A negative voltage circuit and electronic device

Abstract

This utility model discloses a negative voltage circuit and electronic device, applied in the field of buck circuit design. It includes: a buck adjustable circuit and a negative voltage multiplier circuit. The buck adjustable circuit includes a buck regulator, and the negative voltage multiplier circuit includes a switching regulator. The input pin of the buck regulator serves as the input terminal of the buck adjustable circuit and is connected to a voltage source. The output pin of the buck regulator serves as the output terminal of the buck adjustable circuit and is connected to the input pin of the switching regulator, which serves as the input terminal of the negative voltage multiplier circuit, to acquire the voltage signal corresponding to the voltage source and output the corresponding buck signal. The output pin of the switching regulator serves as the output terminal of the negative voltage multiplier circuit and is connected to a pluggable terminal block to output the negative voltage signal or the multiplier signal corresponding to the buck signal. Therefore, this application improves the buck efficiency, expands the voltage range, and enhances the load-carrying capacity of the negative voltage output by using a buck regulator and a switching regulator, while reducing the need for heat dissipation.

Description

Technical Field

[0001] This utility model relates to the field of step-down circuit design, and in particular to a negative voltage circuit and electronic equipment. Background Technology

[0002] The basic function of a voltage circuit is to convert an input positive voltage into a stable negative voltage output (e.g., +2V to -2V). This conversion is limited to the conversion of voltage values, not the conversion of direct current (DC) to alternating current (AC). This type of circuit is commonly used in scenarios requiring symmetrical positive and negative power supplies, such as operational amplifier-limited DC-DC converters (DC-DC converters are devices that convert electrical energy from one voltage value to another in a DC circuit), data converters (analog-to-digital converters and digital-to-analog converters), signal processing sections of communication equipment, and certain industrial control or testing equipment requiring reverse bias, to meet the negative voltage power supply requirements of specific devices.

[0003] Existing technologies such as Figure 1 As shown, a linear regulator negative voltage output circuit is used. The front stage consists of a charge pump U12 and surrounding circuitry (capacitors C11, C12, C13, C14; diodes D11 and D12). The rear stage consists of an LDO (Low Dropout Regulator) linear regulator chip U11 and surrounding circuitry (capacitors C15, C16, C17). In this circuit, the charge pump U12 uses its own switch and surrounding capacitors to boost / invert the voltage. The LDO linear regulator chip U11 then steps down the inverted voltage. In other words, Figure 1 The circuit shown first inverts the voltage before performing a step-down operation. However, the internal switches of the charge pump U12 and the components in the surrounding circuitry cause power losses, further reducing efficiency. Furthermore, the LDO linear regulator chip U11 becomes the main heat source during the step-down process due to the heat dissipation of its internal components, thus requiring a heat sink and increasing cost. Meanwhile, because the existing technology uses an inversion-then-step-down operation, and the current charge pump U12's own voltage withstand capability is limited to the range of 3.3V to 4.0V, its input voltage is limited.

[0004] Given the above-mentioned technologies, finding a high-efficiency negative voltage circuit is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this invention is to provide a negative voltage circuit and electronic device that can solve the problems of low efficiency, limited input voltage, and increased cost due to the need for heat dissipation design in existing linear regulated negative voltage output circuits.

[0006] To solve the above-mentioned technical problems, this utility model provides a negative voltage circuit, including: a step-down adjustable circuit and a negative voltage multiplier circuit, wherein the step-down adjustable circuit includes a step-down regulator and the negative voltage multiplier circuit includes a switching regulator.

[0007] The input pin of the buck regulator is connected to the voltage source as the input terminal of the buck adjustable circuit, and the output pin of the buck regulator is connected to the input pin of the switching regulator, which is the input terminal of the negative voltage multiplier circuit, to obtain the voltage signal corresponding to the voltage source and output the corresponding buck signal.

[0008] The output pin of the switching regulator is connected to a pluggable terminal block as the output terminal of the negative voltage multiplier circuit, and is used to output the negative voltage signal or the voltage multiplier signal corresponding to the step-down signal.

[0009] Preferably, the adjustable step-down circuit further includes: a Schottky diode, a first inductor, and an adjustable resistor;

[0010] The cathode of the Schottky diode is connected to the output pin of the buck regulator and the first terminal of the first inductor.

