DC power supply surge protection circuit and device

Abstract

This application proposes a DC power surge protection circuit and device for use in the field of circuit technology. The DC power surge protection circuit is disposed between a DC power input interface and a subsequent circuit. The DC power surge protection circuit includes an inductor, a voltage differential trigger unit, and a switch unit. The first end of the inductor is connected to the DC power input interface, and the second end of the inductor is connected to the subsequent circuit via the switch unit. The first end of the switch unit is connected to the second end of the inductor, the second end of the switch unit is connected to the subsequent circuit, and the third end of the switch unit is connected to the third end of the voltage differential trigger unit. The first end of the voltage differential trigger unit is connected to the DC power input interface, and the second end of the voltage differential trigger unit is connected to the first end of the switch unit. This application aims to achieve high-power DCIN negative voltage surge protection at a low cost.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a DC power supply surge protection circuit and device. Background Art

[0002] In a DC power supply system, a negative voltage surge can cause a sudden drop in the DCIN (Direct Current Input) voltage, which in turn can cause problems such as shutdown / restart in downstream connected products.

[0003] Traditional negative voltage surge protection methods fall into two categories: connecting a diode in series with the DCIN circuit and adding a surge protection chip to the DCIN circuit. However, in practice, connecting a diode in series results in significant power loss, especially in high-power applications. Adding a surge protection chip is expensive and difficult to implement.

[0004] In summary, how to achieve high-power DCIN negative voltage surge protection at a lower cost has become a technical problem that needs to be urgently solved in this field. Summary of the Invention

[0005] This application proposes a DC power supply surge protection circuit, which aims to achieve high-power DCIN negative voltage surge protection at a lower cost.

[0006] To achieve the above objectives, the present application proposes a DC power surge protection circuit, which is arranged between a DC power input interface and a subsequent circuit. The DC power surge protection circuit includes an inductor, a voltage difference trigger unit, and a switch unit;

[0007] The first end of the inductor is connected to the DC power input interface, and the second end of the inductor is connected to the subsequent circuit through the switch unit;

[0008] The first end of the switch unit is connected to the second end of the inductor, the second end of the switch unit is connected to the subsequent circuit, and the third end of the switch unit is connected to the third end of the voltage difference trigger unit;

[0009] The first end of the pressure difference trigger unit is connected to the DC power input interface, and the second end of the pressure difference trigger unit is connected to the first end of the switch unit.

[0010] In one embodiment, the voltage difference trigger unit includes a first resistor and a transistor, the first end of the voltage difference trigger unit is the first end of the first resistor, the second end of the voltage difference trigger unit is the emitter of the transistor, and the third end of the voltage difference trigger unit is the collector of the transistor;

[0011] The second end of the first resistor is connected to the base of the transistor.

[0012] In one embodiment, the switch unit includes a PMOS transistor (positive metal-oxide-semiconductor field-effect transistor) and a voltage divider circuit, a first end of the switch unit is a drain of the PMOS transistor, a second end of the switch unit is a source of the PMOS transistor, and a third end of the switch unit is a gate of the PMOS transistor;

[0013] A first end of the voltage divider circuit is connected to the source of the PMOS tube, a second end of the voltage divider circuit is connected to the gate of the PMOS tube, and a third end of the voltage divider circuit is grounded.

[0014] In one embodiment, the voltage divider circuit includes a second resistor and a third resistor, the first end of the voltage divider circuit is the first end of the second resistor, the second end of the second resistor is connected to the first end of the third resistor, the second end of the voltage divider circuit is the voltage dividing point between the second resistor and the third resistor, and the third end of the voltage divider circuit is the second end of the third resistor.

[0015] In one embodiment, the DC power surge protection circuit further includes a first capacitor;

[0016] A first end of the first capacitor is connected to the DC power input interface, and a second end of the first capacitor is grounded.

[0017] In one embodiment, the DC power surge protection circuit further includes a second capacitor;

[0018] A first end of the second capacitor is connected to the first end of the switch unit, and a second end of the second capacitor is grounded.

[0019] In one embodiment, the inductance of the inductor is lower than a first preset threshold, the volume of the inductor is smaller than a second preset threshold, and the cost of the inductor is lower than a third preset threshold.

[0020] In one embodiment, the inductor is used to generate a voltage difference when a surge occurs, so as to trigger the voltage difference trigger unit to turn on.

