Lightning surge protection circuit and circuit board

Abstract

The embodiment of the utility model discloses a lightning stroke surge protection circuit and a circuit board, and relates to the field of protection circuits, and the lightning stroke surge protection circuit comprises a lightning stroke surge protection module, a rectification filtering module, a residual voltage protection module and a load module. Wherein the power supply input end is connected with the input end of the lightning stroke surge protection module, the output end of the lightning stroke surge protection module is connected with the input end of the rectification filtering module, and the lightning stroke surge protection module absorbs lightning stroke surge voltage input from the power supply input end to obtain first reduced voltage; the first step-down voltage is transmitted to the rectification filtering module through the output end of the lightning stroke surge protection module. By adopting the embodiment of the invention, a good protection effect can be provided when lightning surge occurs in the circuit, and the accuracy is higher.

Description

Technical Field

[0001] The present application relates to the field of protection circuits, and in particular to a lightning surge protection circuit and a circuit board. Background Art

[0002] It is a common protection method to equip electronic equipment with a lightning surge protection circuit. The purpose is to prevent the current surge caused by lightning from damaging the equipment. The lightning surge protection circuit can suppress the surge voltage and pulse voltage generated instantly by the equipment, and conduct the shunt in a very short time, playing an important role in the circuit.

[0003] Traditional lightning surge protection circuits usually use a protection circuit and an absorption capacitor in parallel to provide lightning surge protection. However, even with the protection circuit, a forward lightning surge will still bring high residual voltage, which may exceed the withstand voltage of the capacitor or semiconductor components in the secondary circuit, causing damage to the above components. Utility Model Content

[0004] The embodiment of the present application provides a lightning surge protection circuit and a circuit board, which can provide good protection against lightning surges in the circuit with higher accuracy. The technical solution is as follows:

[0005] In a first aspect, an embodiment of the present application provides a lightning surge protection circuit, and a method includes:

[0006] Lightning surge protection module, rectifier filter module, residual voltage protection module and load module;

[0007] The power input end is connected to the input end of the lightning surge protection module, the output end of the lightning surge protection module is connected to the input end of the rectifier and filter module, the lightning surge protection module absorbs the lightning surge voltage input from the power input end to obtain a first step-down voltage, and the first step-down voltage is transmitted to the rectifier and filter module via the output end of the lightning surge protection module;

[0008] The output end of the rectifying and filtering module is connected to the input end of the residual voltage protection module. The rectifying and filtering module rectify and filters the first step-down voltage to obtain a filtered voltage. The filtered voltage is transmitted to the residual voltage protection module via the output end of the rectifying and filtering module.

[0009] The output end of the residual voltage protection module is connected to the input end of the load module. The residual voltage protection module steps down the filtered voltage to obtain a second stepped-down voltage. The second stepped-down voltage is transmitted to the load module via the input end of the residual voltage protection module so that the load module works based on the second stepped-down voltage.

[0010] In a second aspect, an embodiment of the present application provides a circuit board, and the circuit board includes the lightning surge protection circuit as described in the first aspect.

[0011] The beneficial effects brought about by the technical solutions provided by some embodiments of the present application include at least:

[0012] The lightning surge protection circuit provided by the present application includes: a lightning surge protection module, a rectifier filter module, a residual voltage protection module and a load module. The residual voltage protection module is used to reduce the filter voltage to obtain a second reduced voltage when the filter voltage obtained based on the lightning surge voltage is higher than a preset threshold, so that the load module works based on the second reduced voltage. In other words, the lightning surge protection circuit provided by the present application can provide good protection when a lightning surge occurs, and the components included in the residual voltage protection module are selected through formula calculation, so as to ensure that the load module can work safely without being damaged. The lightning surge protection has higher accuracy and reliability, and is suitable for circuits with higher requirements for lightning surge protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 It is a structural schematic diagram of an existing cumulative surge protection circuit provided in an embodiment of the present application;

[0015] Figure 2 It is a structural schematic diagram of a lightning surge protection circuit provided in an embodiment of the present application;

[0016] Figure 3 It is a structural schematic diagram of a lightning surge protection circuit provided in an embodiment of the present application;

[0017] Figure 4 It is a structural schematic diagram of a lightning surge protection circuit provided in an embodiment of the present application;

[0018] Figure 5 It is a structural schematic diagram of a lightning surge protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In the description of the present application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are an "or" relationship.

