Surge protector and trigger circuit

Abstract

The utility model discloses a surge protector and a trigger circuit, the trigger circuit comprises an overvoltage protection module and an RC branch circuit, the overvoltage protection module comprises at least two switch-type devices and at least two impedance branch circuits, and two ends of the two switch-type devices are electrically connected with a first end and a second end of the trigger circuit respectively after the two switch-type devices are connected in series; the two impedance branches are connected in parallel with the two switch-type devices in a one-to-one correspondence manner, or one impedance branch is connected in parallel with one switch-type device, and the other impedance branch is connected in parallel with the two ends of the two switch-type devices; and the RC branch circuit is connected in parallel to two ends of one switch-type device or / and two ends of two switch-type devices. The circuit is combined with an overvoltage protection module and an RC branch circuit, residual voltage after a switch type device is conducted is reduced through resistor and capacitor voltage division, and the circuit is protected; the tolerance of the circuit to transient high voltage is improved by the gas discharge tube and the RC branch, and the reliability is enhanced; low-cost elements and various packaging modes are adopted, the application range is wide, and stable and safe signals are ensured.

Description

Technical Field

[0001] This utility model relates to the field of surge protection devices, and in particular to a surge protector and triggering circuit. Background Technology

[0002] With the rapid development of electronic technology, electronic devices are becoming increasingly sensitive to voltage fluctuations. Surge protectors (SPDs) play a crucial role in protecting electronic equipment from damage caused by lightning and electrical surges. The main function of a surge protector is to withstand overvoltage surges in a circuit, limiting the overvoltage to a level that the equipment can safely withstand, thereby protecting the electronic equipment from damage.

[0003] However, existing surge protectors have significant shortcomings in addressing residual voltage and withstand voltage issues. Residual voltage, the voltage across the surge protector when it is in the conducting state, is one of the key indicators for evaluating its performance. Excessive residual voltage may damage the protected equipment, while insufficient withstand voltage means that the surge protector may fail and lose its protective function when subjected to large surge currents.

[0004] Furthermore, the high cost of electronic components required by existing surge protector solutions not only increases the cost of the final product but also limits the widespread adoption of surge protectors in cost-sensitive applications. For example, some high-performance surge protectors require the use of special semiconductor devices, such as transient voltage suppressor diodes, which are relatively expensive and less cost-effective in high-volume applications.

[0005] To address the aforementioned issues, this application proposes a novel surge protector designed to reduce residual voltage and improve withstand voltage performance, while simultaneously reducing reliance on high-cost electronic components. Through innovative design and material selection, this invention aims to achieve lower residual voltage and higher withstand voltage performance, while reducing overall cost, making the surge protector more economical and efficient, and suitable for a wider range of applications. Utility Model Content

[0006] In view of this, the present invention addresses the deficiencies of the existing technology, and its main purpose is to provide a surge protector and trigger circuit. This trigger circuit combines overvoltage protection and RC branch to reduce residual voltage, improve withstand voltage and reliability, has low cost, supports multiple packaging forms, and is widely used in communication, power supply, signal processing and other fields.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A trigger circuit includes an overvoltage protection module and an RC branch. The overvoltage protection module includes at least two switching devices and at least two impedance branches. The two ends of the two switching devices connected in series are electrically connected to a first terminal and a second terminal of the trigger circuit, respectively. The two impedance branches are connected in parallel with the two switching devices in a one-to-one correspondence, or one impedance branch is connected in parallel with one of the switching devices, and the other impedance branch is connected in parallel across the two switching devices. The RC branch is connected in parallel across one of the switching devices and / or in parallel across both switching devices.

[0009] As a preferred embodiment, it also includes a varistor connected in series between the first terminal of the trigger circuit and the two switching devices, and the RC branch includes a resistor and a capacitor connected in series, and the RC branch is connected in parallel across one of the switching devices.

[0010] As a preferred embodiment, it also includes a varistor connected in series between the first terminal of the trigger circuit and the two switching devices. The RC branch includes a resistor and a capacitor connected in series, and the RC branch is connected in parallel across one of the switching devices. One impedance branch is connected in parallel with one of the switching devices, and the other impedance branch is connected in parallel across both switching devices.

[0011] As a preferred embodiment, the circuit includes three switching devices and three impedance branches, with each impedance branch corresponding to one of the three switching devices and connected in parallel. Each RC branch includes two sets of resistors and capacitors connected in series, one set connected in parallel with one of the switching devices, and the other set connected in parallel with the two switching devices. It also includes a varistor connected in series between the first terminal of the trigger circuit and the three switching devices.

[0012] As a preferred embodiment, the circuit includes three switching devices and three impedance branches, wherein two impedance branches are connected in parallel with two switching devices in a one-to-one correspondence; the other impedance branch is connected in parallel with the two ends of the two switching devices; the RC branch includes two sets of resistors and capacitors connected in series, one set of which is connected in parallel with the two ends of one switching device; the other set is connected in parallel with the two ends of the two switching devices; and a varistor is also included, which is connected in series between the first terminal of the trigger circuit and the three switching devices.

[0013] As a preferred embodiment: the switching device is a gas discharge tube and / or a semiconductor discharge tube, and all switching devices are of the same model.