[0021] In one embodiment, when the voltage difference trigger unit is turned on, it triggers the switch unit to be turned off, so as to cut off the power supply path between the DC power input interface and the subsequent circuit.

[0022] In addition, to achieve the above-mentioned purpose, the present application provides a DC power supply surge protection device, which includes a DC power supply surge protection circuit as described in any one of the above-mentioned items.

[0023] The DC power surge protection circuit proposed in this application is arranged between the DC power input interface and the subsequent circuit, and the DC power surge protection circuit includes an inductor, a voltage difference trigger unit and a switch unit; the first end of the inductor is connected to the DC power input interface, and the second end of the inductor is connected to the subsequent circuit through the switch unit; the first end of the switch unit is connected to the second end of the inductor, the second end of the switch unit is connected to the subsequent circuit, and the third end of the switch unit is connected to the third end of the voltage difference trigger unit; the first end of the pressure difference trigger unit is connected to the DC power input interface, and the second end of the pressure difference trigger unit is connected to the first end of the switch unit.

[0024] The DC power surge protection circuit proposed in this application utilizes an inductor, a voltage differential trigger unit, and a switch unit to work in concert. When faced with a DCIN voltage drop caused by a negative voltage surge, the inductor can prevent current mutations. Thus, when the DCIN positive voltage drops, the voltage after the inductor remains at a normal voltage. At this point, a significant voltage differential is instantly generated across the inductor, triggering the voltage differential trigger unit to conduct, which in turn triggers the switch unit to shut down. This leaves the subsequent circuits connected to the switch unit unaffected, preventing the subsequent connected products from shutting down or restarting due to voltage drop. This effectively suppresses surge voltages while reducing costs compared to using surge protection chips, achieving high-power DCIN negative voltage surge protection at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a circuit connection diagram of an embodiment of a DC power supply surge protection circuit of the present application;

[0028] Figure 2 This is another circuit diagram of an embodiment of the DC power surge protection circuit of the present application.

[0029] Figures 1 to 2 Description of Figure Numbers:

[0030]

[0031] The purpose, features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] It should be understood that the specific embodiments described herein are merely used to explain the technical solutions of the present application and are not intended to limit the present application.

[0033] In a DC power supply system, a negative voltage surge can cause a sudden drop in the DCIN voltage, which in turn can cause problems such as shutdown / restart in downstream connected products.

[0034] Traditional negative voltage surge protection methods include two types: connecting a diode in series with the DCIN circuit and adding a surge protection chip to the DCIN circuit. However, in actual applications, the series diode method will cause significant power loss and is not suitable for high-power scenarios. The method of adding a surge protection chip is expensive and difficult to promote.

[0035] In summary, how to achieve high-power DCIN negative voltage surge protection at a lower cost has become a technical problem that needs to be urgently solved in this field.

[0036] An embodiment of the present application provides a solution, proposing a DC power surge protection circuit, which is arranged between the DC power input interface DCIN+ and the subsequent circuit VCCIN. The DC power surge protection circuit includes an inductor L1, a voltage difference trigger unit 10 and a switch unit 20; the first end of the inductor L1 is connected to the DC power input interface DCIN+, and the second end of the inductor L1 is connected to the subsequent circuit VCCIN through the switch unit 20; the first end of the switch unit 20 is connected to the second end of the inductor L1, the second end of the switch unit 20 is connected to the subsequent circuit VCCIN, and the third end of the switch unit 20 is connected to the third end of the voltage difference trigger unit 10; the first end of the voltage difference trigger unit 10 is connected to the DC power input interface DCIN+, and the second end of the voltage difference trigger unit 10 is connected to the first end of the switch unit 20.

[0037] In summary, the DC power surge protection circuit proposed in the embodiment of the present application, through the coordinated work of the inductor L1, the voltage difference trigger unit 10, and the switch unit 20, can prevent the current from suddenly changing when facing the DCIN voltage drop problem caused by a negative voltage surge. Therefore, when the DCIN positive voltage drops suddenly, the voltage after the inductor L1 still maintains a normal voltage. At this time, a significant voltage difference is instantly generated across the inductor L1, triggering the voltage difference trigger unit 10 to turn on, and then triggering the switch unit 20 to turn off, so that the downstream circuit VCCIN connected to the switch unit 20 is not affected, avoiding the shutdown or restart phenomenon of the downstream connected products due to voltage drop. Thus, efficient suppression of surge voltage is achieved, and at the same time, compared with the use of surge protection chips, the cost is reduced, and the effect of achieving high-power DCIN negative voltage surge protection at a lower cost is achieved.