[0021] The present application is described in detail below with reference to specific embodiments.

[0022] like Figure 1 , which is a schematic diagram of a lightning surge protection circuit in the prior art, the lightning surge protection circuit includes a lightning surge protection module 102, a rectifier filter module 103 and a load module 104. The power input terminal 101 is connected to the input terminal of the lightning surge protection module 102, the output terminal of the lightning surge protection module 102 is connected to the input terminal of the rectifier filter module 103, and the output terminal of the rectifier filter module 103 is connected to the input terminal of the load module 104.

[0023] The lightning surge protection module 102 can suppress the surge voltage and pulse voltage generated instantly by the equipment, and conduct the shunt in a very short time to prevent the current surge during lightning strike from causing damage to the equipment. For example, the lightning surge protection module 102 includes a varistor, a thermistor, and a gas discharge tube. Among them, the varistor has the characteristics of fast response, high sensitivity and low impedance, and can effectively absorb and disperse excess energy to protect the system from the impact of transient voltage. The thermistor is a temperature-sensitive resistor that can automatically cut off the power supply when the temperature rises, thereby preventing overheating from causing damage to the system. The gas discharge tube has the characteristics of high withstand voltage, large capacity and low impedance, and can effectively absorb and disperse excess energy to protect the system from the impact of transient current.

[0024] The selection of the thermistor depends on the requirement of the surge current when the power is input to the power input terminal 101 , so the selection adjustment space of the thermistor is relatively small. Figure 1The circuit shown has a good protection circuit for lightning surge voltages of 4kV and below. However, there are application scenarios with higher requirements for lightning surges, such as the 6kV or even 8kV lightning surge voltage generated by the power supply of a PoE switch. Figure 1 The protection circuit shown is not adequate.

[0025] This is because common varistors such as TVR14561-D, TVR1461-D, and TVR1681-D are provided with a maximum limiting voltage and a maximum continuous operating voltage, and the maximum limiting voltage is the maximum residual voltage generated by the varistor when subjected to a lightning surge voltage. When subjected to a lightning surge voltage of 6kV or even 8kV, the maximum continuous operating voltages of TVR14561-D, TVR1461-D, and TVR1681-D are 930V, 1020V, and 1120V, respectively, which far exceed the withstand voltage values ​​(commonly 600V, 650V, and 700V) of semiconductor components in the load module 104, resulting in the residual voltage generated by the lightning surge voltage damaging the components of the load module 104.

[0026] Based on the above problems, the present application proposes a lightning surge protection circuit to solve them. Figure 2 As shown, it is a schematic diagram of a lightning surge protection circuit proposed in the present application, and the lightning surge protection circuit includes a lightning surge protection module 202, a rectifier and filter module 203, a residual voltage protection module 204, and a load module 205. Among them, the power input end 201 is connected to the input end of the lightning surge protection module 202, the output end of the lightning surge protection module 202 is connected to the input end of the rectifier and filter module 203, the output end of the rectifier and filter module 203 is connected to the input end of the residual voltage protection module 204, and the output end of the residual voltage protection module 204 is connected to the input end of the load module 205.

[0027] Based on the structure of the lightning surge protection circuit provided in the present application, the lightning surge protection module 202 absorbs the lightning surge voltage input from the power supply input terminal 201 to obtain a first stepped-down voltage, and the first stepped-down voltage is transmitted to the rectification and filtering module 203 via the output terminal of the lightning surge protection module 202; the rectification and filtering module 203 rectifies and filters the first stepped-down voltage to obtain a filtered voltage, and the filtered voltage is transmitted to the residual voltage protection module 204 via the output terminal of the rectification and filtering module 203; the residual voltage protection module 204 steps down the filtered voltage to obtain a second stepped-down voltage, and the second stepped-down voltage is transmitted to the load module 205 via the input terminal of the residual voltage protection module 204, so that the load module 205 operates based on the second stepped-down voltage.