[0011] The second terminal of the first inductor is connected to the first fixed terminal of the adjustable resistor and the input terminal of the negative voltage multiplier circuit;

[0012] The anode of the Schottky diode is connected to the second fixed terminal of the adjustable resistor and grounded;

[0013] The moving end of the adjustable resistor is connected to the feedback pin of the buck regulator.

[0014] Preferably, the adjustable step-down circuit further includes: a transient suppression diode, a first capacitor, and a second capacitor;

[0015] Among them, the first terminal of the transient suppression diode is connected to the first terminal of the first capacitor, the first terminal of the second capacitor, the input pin of the buck regulator and the voltage source;

[0016] The second terminal of the transient suppression diode is connected to the second terminal of the first capacitor and the second terminal of the second capacitor, and is grounded.

[0017] Preferably, the adjustable step-down circuit further includes: a third capacitor and a current-limiting resistor;

[0018] The first terminal of the third capacitor is connected to the second terminal of the first inductor, the first fixed terminal of the adjustable resistor, and the input terminal of the negative voltage multiplier circuit.

[0019] The first terminal of the current-limiting resistor is connected to the second fixed terminal of the adjustable resistor;

[0020] The second terminal of the third capacitor is connected to the second terminal of the current-limiting resistor and grounded.

[0021] Preferably, the adjustable step-down circuit further includes: a second inductor and a fourth capacitor;

[0022] Among them, the first end of the second inductor is connected to the second end of the first inductor, the first fixed end of the adjustable resistor and the first end of the third capacitor;

[0023] The second terminal of the second inductor is connected to the first terminal of the fourth capacitor and the input terminal of the negative voltage multiplier circuit;

[0024] The second terminal of the fourth capacitor is grounded.

[0025] Preferably, the negative voltage multiplier circuit further includes: a fifth capacitor;

[0026] The first terminal of the fifth capacitor is connected to the positive pin of the switching regulator.

[0027] The second terminal of the fifth capacitor is connected to the negative pin of the switching regulator.

[0028] Preferably, the negative voltage multiplier circuit further includes: a sixth capacitor and a seventh capacitor;

[0029] Among them, the first terminal of the sixth capacitor is connected to the first terminal of the seventh capacitor and grounded;

[0030] The second terminal of the sixth capacitor is connected to the second terminal of the seventh capacitor, the input pin of the switching regulator, and the output terminal of the buck adjustable circuit.

[0031] Preferably, the negative voltage multiplier circuit further includes: an eighth capacitor;

[0032] The first terminal of the eighth capacitor is connected to the output pin of the switching regulator and the first terminal of the pluggable terminal block.

[0033] The second terminal of the eighth capacitor is connected to the second terminal of the pluggable terminal block and grounded.

[0034] Preferably, the negative voltage multiplier circuit further includes: a fuse;

[0035] The first end of the fuse is connected to the second end of the sixth capacitor, the second end of the seventh capacitor, and the input pin of the switching regulator.

[0036] The second terminal of the fuse is connected to the output terminal of the step-down adjustable circuit.

[0037] On the other hand, this application also provides an electronic device including the aforementioned negative voltage circuit.

[0038] Therefore, this application employs a buck regulator to first step down the voltage signal, and then a switching regulator to perform a negative / voltage multiplier operation on the stepped-down signal. Since the buck regulator has a voltage tolerance range of 1-100V and no internal switch, it expands the voltage range, increases the load-carrying capacity of the negative voltage output, and improves the buck conversion efficiency. Furthermore, this application eliminates the need for a low-dropout linear regulator for the buck operation, thus reducing the requirements for heat dissipation in the design. Simultaneously, the two-stage architecture constructed using an adjustable buck circuit and a negative voltage multiplier circuit separates the high-voltage processing and negative / voltage multiplier generation functions, avoiding signal interference. This makes it suitable for applications requiring high-voltage input to precise negative voltage conversion, such as operational amplifier power supplies, industrial sensors, and testing equipment. Attached Figure Description

[0039] To more clearly illustrate the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a circuit diagram of a linear regulated negative voltage output circuit in the prior art;

[0041] Figure 2 A structural diagram of a negative voltage circuit provided in an embodiment of this application;

[0042] Figure 3 A circuit diagram of the adjustable step-down circuit provided in the embodiments of this application;

[0043] Figure 4 The circuit diagram of the negative voltage multiplier circuit provided in the embodiments of this application. Detailed Implementation

[0044] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0045] The core of this invention is to provide a negative voltage circuit and an electronic device.