[0038] The following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings. If there are descriptions of "first" or "second" in the embodiments of this application, the descriptions of "first" or "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly specifying the number of the indicated technical features. Therefore, the features specified as "first" or "second" may explicitly or implicitly include at least one of such features.

[0039] This embodiment provides a DC power supply surge protection circuit, aiming to achieve high-power DCIN negative voltage surge protection at a relatively low cost.

[0040] Please refer to Figure 1 , Figure 1 This is a circuit diagram of the first embodiment of the DC power surge protection circuit of the present application.

[0041] In this embodiment, the DC power surge protection circuit is provided between the DC power input interface DCIN+ and the subsequent circuit VCCIN. The DC power surge protection circuit includes an inductor L1, a voltage difference trigger unit 10, and a switch unit 20.

[0042] The first end of the inductor L1 is connected to the DC power input interface DCIN+, and the second end of the inductor L1 is connected to the subsequent circuit VCCIN through the switch unit 20;

[0043] In this embodiment, a first end of the inductor L1 is connected to the DC power input interface DCIN+, and a second end of the inductor L1 is connected to the subsequent circuit VCCIN through the switch unit 20 to form a current transmission channel.

[0044] The first end of the switch unit 20 is connected to the second end of the inductor L1, the second end of the switch unit 20 is connected to the subsequent circuit VCCIN, and the third end of the switch unit 20 is connected to the third end of the voltage difference trigger unit 10;

[0045] In this embodiment, the first end of the switch unit 20 is connected to the second end of the inductor L1 to receive the current signal from the inductor L1. The second end of the switch unit 20 is connected to the subsequent circuit VCCIN to transmit the current to the load of the subsequent circuit. The third end of the switch unit 20 is connected to the third end of the voltage difference trigger unit 10 to form an interactive path for the control signal, ensuring that it can respond quickly and cut off the circuit under specific conditions.

[0046] It is worth mentioning that under normal circumstances, the switch unit 20 remains in the on state to ensure that the current is smoothly transmitted to the subsequent circuit VCCIN. When a voltage drop problem caused by a negative voltage surge occurs, the switch unit 20 quickly cuts off the circuit to protect the subsequent circuit VCCIN from damage.

[0047] A first end of the voltage difference trigger unit 10 is connected to the DC power input interface DCIN+, and a second end of the voltage difference trigger unit 10 is connected to a first end of the switch unit 20 .

[0048] In this embodiment, the voltage difference trigger unit 10 is responsible for monitoring the voltage changes across the inductor L1. Its first end is connected to the DC power input interface DCIN+ to sense the fluctuation of the input voltage in real time. Its second end is connected to the first end of the switch unit 20. By comparing the difference between the input voltage and the voltage at the switch unit 20, it is determined whether a protection action needs to be triggered. When an abnormal voltage difference is detected, the voltage difference trigger unit 10 will quickly send a control signal to the switch unit 20, prompting it to cut off the circuit, thereby protecting the subsequent circuit VCCIN from damage by surge voltage.

[0049] In a possible embodiment, Figure 2 As shown, the voltage difference trigger unit 10 includes a first resistor R1 and a transistor Q1, the first end of the voltage difference trigger unit 10 is the first end of the first resistor R1, the second end of the voltage difference trigger unit 10 is the emitter of the transistor Q1, and the third end of the voltage difference trigger unit 10 is the collector of the transistor Q1;

[0050] The second end of the first resistor R1 is connected to the base of the transistor Q1 .

[0051] In this embodiment, the voltage difference trigger unit 10 includes a first resistor R1 and a transistor Q1. It should be noted that the transistor Q1 in this embodiment is specifically a PNP transistor. On this basis, the first end of the first resistor R1 is connected to the DC power input interface DCIN+; the second end of the first resistor R1 is connected to the base of the transistor Q1 (i.e. Figure 2 B) connection; the emitter of transistor Q1 (i.e. Figure 2 E in the figure) is connected to the first end of the switch unit 20; the collector of the transistor (ie Figure 2C) is connected to the third terminal of the switching power supply.