[0028] Specifically, the lightning surge protection module 202 is used to absorb the lightning surge voltage to obtain a first step-down voltage when receiving the lightning surge voltage through the power input terminal 201, and send the first step-down voltage to the rectifier and filter module 203. The power input terminal 201 can be a battery device or an interface device for accessing an external voltage. For example, the power input terminal 201 is an interface of a battery device. A battery is a device that can convert chemical energy into electrical energy. Specifically, a battery is a cup-shaped container, a trough-shaped container, or a container of other shapes including an electrolyte solution and a metal electrode. The metal electrode generates current under the action of the electrolyte solution to provide electrical energy to the load. The types of batteries include but are not limited to dry batteries, lead-acid batteries, lithium batteries, etc. For another example, the power input terminal 201 is an interface device for connecting 220V AC power to an overcurrent protection circuit, including an interface device for components such as a transformer and a power management chip.

[0029] The rectifier and filter module 203 is used to rectify and filter the first step-down voltage to obtain a filter voltage, and send the filter voltage to the load module 205. Specifically, the rectifier and filter module 203 converts the AC power into DC power based on the first step-down voltage, and removes the AC component therein, which is mainly achieved by a rectifier or a rectifier unit, which can convert the AC power into pulsating DC power, and smooth the pulsating DC power into stable DC power. For example, the rectifier and filter module 203 includes a rectifier or a rectifier unit, a filter, and a protection circuit to ensure its reliability and stability.

[0030] The residual voltage protection module 204 is used to reduce the filtered voltage to obtain a second reduced voltage when the filtered voltage is higher than a preset threshold, and send the second reduced voltage to the load module 205. Specifically, when the filtered voltage of the lightning surge voltage after absorption and filtering is higher than the preset threshold, the residual voltage protection module 204 absorbs the filtered voltage to reduce the voltage value of the filtered voltage to the voltage value of the second reduced voltage, so that the load module 205 works according to the second reduced voltage.

[0031] The lightning surge protection circuit provided by the present application includes: a lightning surge protection module, a rectifier filter module, a residual voltage protection module and a load module. The residual voltage protection module is used to reduce the filter voltage to obtain a second reduced voltage when the filter voltage obtained based on the lightning surge voltage is higher than a preset threshold, so that the load module works based on the second reduced voltage. In other words, the lightning surge protection circuit provided by the present application can provide good protection when a lightning surge occurs, and the components included in the residual voltage protection module are selected through formula calculation, so as to ensure that the load module can work safely without being damaged. The lightning surge protection has higher accuracy and reliability, and is suitable for circuits with higher requirements for lightning surge protection.

[0032] like Figure 3, which is a schematic diagram of a lightning surge protection circuit proposed in the present application, and the lightning surge protection circuit includes a lightning surge protection module 302, a rectifier filter module 303, a residual voltage protection module 304, and a load module 305. The connection structure of the lightning surge protection module 302, the rectifier filter module 303, the residual voltage protection module 304, and the load module 305 is as shown in FIG. Figure 2 As shown, no further description is given here.

[0033] The residual voltage protection module 304 includes a voltage stabilizing unit 3042 and a switch unit 3041. The input end of the voltage stabilizing unit 3042 is connected to the power input end 301, the output end of the voltage stabilizing unit 3042 is connected to the input end of the switch unit 3041, and the output end of the switch unit 3041 is connected to the input end of the load module 305.

[0034] When the filtered voltage is higher than the preset threshold, the switch unit 3041 switches from the off state to the on state. Based on the switch unit 3041 being in the on state, the voltage stabilizing unit 3042 absorbs the filtered voltage to obtain a residual voltage. The sum of the residual voltage and the on-voltage corresponding to the switch unit 3041 being in the on state is transmitted to the load module through the output end of the switch unit 3041 as the second step-down voltage.

[0035] Specifically, the switch unit 3041 is used to switch from the off state to the on state when the filtering voltage is higher than a preset threshold, and the on voltage of the switch unit in the on state is lower than the off voltage of the switch unit in the off state.

[0036] The voltage stabilizing unit 3042 is used to absorb the filtered voltage based on the switch unit in the on state to obtain the residual voltage, and the voltage value of the second step-down voltage is the sum of the voltage values ​​of the on voltage and the residual voltage.