[0046] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Figure 2 A structural diagram of a negative voltage circuit provided in an embodiment of this application is shown below. Figure 2 As shown, it includes: a step-down adjustable circuit 1 and a negative voltage multiplier circuit 2, wherein the step-down adjustable circuit 1 includes a step-down regulator U1, and the negative voltage multiplier circuit 2 includes a switching regulator U2. In addition, Figure 2 It also includes: voltage source 3 and pluggable terminal block K.

[0048] The circuit connection is as follows: the input pin of the buck regulator U1 is connected to the voltage source 3 as the input terminal of the buck adjustable circuit 1; the output pin of the buck regulator U1 is connected to the input pin of the switching regulator U2, which is the input terminal of the negative voltage multiplier circuit 2; the output pin of the switching regulator U2 is connected to the pluggable terminal K as the output terminal of the negative voltage multiplier circuit 2.

[0049] In this embodiment, voltage source 3 is mainly used to provide a high-voltage signal and is input to buck adjustable circuit 1 through an input pin connected to buck regulator U1. Buck adjustable circuit 1 performs a voltage reduction operation on the voltage signal through buck regulator U1 and peripheral circuits. During the voltage reduction operation, the voltage reduction amplitude is adjustable. That is to say, the voltage reduction signal output by buck adjustable circuit 1 does not correspond to only one voltage value, but corresponds to multiple voltage values ​​according to the voltage reduction amplitude. Negative voltage multiplier circuit 2 obtains the voltage reduction signal through the input terminal connected to switching regulator U2 and buck regulator U1. It performs the opposite operation and multiplication operation on the voltage reduction signal through switching regulator U2 and peripheral circuits, thereby outputting the corresponding negative voltage signal or voltage multiplier signal.

[0050] For example, if the voltage signal corresponds to a voltage value of 24V, after passing through the adjustable step-down circuit 1, the voltage value of the output step-down signal is 2V (or 4V, etc., the specific step-down range can be adjusted); when the step-down signal with a voltage value of 2V passes through the negative voltage multiplier circuit 2, the voltage value of the output negative voltage signal is -2V, or the voltage value of the output doubled voltage signal is 4V.

[0051] As a preferred option, the buck regulator U1 can be model LM2576T-ADJ; the switching regulator U2 can be model MAX660MX. The buck regulator U1 (LM2576T-ADJ) can efficiently step down a wide-range high voltage (such as industrial 24V) of 4-40V to an intermediate voltage of around 2V, with a conversion efficiency of 85%. Then, the switching regulator U2 (MAX660MX) performs charge pump voltage inversion, overcoming the limitations of the conventional 1.5V-5.5V input range and significantly improving the load-carrying capacity of the negative voltage output, increasing it by 10 times to the 100mA level compared to a pure charge pump solution. Furthermore, both of these regulator models can control the system ripple to within 30mV when outputting a -2V negative voltage signal.

[0052] The present invention provides a negative voltage circuit comprising: a step-down adjustable circuit and a negative voltage multiplier circuit. The step-down adjustable circuit includes a step-down regulator, and the negative voltage multiplier circuit includes a switching regulator. The input pin of the step-down regulator serves as the input terminal of the step-down adjustable circuit and is connected to a voltage source. The output pin of the step-down regulator serves as the output terminal of the step-down adjustable circuit and is connected to the input pin of the switching regulator, which serves as the input terminal of the negative voltage multiplier circuit, to acquire the voltage signal corresponding to the voltage source and output the corresponding step-down signal. The output pin of the switching regulator serves as the output terminal of the negative voltage multiplier circuit and is connected to a pluggable terminal block to output the negative voltage signal or the multiplier signal corresponding to the step-down signal. Therefore, this application employs a buck regulator to first step down the voltage signal, and then a switching regulator to perform a negative / voltage multiplier operation on the stepped-down signal. Since the buck regulator has a voltage tolerance range of 1-100V and no internal switch, it expands the voltage range, increases the load-carrying capacity of the negative voltage output, and improves the buck conversion efficiency. Furthermore, this application eliminates the need for a low-dropout linear regulator for the buck operation, thus reducing the requirements for heat dissipation in the design. Simultaneously, the two-stage architecture constructed using an adjustable buck circuit and a negative voltage multiplier circuit separates the high-voltage processing and negative / voltage multiplier generation functions, avoiding signal interference. This makes it suitable for applications requiring high-voltage input to precise negative voltage conversion, such as operational amplifier power supplies, industrial sensors, and testing equipment.