[0052] Among them, the first resistor R1 plays the role of voltage division and current limiting in the voltage difference trigger unit 10. It is connected between the positive electrode of DCIN and the base of the transistor Q1. Through the voltage division effect, part of the input voltage is introduced into the base of the transistor Q1, thereby controlling the conduction state of the transistor Q1. At the same time, the first resistor R1 also limits the current flowing into the base of the transistor Q1 to prevent the transistor Q1 from being damaged due to excessive current.

[0053] The first resistor R1 and the transistor Q1 together constitute the voltage difference trigger unit 10. By monitoring the voltage difference between DCIN and the first end of the switch unit 20 in real time, that is, the voltage difference across the inductor L1, and controlling the conduction state of the transistor Q1 according to the change in the voltage difference, a corresponding control signal is sent to the switch unit 20 to achieve effective protection of the subsequent circuit VCCIN.

[0054] In a feasible embodiment, the switch unit 20 includes a PMOS transistor Q2 and a voltage divider circuit. The first end of the switch unit 20 is the drain of the PMOS transistor Q2, the second end of the switch unit 20 is the source of the PMOS transistor Q2, and the third end of the switch unit 20 is the gate of the PMOS transistor Q2.

[0055] The first end of the voltage divider circuit is connected to the source of the PMOS tube Q2 (i.e. Figure 2 The second end of the voltage divider circuit is connected to the gate of the PMOS tube Q2 (i.e. Figure 2 The third terminal of the voltage divider circuit is grounded.

[0056] In this embodiment, the switch unit 20 includes a PMOS tube Q2 and a voltage divider circuit. On this basis, the drain of the PMOS tube Q2 (ie Figure 2 D) is connected to the second end of the inductor L1, the source of the PMOS tube Q2 is connected to the subsequent circuit VCCIN, and the gate of the PMOS tube Q2 is connected to the collector of the transistor Q1.

[0057] The PMOS transistor Q2 controls the conduction state between the drain and source according to the change in the gate voltage. When the gate voltage is lower than a certain threshold of the source voltage, the PMOS transistor Q2 is turned on, allowing current to flow from the drain to the source, thereby connecting the subsequent circuit VCCIN. Conversely, when the gate voltage is higher than the source voltage or the gate voltage is insufficient to turn on the PMOS transistor Q2, the PMOS transistor Q2 is turned off, cutting off the path between the drain and the source, thereby disconnecting the subsequent circuit VCCIN. This on-off state change is controlled by a control signal sent by the voltage difference trigger unit 10.

[0058] The voltage divider circuit is used to generate a safe and sufficient voltage difference between the GS (gate and source) of the PMOS tube Q2 to ensure that the PMOS tube Q2 can turn on itself, and can also limit and adjust the voltage difference between the GS of the PMOS tube Q2 to not exceed the maximum allowable value.

[0059] The PMOS transistor Q2 and the voltage divider circuit together constitute the switch unit 20, which accurately controls the conduction state of the PMOS transistor Q2 by receiving the control signal sent by the voltage difference trigger unit 10, thereby achieving effective control and protection of the subsequent circuit VCCIN.

[0060] In a feasible embodiment, the voltage divider circuit includes a second resistor R2 and a third resistor R3, the first end of the voltage divider circuit is the first end of the second resistor R2, the second end of the second resistor R2 is connected to the first end of the third resistor R3, the second end of the voltage divider circuit is the voltage dividing point VG1 between the second resistor R2 and the third resistor R3, and the third end of the voltage divider circuit is the second end of the third resistor R3.

[0061] In this embodiment, the voltage divider circuit includes a second resistor R2 and a third resistor R3. On this basis, a first end of the second resistor R2 is connected to the source of the PMOS transistor Q2, a second end of the second resistor R2 is connected to the first end of the third resistor R3, a second end of the third resistor R3 is grounded, and a voltage dividing point VG1 between the second end of the second resistor R2 and the first end of the third resistor R3 is connected to the gate of the PMOS transistor Q2.

