in the adjustable circuit 100, the third diode D3 is used to perform reverse conduction to reduce the voltage. When the voltage exceeds the rated extreme value of the third diode D3, the third diode D3 will become conductive and direct the excess voltage to the ground, thereby protecting other devices. The third diode D3 serves as a protection device for the adjustable circuit 100, and can reduce the damage to the adjustable circuit 100 by directing the excess current or voltage to the ground, thereby protecting the safety and stability of the entire adjustable circuit 100.

[0058] It can be understood that since the voltage stabilizing module 110 in the adjustable circuit 100 adjusts the output voltage, it has the maximum output current and cannot adjust the output current. In this application, by setting the current limiting resistor R1, the output current is adjusted, so that the adjustable circuit 100 can adjust the output current while adjusting the output target voltage of the power supply device. In this application, the third diode D3 is set to protect the adjustable circuit 100 against overvoltage or overcurrent. This application also sets the first diode D1 and the second diode D2 to reduce the voltage across the current limiting resistor R1. Since the output target voltage of the power supply device is equal to the difference between the second voltage and the total voltage drop of the first diode D1 and the second diode D2 and the voltage across the current limiting resistor R1, in practical applications, when the output current of the power supply device is fixed, the resistance of the current limiting resistor R1 can be reduced to nearly zero, so that the voltage across the current limiting resistor R1 can be ignored in the process of calculating the output voltage of the power supply device, thereby improving the accuracy of the output voltage of the power supply device.

[0059] This application also proposes a voltage regulator, which includes the adjustable circuit 100 in any of the above embodiments.

[0060] Specifically, the voltage regulator can be used in the power supplies of various devices and systems, including computers, communication devices, household appliances, etc. The voltage regulator can also be used to prevent the occurrence of ripple phenomena such as overvoltage and overcurrent, so that the circuit operates stably, improving the reliability and performance of the system. By applying the adjustable circuit 100 with voltage and current in the voltage regulator, the ability to adapt to load changes can be realized, so that the output voltage always remains stable. When abnormal situations such as excessive input voltage fluctuations or load short circuits occur, the adjustable circuit 100 in the voltage regulator can automatically control the output voltage and current to protect the circuit components in the voltage regulator from being damaged by overvoltage or overcurrent.

[0061] It should be understood that the adjustable circuit 100 of this embodiment may exist alone in the form of a packaged circuit module, or may be a part of the above voltage regulator, that is, disposed inside the voltage regulator, which is not limited here.

[0062] This application also provides a power supply device, including the voltage regulator of any of the above embodiments.

[0063] Specifically, the main function of the power supply device with a voltage regulator is to convert the voltage of the input power supply into a stable and reliable output voltage, and provide adjustment and protection functions, so as to ensure the normal and stable operation of electronic devices, industrial automation devices and other devices. The power supply device can be used in electronic devices, communication devices, industrial machinery and automation devices, etc. Different fields and different types of devices require a stable output voltage to ensure the normal operation, stable performance and lifespan of the devices. The power supply device with a voltage regulator, as a key component to ensure the normal operation of various devices, has a wide range of application fields.

[0064] The above are only the specific implementation manners of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application.

Claims

1. An adjustable circuit, characterized in that, Comprising: A voltage stabilizing module, a current limiting module, a step-down module, and a protection module; The input end of the voltage stabilizing module is used to connect to a power supply device, the output end of the voltage stabilizing module is connected to the first end of the current limiting module, the feedback end of the voltage stabilizing module is connected to the first end of the protection module, and the voltage stabilizing module is used to adjust the first voltage output by the power supply device and stably output a second voltage to the current limiting module; The second end of the current limiting module is connected to the first end of the step-down module, and the second end of the step-down module is connected to the second end of the protection module; The current limiting module is used to adjust the current output by the power supply device; The step-down module and the current limiting module are further used to jointly adjust the second voltage to obtain a third voltage, and the third voltage is the target voltage output by the power supply device after being adjusted by the adjustable circuit; The protection module is used to perform overcurrent and / or overvoltage protection on the adjustable circuit.

2. The adjustable circuit according to claim 1, wherein The current limiting module includes a current limiting resistor; The first end of the current limiting resistor is connected to the output end of the voltage stabilizing module, and the second end of the current limiting resistor is connected to the first end of the step-down module.

3. The adjustable circuit according to claim 2, wherein The step-down module includes a first diode and a second diode; The anode of the first diode is connected to the second end of the current limiting module, the cathode of the first diode is connected to the anode of the second diode, and the cathode of the second diode is connected to the second end of the protection module.

4. The adjustable circuit according to claim 3, characterized in that, The protection module includes a third diode; The cathode of the third diode is connected to the cathode of the second diode, and the anode of the third diode is connected to the feedback end of the voltage stabilizing module.

5. The adjustable circuit according to claim 4, characterized in that, The voltage stabilizing module includes a voltage stabilizing chip, a variable resistor, and a voltage dividing resistor; The voltage stabilizing module is further used to adjust the first voltage by adjusting the resistance value of the variable resistor to obtain the second voltage; The input end of the voltage stabilizing chip is connected to the output power supply port of the power supply device, the first end of the variable resistor is grounded, the second end of the variable resistor is respectively connected to the common end of the voltage stabilizing chip, the first end of the voltage dividing resistor, and the first end of the protection module, and the second end of the voltage dividing resistor is respectively connected to the output end of the voltage stabilizing chip and the first end of the current limiting module.

6. The adjustable circuit according to claim 5, wherein The calculation formula for the target voltage is: In Equation (1), V is the target voltage, V0 is the voltage across the voltage dividing resistor, R2 is the resistance value of the voltage dividing resistor, R3 is the resistance value of the variable resistor, I is the current output by the power supply device, V2 is the total voltage drop of the first diode and the second diode, and R1 is the resistance value of the current limiting resistor.

7. The adjustable circuit according to claim 6, wherein The calculation formula for the current output by the power supply device is: In Equation (2), V1 is the voltage drop of the third diode.

8. The adjustable circuit according to claim 4, wherein The first diode, the second diode, and the third diode are selected to have the same or different voltage drops.

9. A voltage regulator, characterized in that, Comprising the adjustable circuit according to any one of claims 1-8.

10. A power supply device, characterized in that, Comprising the voltage regulator according to claim 9.

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