[0053] Based on the above embodiments, as a preferred embodiment, such as... Figure 3 As shown, its adjustable step-down circuit 1 includes: a step-down regulator U1, a Schottky diode D1, a first inductor L1, an adjustable resistor R1, a transient suppression diode D1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a current-limiting resistor R2, a second inductor L2, and a fourth capacitor C4.

[0054] The circuit connections are as follows: the cathode of Schottky diode D1 is connected to the output pin (OUTPUT) of buck regulator U1 and the first terminal of the first inductor L1; the second terminal of the first inductor L1 is connected to the first fixed terminal of adjustable resistor R1, the first terminal of third capacitor C3, and the first terminal of second inductor L2; the first terminal of current-limiting resistor R2 is connected to the second fixed terminal of adjustable resistor R1; the first terminal of transient suppression diode D1 is connected to the first terminal of first capacitor C1, the first terminal of second capacitor C2, the input pin (VIN) of buck regulator U1, and voltage source 3 (i.e., Figure 3 The second terminal of the second inductor L2 is connected to the first terminal of the fourth capacitor C4 and the input terminal of the negative voltage multiplier circuit 2 (i.e., +24V); the second terminal of the second inductor L2 is connected to the first terminal of the fourth capacitor C4 and the input terminal of the negative voltage multiplier circuit 2 (i.e., +24V). Figure 3 The +2V terminal of the capacitor is connected to the ground; the second terminal of the transient suppression diode D2, the second terminal of the first capacitor C1, the second terminal of the second capacitor C2, the anode of the Schottky diode D1, the second terminal of the third capacitor C3, the second terminal of the current limiting resistor R2, and the second terminal of the fourth capacitor C4 are connected to the ground. At the same time, the two pins of the buck regulator U1 are also grounded.

[0055] In a specific embodiment, the core function of the adjustable buck circuit 1 is to convert the input voltage signal (e.g., 24V) into a stable buck signal (e.g., 2V). The 24V DC voltage passes through the transient suppression diode D1. When the internal switch of the buck regulator U1 is turned on, the first capacitor C1 discharges rapidly, providing a large instantaneous current to the first inductor L1 (avoiding voltage drops caused by direct power supply draw). The first inductor L1 is in the energy storage stage; when current flows through it, electrical energy is converted into magnetic energy for storage, suppressing current surges and smoothing the output waveform. When the internal switch of the buck regulator U1 is turned off, the first inductor L1 is in the energy release stage. The first inductor L1 freewheels through the Schottky diode D1, maintaining continuous load current, and the released magnetic energy is converted into electrical energy to supply the load. In other words, this application uses a combination of the Schottky diode D1 and the first inductor L1 to achieve efficient and stable voltage conversion.

[0056] In the above circuit, the main function of Schottky diode D1 is freewheeling protection. This is because the forward voltage drop of Schottky diode D1 (0.3~0.5V) is much lower than that of ordinary diodes, reducing energy loss and eliminating reverse recovery charge, thus avoiding switching losses. Furthermore, Schottky diode D1's fast conduction characteristic absorbs the back electromotive force generated when the inductor is turned off, protecting the internal switching transistor of the buck regulator U1 from high-voltage breakdown.

[0057] It should also be noted that the adjustable resistor R1 is used to adjust the voltage drop amplitude; the second capacitor C2 is used to absorb high-frequency noise, thereby suppressing the high-frequency noise generated by the operation of the internal switching transistor of the buck regulator U1; the current-limiting resistor R2 is used for current limiting; and the second inductor L2 and the fourth capacitor C4 are used for signal filtering.

[0058] It should also be noted that the embodiments provided in this application are only one possible implementation method, but are not limited to this only implementation method. Users can set their own implementation methods according to their needs.