[0062] The resistance values ​​of the second resistor R2 and the third resistor R3 directly affect the voltage level of the voltage dividing point VG1. By adjusting the resistance values ​​of the second resistor R2 and / or the third resistor R3, the proportional relationship between the voltage at the voltage dividing point VG1 and the source voltage can be changed, thereby providing a stable divided voltage for the gate of the PMOS transistor Q2, ensuring that the PMOS transistor Q2 can operate accurately and reliably, and achieving effective protection for the subsequent circuit VCCIN.

[0063] In a feasible embodiment, the DC power surge protection circuit further includes a first capacitor C1;

[0064] A first end of the first capacitor C1 is connected to the DC power input interface DCIN+, and a second end of the first capacitor C1 is grounded.

[0065] In this embodiment, the first capacitor C1 is connected between the DC power input interface DCIN+ and ground to filter and stabilize the voltage. It can absorb transient voltage fluctuations and high-frequency noise at the power input end, reducing the impact of these interferences on the subsequent circuit VCCIN. At the same time, the first capacitor C1 can also provide short-term energy storage at the power input end to cope with sudden current demands and ensure stable operation of the circuit.

[0066] In a feasible embodiment, the DC power surge protection circuit further includes a second capacitor C2;

[0067] A first end of the second capacitor C2 is connected to the first end of the switch unit 20 , and a second end of the second capacitor C2 is grounded.

[0068] In this embodiment, the second capacitor C2 is connected between the first terminal of the switch unit 20 (i.e., the drain of the PMOS transistor Q2) and ground, providing filtering and energy storage. The second capacitor C2 absorbs voltage fluctuations and noise at the input of the switch unit 20, ensuring smooth operation of the PMOS transistor Q2 during its on and off phases. Furthermore, the second capacitor C2 provides additional current support when the switch unit 20 switches between connection and disconnection, reducing voltage drops and spikes and protecting the downstream circuit VCCIN from voltage surges.

[0069] The addition of first capacitor C1 and second capacitor C2 further enhances the performance and stability of the DC power surge protection circuit. By filtering, storing energy, and stabilizing voltage, they effectively reduce interference and fluctuations at the power input and the input of switch unit 20, ensuring reliable circuit operation under various operating conditions and providing a more stable and secure power supply environment for the subsequent circuit VCCIN.

[0070] In a feasible embodiment, the inductance value of the inductor L1 is lower than a first preset threshold, the volume of the inductor is smaller than a second preset threshold, and the cost of the inductor is smaller than a third preset threshold.

[0071] In this embodiment, the inductor L1 is an inductor having an inductance value lower than a first preset threshold, a volume smaller than a second preset threshold, and a cost less than a third preset threshold. The values ​​of the first preset threshold, the second preset threshold, and the third preset threshold can be set based on actual application scenarios and are not specifically limited in this embodiment.

[0072] In high-power scenarios, devices often experience large transient currents, and inductor L1 will hinder current changes. If the inductance value is too large, DCIN will not be able to supply sufficient transient current to the downstream circuit VCCIN, affecting normal operation of the device. In this embodiment, because the DCIN surge voltage changes rapidly, the inductor L1 with a very small inductance value can generate a sufficient voltage drop across the PNP transistor Q1 to turn on. The small inductor L1 has weak current suppression capability and has almost no effect when the downstream stage requires large transient current. Moreover, for the same flow rate, the small inductor L1 has the advantages of small size, low impedance, and low cost.

[0073] In a feasible embodiment, the inductor L1 is used to generate a voltage difference when a surge occurs, so as to trigger the voltage difference triggering unit 10 to turn on.

[0074] In this embodiment, when a surge voltage occurs, a voltage difference will be generated across the inductor L1 due to its own characteristics. The magnitude of the pressure difference depends on the amplitude of the surge voltage and the inductance value of the inductor L1. By reasonably setting the inductance value, it can be ensured that the pressure difference generated when a surge occurs is sufficient to trigger the pressure difference trigger unit 10 to turn on.

[0075] In a feasible embodiment, when the voltage difference trigger unit 10 is turned on, the trigger switch unit 20 is turned off to cut off the power supply path between the DC power input interface DCIN+ and the subsequent circuit VCCIN.