[0037] The preset threshold is the working voltage threshold of the switch unit 3041 and the voltage stabilizing unit 3042 connected in series. When the filter voltage applied to the residual voltage protection module 304 is higher than the preset threshold, the switch unit 3041 switches from the off state to the on state. The on voltage of the switch unit 3041 in the on state is much lower than the off voltage of the switch unit 3041 in the off state, as shown in the following formula:

[0038] V ST =V MOV1-DC +V BS1-S ;

[0039] Among them, V ST is the operating voltage threshold of the switch unit 3041 and the voltage stabilizing unit 3042 connected in series, V MOV1-DC is the operating voltage of the voltage stabilizing unit 3042, V BS1-Sis the maximum off-state voltage of the switch unit 3041.

[0040] As shown in the following formula:

[0041] V in =V MOV1-P +V BS1-T ;

[0042] V in When the lightning surge protection circuit is subjected to the lightning surge voltage, the maximum input voltage of the load module 305, that is, the voltage value of the second step-down voltage, V MOV1-P V is the residual voltage of the voltage stabilizing unit 3042 when it withstands the lightning surge voltage, that is, the voltage value of the residual voltage obtained after absorbing the filtered voltage. BS1-T is the on-state voltage of the switch unit 3041.

[0043] When the switch unit 4031 switches from the off state to the on state, the on voltage V BS1-T The voltage value is small, V in is reduced to the residual voltage and the conduction voltage V of the voltage stabilizing unit 3042 that bears the lightning surge voltage. BS1-T The sum of the second regulated voltage and the second stepped-down voltage is also called the second stepped-down voltage, and the voltage value of the second regulated voltage must be less than or equal to the maximum operating voltage of the load module, thereby ensuring that the load module 305 operates based on the second stepped-down voltage with a lower voltage value without being damaged.

[0044] based on Figure 3 The schematic diagram of the lightning surge protection circuit is shown in Figure 4 As shown, it is a schematic diagram of a lightning surge protection circuit proposed in the present application, the voltage stabilizing unit 3042 includes a varistor MOV1, a first end of the varistor MOV1 is connected to the first end of the power input terminal 301, and a second end of the varistor MOV1 is connected to the input end of the switch unit 3041.

[0045] The switch unit 3041 includes: a semiconductor switch discharge element BS1. The first end of the semiconductor switch discharge element BS1 is connected to the output end of the switch unit 3041, and the second end of the semiconductor switch discharge element BS1 is connected to the second end of the power input end. The semiconductor switch discharge element is a special type of electronic component, which is usually composed of a layer of semiconductor material sandwiched between two metal electrodes. The characteristics of the semiconductor are used to control the discharge process, and the electrical energy can be effectively converted into other forms of energy, such as light energy, heat energy, etc.

[0046] In this embodiment, the lightning surge protection module 302 is also used to send an input voltage to the residual voltage protection module 304 when an input voltage with a voltage value within a normal range is received through the power input terminal 301; based on the input voltage, the switch unit 3041 is in an off state, and the sum of the voltage values ​​of the working voltage and the off voltage of the voltage stabilizing unit 3042 is the voltage value of the DC voltage corresponding to the input voltage.

[0047] For example, the varistor MOV1 as the voltage stabilizing unit 3042 can be selected as a varistor with a lower specification than TVR14561-D, TVR1461-D, and TVR1681-D, such as TVR14271-D. The maximum continuous working voltage of TVR14271-D is 225V, and the maximum limiting voltage, that is, the residual voltage after receiving the lightning surge voltage, is 455V. The semiconductor switch discharge element BS1 as the switch unit 3041 can be selected with a maximum voltage of V before opening. BS1-S =260V components, this combination selection meets the power supply design requirements of 90Vac-264Vac AC input voltage range. Therefore, based on the input voltage, the working voltage of the voltage stabilizing unit 3042 is less than or equal to the maximum continuous working voltage of the voltage stabilizing unit, so that when the input voltage value is within the normal range received through the power input terminal 301, the voltage stabilizing unit 3042 works normally and the switch unit 3041 is in the off state.

[0048] And using a single TVR14271-D varistor cannot meet the requirements, because when the input is 264Vac, the corresponding DC voltage is 374V, which exceeds the V MOV1-DC =225V, which will cause the varistor MOV1 to fail.