[0059] This application provides a circuit design method for a step-down adjustable circuit. The circuit under this method improves the step-down efficiency, expands the voltage range, and enhances the load-carrying capacity of the negative voltage output. It is also highly flexible, simple to use, and requires fewer external circuits.

[0060] Based on the above embodiments, as a preferred embodiment, such as... Figure 4 As shown, the negative voltage multiplier circuit 2 includes: a switching regulator U2, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a fuse F1.

[0061] The circuit connections are as follows: the first terminal of the fifth capacitor C5 is connected to the positive pin (C1+) of the switching regulator U2; the second terminal of the fifth capacitor C5 is connected to the negative pin (C1-) of the switching regulator U2; the first terminal of the sixth capacitor C6 is connected to the first terminal of the seventh capacitor C7 and grounded to GND; the second terminal of the sixth capacitor C6 is connected to the second terminal of the seventh capacitor C7, the input pin (V+) of the switching regulator U2, and the first terminal of the fuse F1; the first terminal of the eighth capacitor C8 is connected to the output pin (OUT) of the switching regulator U1 and the first terminal of the pluggable terminal block K; the second terminal of the eighth capacitor C8 is connected to the second terminal of the pluggable terminal block K and grounded to GND; the second terminal of the fuse F1 is connected to the output terminal of the adjustable step-down circuit 1 (i.e., Figure 4 +2V in the middle).

[0062] Among them, the MAX660MX switching regulator U2 employs a completely different charge pump technology to achieve voltage conversion. Its working principle involves controlling the charging and discharging process of the external fifth capacitor C5 through the internal switching matrix of the switching regulator U2: In the first stage, the fifth capacitor C5 is charged to the voltage corresponding to the step-down signal (2V); in the second stage, the switching regulator U2 itself does not reverse the capacitor polarity, but instead reverses the voltage through a charge pump mechanism. That is, through the connection between the fifth capacitor C5 and the negative pin (C1-) and positive pin (C1+) of the switching regulator U2, the fifth capacitor C5 is reversed, transferring the stored charge to the output terminal, thereby achieving voltage inversion or voltage multiplication. This switched-capacitor conversion method is simple and efficient; the switching regulator U2 only requires a few capacitors to operate, greatly simplifying circuit design.

[0063] Therefore, the negative voltage circuit provided in this application has the following advantages:

[0064] 1. In the cascaded architecture consisting of an LM2576T-ADJ step-down regulator and a MAX660MX switching regulator, the LM2576T-ADJ step-down regulator is responsible for stepping down the input voltage, reducing the higher input voltage (e.g., 24V) to an intermediate voltage (e.g., 2V). The MAX660MX switching regulator is used for voltage inversion or voltage multiplication, converting the output voltage of the adjustable step-down circuit to a negative voltage or a higher voltage. This design creatively utilizes the adjustable step-down circuit to handle 90% of the power, while the negative voltage multiplier circuit only performs polarity reversal. This allows the system to maintain the small size advantage of the negative voltage multiplier circuit while breaking through the traditional input voltage ≤6V limitation of circuits.

[0065] 2. A composite ripple suppression mechanism is adopted, namely, a three-stage filtering structure of "inductor-capacitor-capacitor" is developed. Its adjustable step-down circuit adopts π-type LC filtering, the subsequent negative voltage multiplier circuit is equipped with a fifth capacitor, and an eighth capacitor with a resistance value of <0.1Ω is added to the final output terminal. This structure reduces the ripple in the 1MHz frequency band to 18μVrms, which meets the instrumentation grade standard.

[0066] 3. Dynamic energy distribution technology, which adopts a front-end dynamic impedance matching design, uses the peripheral circuit of the LM2576T-ADJ buck regulator to adjust the intermediate voltage (which can also be understood as the voltage corresponding to the buck signal) in real time, so that the MAX660MX switching regulator always works at the optimal efficiency point (e.g., 88%).

[0067] On the other hand, this application also provides an electronic device including the aforementioned negative voltage circuit.

[0068] Since the embodiments of the electronic devices provided in this application are the same as the embodiments of the negative pressure circuit described above, this application will not repeat them here.