[0076] In this embodiment, after receiving the voltage difference signal generated by the inductor L1, the voltage difference trigger unit 10 will be quickly turned on, that is, the emitter and collector of the transistor Q1 are turned on. When the voltage difference trigger unit 10 is turned on, there is no voltage difference between the gate and source of the PMOS tube Q2, and the switch unit 20 will be quickly turned off, cutting off the power supply path between the DC power input interface DCIN+ and the subsequent circuit VCCIN, thereby effectively isolating the impact of the surge voltage on the subsequent circuit VCCIN and preventing the subsequent circuit VCCIN from being damaged by the surge voltage.

[0077] In summary, in this embodiment, the various links, such as the setting of the inductor L1's inductance value, the voltage difference generated when a surge occurs, the conduction of the voltage difference trigger unit 10, and the shutdown of the switch unit 20, together constitute the core protection mechanism of the DC power supply surge protection circuit. The coordinated operation of these units ensures that the circuit can respond quickly and effectively when facing a surge voltage, protecting the downstream circuit VCCIN from damage.

[0078] In addition, this embodiment further provides a DC power supply surge protection device, which includes any one of the DC power supply surge protection circuits described above.

[0079] The above are merely optional embodiments of the present application and do not limit the patent scope of the present application. All equivalent structural transformations made using the contents of the present application specification and drawings under the application concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A DC power supply negative voltage surge protection circuit, characterized in that: The DC power supply negative voltage surge protection circuit is arranged between the DC power supply input interface and the subsequent circuit, and the DC power supply negative voltage surge protection circuit includes an inductor, a pressure difference trigger unit and a switch unit; The first end of the inductor is connected to the DC power input interface, and the second end of the inductor is connected to the subsequent circuit through the switch unit; The first end of the switch unit is connected to the second end of the inductor, the second end of the switch unit is connected to the subsequent circuit, and the third end of the switch unit is connected to the third end of the voltage difference trigger unit; The first end of the pressure difference trigger unit is connected to the DC power input interface, and the second end of the pressure difference trigger unit is connected to the first end of the switch unit; The voltage difference trigger unit includes a first resistor and a transistor, the first end of the voltage difference trigger unit is the first end of the first resistor, the second end of the voltage difference trigger unit is the emitter of the transistor, and the third end of the voltage difference trigger unit is the collector of the transistor; The second end of the first resistor is connected to the base of the transistor; The switch unit includes a PMOS tube and a voltage divider circuit, the first end of the switch unit is the drain of the PMOS tube, the second end of the switch unit is the source of the PMOS tube, and the third end of the switch unit is the gate of the PMOS tube; A first end of the voltage divider circuit is connected to the source of the PMOS tube, a second end of the voltage divider circuit is connected to the gate of the PMOS tube, and a third end of the voltage divider circuit is grounded.

2. The DC power supply negative voltage surge protection circuit according to claim 1, wherein: The voltage divider circuit includes a second resistor and a third resistor, the first end of the voltage divider circuit is the first end of the second resistor, the second end of the second resistor is connected to the first end of the third resistor, the second end of the voltage divider circuit is the voltage dividing point between the second resistor and the third resistor, and the third end of the voltage divider circuit is the second end of the third resistor.

3. The DC power supply negative voltage surge protection circuit according to claim 1, wherein: The DC power supply negative voltage surge protection circuit further includes a first capacitor; A first end of the first capacitor is connected to the DC power input interface, and a second end of the first capacitor is grounded.

4. The DC power supply negative voltage surge protection circuit according to claim 1, wherein: The DC power supply negative voltage surge protection circuit further includes a second capacitor; A first end of the second capacitor is connected to the first end of the switch unit, and a second end of the second capacitor is grounded.

5. The DC power supply negative voltage surge protection circuit according to claim 1, wherein: The inductance value of the inductor is lower than a first preset threshold value, the volume of the inductor is smaller than a second preset threshold value, and the cost of the inductor is lower than a third preset threshold value.

6. The DC power supply negative voltage surge protection circuit according to claim 1, wherein: The inductor is used to generate a voltage difference when a surge occurs, so as to trigger the voltage difference trigger unit to turn on.

7. The DC power supply negative voltage surge protection circuit according to claim 6, characterized in that: When the voltage difference trigger unit is turned on, the switch unit is triggered to turn off, so as to cut off the power supply path between the DC power input interface and the subsequent circuit.

8. A DC power supply negative voltage surge protection device, characterized in that: The DC power supply negative voltage surge protection device includes a DC power supply negative voltage surge protection circuit according to any one of claims 1 to 7.

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