[0049] The lightning surge protection circuit provided by the present application includes: a lightning surge protection module, a rectifier filter module, a residual voltage protection module and a load module. The residual voltage protection module is used to reduce the filter voltage to obtain a second reduced voltage when the filter voltage obtained based on the lightning surge voltage is higher than a preset threshold, so that the load module works based on the second reduced voltage. In other words, the lightning surge protection circuit provided by the present application can provide good protection when a lightning surge occurs, and the components included in the residual voltage protection module are selected through formula calculation, so as to ensure that the load module can work safely without being damaged. The lightning surge protection has higher accuracy and reliability, and is suitable for circuits with higher requirements for lightning surge protection.

[0050] like Figure 5, which is a schematic diagram of a lightning surge protection circuit proposed in the present application, the lightning surge protection circuit includes: a lightning surge protection module 402 , a rectification and filtering module 403 , a residual voltage protection module 404 , and a load module 405 .

[0051] The lightning surge protection module includes 402: a thermistor NTC, a second varistor MOV2, a third varistor MOV3, a fourth varistor MOV4 and a gas discharge tube GDT;

[0052] The first end of the second varistor MOV2 and the first end of the third varistor MOV3 are respectively connected to the first end of the power input terminal 401, the first end of the thermistor NTC is connected to the second end of the power input terminal 401, the second end of the thermistor NTC is respectively connected to the second end of the second varistor MOV2 and the first end of the fourth varistor MOV4, the second end of the third varistor MOV3 and the second end of the fourth varistor MOV4 are respectively connected to the first end of the gas discharge tube GDT, and the second end of the gas discharge tube GDT is grounded.

[0053] The rectification and filtering module 403 includes: a fuse F, a first capacitor C1, a transformer LC, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a rectification unit;

[0054] The first end of the fuse F is connected to the first end of the power input terminal 401, the second end of the fuse F is respectively connected to the input end of the lightning surge protection module 402, the first end of the first capacitor C1, and the first end of the transformer LC, the second end of the first capacitor C1 and the second end of the transformer LC are respectively connected to the output end of the lightning surge protection module 402, the third end of the transformer LC is respectively connected to the first end of the second capacitor C2 and the first end of the rectifier unit, the fourth end of the transformer LC is connected to the first end of the third capacitor C3, the second end of the second capacitor C2 is connected to the second end of the third capacitor C3 and then grounded, the second end of the rectifier unit is respectively connected to the input end of the residual voltage protection module 404, the first end of the fourth capacitor C4, and the input end of the load module 404, the third end of the rectifier unit is connected to the fourth end of the transformer LC, and the fourth end of the rectifier unit is respectively connected to the output end of the residual voltage protection module 404, the second end of the fourth capacitor C4, and the second end of the load module 404.

[0055] The rectifier unit includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4, and the anode of the fourth diode D4 is connected to the anode of the first diode D1.

[0056] The structure and working principle of the residual pressure protection module 404 refer to Figure 3 and Figure 5 As shown, no further description is given here.

[0057] The lightning surge protection circuit provided by the present application includes: a lightning surge protection module, a rectifier filter module, a residual voltage protection module and a load module. The residual voltage protection module is used to reduce the filter voltage to obtain a second reduced voltage when the filter voltage obtained based on the lightning surge voltage is higher than a preset threshold, so that the load module works based on the second reduced voltage. In other words, the lightning surge protection circuit provided by the present application can provide good protection when a lightning surge occurs, and the components included in the residual voltage protection module are selected through formula calculation, so as to ensure that the load module can work safely without being damaged. The lightning surge protection has higher accuracy and reliability, and is suitable for circuits with higher requirements for lightning surge protection.

[0058] In one embodiment, the present application also provides a circuit board, the circuit board comprising: Figure 2-Figure 5 Any of the lightning surge protection circuits shown. It can be understood that the circuit board provided in the embodiment of the present application can be a whole circuit board, or can be formed by splicing multiple circuit boards.

[0059] The circuit board including the lightning surge protection circuit provided in the present application can provide good protection when a lightning surge occurs, and the components included in the residual voltage protection module are selected through formula calculation, thereby ensuring that the load module can work safely without being damaged. The lightning surge protection has higher accuracy and reliability, and is suitable for circuits with higher requirements for lightning surge protection.