[0069] The foregoing has provided a detailed description of the negative voltage circuit and electronic device provided by this utility model. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

[0070] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. A negative voltage circuit, characterized in that, include: A step-down adjustable circuit and a negative voltage multiplier circuit, wherein the step-down adjustable circuit includes a step-down regulator and the negative voltage multiplier circuit includes a switching regulator; The input pin of the buck regulator is connected to the voltage source as the input terminal of the adjustable buck circuit, and the output pin of the buck regulator is connected to the input pin of the switching regulator, which is the input terminal of the negative voltage multiplier circuit, as the output terminal of the adjustable buck circuit. This is used to obtain the voltage signal corresponding to the voltage source and output the corresponding buck signal. The output pin of the switching regulator is connected to a pluggable terminal block as the output terminal of the negative voltage multiplier circuit, and is used to output the negative voltage signal or the voltage multiplier signal corresponding to the step-down signal.

2. The negative voltage circuit according to claim 1, characterized in that, The adjustable step-down circuit further includes: a Schottky diode, a first inductor, and an adjustable resistor; The cathode of the Schottky diode is connected to the output pin of the buck regulator and the first terminal of the first inductor. The second end of the first inductor is connected to the first fixed end of the adjustable resistor and the input end of the negative voltage multiplier circuit; The anode of the Schottky diode is connected to the second fixed terminal of the adjustable resistor and grounded; The movable end of the adjustable resistor is connected to the feedback pin of the buck regulator.

3. The negative voltage circuit according to claim 2, characterized in that, The adjustable step-down circuit further includes: a transient suppression diode, a first capacitor, and a second capacitor; The first terminal of the transient suppression diode is connected to the first terminal of the first capacitor, the first terminal of the second capacitor, the input pin of the buck regulator, and the voltage source. The second terminal of the transient suppression diode is connected to the second terminal of the first capacitor and the second terminal of the second capacitor, and is grounded.

4. The negative voltage circuit according to claim 3, characterized in that, The adjustable step-down circuit also includes: a third capacitor and a current-limiting resistor; The first terminal of the third capacitor is connected to the second terminal of the first inductor, the first fixed terminal of the adjustable resistor, and the input terminal of the negative voltage multiplier circuit. The first end of the current-limiting resistor is connected to the second fixed end of the adjustable resistor; The second terminal of the third capacitor is connected to the second terminal of the current-limiting resistor and grounded.

5. The negative voltage circuit according to claim 4, characterized in that, The adjustable step-down circuit further includes: a second inductor and a fourth capacitor; Wherein, the first end of the second inductor is connected to the second end of the first inductor, the first fixed end of the adjustable resistor and the first end of the third capacitor; The second terminal of the second inductor is connected to the first terminal of the fourth capacitor and the input terminal of the negative voltage multiplier circuit; The second terminal of the fourth capacitor is grounded.

6. The negative voltage circuit according to any one of claims 1-5, characterized in that, The negative voltage multiplier circuit also includes: a fifth capacitor; The first terminal of the fifth capacitor is connected to the positive pin of the switching regulator; The second terminal of the fifth capacitor is connected to the negative pin of the switching regulator.

7. The negative voltage circuit according to claim 6, characterized in that, The negative voltage multiplier circuit also includes: a sixth capacitor and a seventh capacitor; The first terminal of the sixth capacitor is connected to the first terminal of the seventh capacitor and grounded. The second terminal of the sixth capacitor is connected to the second terminal of the seventh capacitor, the input pin of the switching regulator, and the output terminal of the buck adjustable circuit.

8. The negative voltage circuit according to claim 7, characterized in that, The negative voltage multiplier circuit also includes: an eighth capacitor; The first end of the eighth capacitor is connected to the output pin of the switching regulator and the first end of the pluggable terminal block; The second terminal of the eighth capacitor is connected to the second terminal of the pluggable terminal block and grounded.

9. The negative voltage circuit according to claim 8, characterized in that, The negative voltage multiplier circuit also includes: a fuse; The first end of the fuse is connected to the second end of the sixth capacitor, the second end of the seventh capacitor, and the input pin of the switching regulator. The second end of the fuse is connected to the output end of the step-down adjustable circuit.

10. An electronic device, characterized in that, Includes the negative voltage circuit as described in any one of claims 1-9.

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