[0060] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A lightning surge protection circuit, characterized in that: The circuit comprises: Lightning surge protection module, rectifier filter module, residual voltage protection module and load module; The power input end is connected to the input end of the lightning surge protection module, the output end of the lightning surge protection module is connected to the input end of the rectifier and filter module, the lightning surge protection module absorbs the lightning surge voltage input from the power input end to obtain a first step-down voltage, and the first step-down voltage is transmitted to the rectifier and filter module via the output end of the lightning surge protection module; The output end of the rectifying and filtering module is connected to the input end of the residual voltage protection module, the rectifying and filtering module rectify and filters the first step-down voltage to obtain a filtered voltage, and the filtered voltage is transmitted to the residual voltage protection module via the output end of the rectifying and filtering module; The output end of the residual voltage protection module is connected to the input end of the load module, and the residual voltage protection module steps down the filtered voltage to obtain a second stepped-down voltage. The second stepped-down voltage is transmitted to the load module via the input end of the residual voltage protection module, so that the load module operates based on the second stepped-down voltage.

2. The lightning surge protection circuit according to claim 1, characterized in that: The residual voltage protection module includes: a voltage stabilizing unit and a switch unit; The input end of the voltage stabilizing unit is connected to the input end of the power supply, the output end of the voltage stabilizing unit is connected to the input end of the switch unit, and the output end of the switch unit is connected to the input end of the load module; When the filtered voltage is higher than a preset threshold, the switch unit switches from an off state to an on state. Based on the switch unit being in the on state, the voltage stabilizing unit absorbs the filtered voltage to obtain a residual voltage. The sum of the residual voltage and the on voltage corresponding to the switch unit being in the on state is transmitted to the load module through the output end of the switch unit as the second step-down voltage.

3. The lightning surge protection circuit according to claim 2, characterized in that: The voltage stabilizing unit includes a varistor; The first end of the varistor is connected to the power input end, and the second end of the varistor is connected to the input end of the switch unit.

4. The lightning surge protection circuit according to claim 2, characterized in that: The switch unit comprises: a semiconductor switch discharge element; The first end of the semiconductor switch discharge element is connected to the output end of the voltage stabilizing unit, and the second end of the semiconductor switch discharge element is connected to the input end of the load module.

5. The lightning surge protection circuit according to claim 1, characterized in that: The lightning surge protection module comprises: a thermistor, a second varistor, a third varistor, a fourth varistor and a gas discharge tube; The first end of the second varistor and the first end of the third varistor are respectively connected to the power input end, the first end of the thermistor is connected to the power input end, the second end of the thermistor is respectively connected to the second end of the second varistor and the first end of the fourth varistor, the second end of the third varistor and the second end of the fourth varistor are respectively connected to the first end of the gas discharge tube, and the second end of the gas discharge tube is grounded.

6. The lightning surge protection circuit according to claim 1, characterized in that: The rectification and filtering module comprises: a fuse, a first capacitor, a transformer, a second capacitor, a third capacitor, a fourth capacitor and a rectification unit; The first end of the fuse is connected to the first end of the power input end, the second end of the fuse is respectively connected to the input end of the lightning surge protection module, the first end of the first capacitor, and the first end of the transformer, the second end of the first capacitor and the second end of the transformer are respectively connected to the output end of the lightning surge protection module, the third end of the transformer is respectively connected to the first end of the second capacitor and the first end of the rectifier unit, the fourth end of the transformer is connected to the first end of the third capacitor, the second end of the second capacitor is connected to the second end of the third capacitor and then grounded, the second end of the rectifier unit is respectively connected to the input end of the residual voltage protection module, the first end of the fourth capacitor, and the input end of the load module, the third end of the rectifier unit is connected to the fourth end of the transformer, and the fourth end of the rectifier unit is respectively connected to the output end of the residual voltage protection module, the second end of the fourth capacitor, and the second end of the load module.

7. The lightning surge protection circuit according to claim 6, characterized in that: The rectifying unit comprises a first diode, a second diode, a third diode and a fourth diode; The cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is connected to the cathode of the third diode, the anode of the third diode is connected to the cathode of the fourth diode, and the anode of the fourth diode is connected to the anode of the first diode.

8. A circuit board, characterized in that: The circuit board includes the lightning surge protection circuit as described in any one of claims 1-7.

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