[0014] As a preferred embodiment, the RC branch includes resistors and capacitors connected in series with each other.

[0015] As a preferred option, the capacitor in the RC branch is a pF level capacitor.

[0016] As a preferred embodiment, the impedance branches are resistors, and the resistance values ​​of each impedance branch are the same.

[0017] A surge protector comprising the aforementioned trigger circuit.

[0018] Compared with existing technologies, this invention has significant advantages and beneficial effects. Specifically, as can be seen from the above technical solution, by employing an overvoltage protection module and an RC branch to form a trigger circuit, this circuit utilizes the voltage division effect of resistors and capacitors to effectively reduce the residual voltage after the gas discharge tube is turned on, protecting subsequent circuits. The gas discharge tube and RC branch improve the circuit's tolerance to transient high voltages, achieving higher withstand voltage. Simultaneously, the gas discharge tube provides protection against transient high voltages, enhancing the circuit's reliability. Furthermore, the components in this circuit are inexpensive and support both surface-mount and through-hole packages, providing designers with flexibility and facilitating wide application in various fields such as communication, power supply, and signal processing, providing stable and effective signal protection.

[0019] To more clearly illustrate the structural features and effects of this utility model, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the circuit structure of the first embodiment of the present utility model;

[0021] Figure 2 This is a schematic diagram of the circuit structure after connecting a varistor in series according to the first embodiment of this utility model;

[0022] Figure 3 This is a schematic diagram of the circuit structure of the second embodiment of the present utility model;

[0023] Figure 4 This is a schematic diagram of the circuit structure after connecting a varistor in series according to the second embodiment of this utility model;

[0024] Figure 5 This is a schematic diagram of the circuit structure of the third embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the circuit structure after connecting a varistor in series according to the third embodiment of this utility model;

[0026] Figure 7 This is a schematic diagram of the circuit structure of the fourth embodiment of the present utility model;

[0027] Figure 8This is a schematic diagram of the circuit structure after connecting a varistor in series according to the fourth embodiment of this utility model. Detailed Implementation

[0028] This utility model is as follows Figures 1 to 8 As shown, a surge protector and trigger circuit are disclosed. The trigger circuit includes an overvoltage protection module and an RC branch, wherein:

[0029] The overvoltage protection module includes at least two switching devices and at least two impedance branches. The two ends of the two switching devices connected in series are electrically connected to the first and second ends of the trigger circuit, respectively. The switching devices are gas discharge tubes and / or semiconductor discharge tubes; in this application, the switching devices are gas discharge tubes. The two impedance branches are connected in parallel with the two switching devices in a one-to-one correspondence, or one impedance branch is connected in parallel with one of the switching devices, and the other impedance branch is connected in parallel across the two switching devices. The impedance branches are resistors. The RC branches are connected in parallel across one of the switching devices and / or across both switching devices. The RC branches include a resistor and a capacitor connected in series.

[0030] As a first implementation method, see attached Figure 1 As shown, the overvoltage protection module includes a gas discharge tube G1, a gas discharge tube G2, resistors R1 and R2, and a resistor R3 and a capacitor C1 connected in series on the RC branch. Gas discharge tubes G1 and G2 are of the same type, resistors R1 and R2 are of the same value, and resistors R3 and C1 are used for triggering (capacitor C1 is a pF level capacitor, and the resistance of resistor R3 is much smaller than that of resistors R1 and R2). The two ends of the series connection between gas discharge tubes G1 and G2 are electrically connected to the first and second ends of the trigger circuit, respectively. Resistor R1 is connected in parallel with gas discharge tube G1, and resistor R2 is connected in parallel with gas discharge tube G2. The two ends of the RC branch are connected in parallel with resistor R2 and the two ends of gas discharge tube G2, respectively.

[0031] Under normal AC operating voltage, gas discharge tubes G1 and G2 maintain a high impedance or open circuit state, are non-conductive, and allow current to flow through resistors R1 and R2. During the withstand voltage test, due to the very small capacitance of capacitor C1 and the very low operating voltage frequency, according to the formula Xc = 1 / 2πfc, the capacitive reactance across capacitor C1 is very large. The capacitive reactance of capacitor C1 plus the resistance of resistor R3 is much greater than the resistance of resistor R2. At this time, the total resistance of resistor R2, resistor R3 in the RC branch, and capacitor C1 connected in parallel is close to the resistance of resistor R2. Since the resistance of gas discharge tube G2 is much greater than that of resistor R2, the sum of the total resistance of resistor R2, gas discharge tube G2, and resistor R3 + capacitor C1 in the RC branch is approximately equal to the resistance of resistor R2. Similarly, the sum of the resistances of resistor R1 and gas discharge tube G1 is approximately equal to the resistance of resistor R1. Because resistors R1 and R2 are of the same value, equal impedance and equal voltage division are achieved between the two gas discharge tubes G1 and G2. When this trigger circuit is used in series with a varistor MOV (as shown in the attached diagram), Figure 2 As shown in the diagram, this circuit avoids the situation where the resistance of the gas discharge tube is much greater than that of the varistor, resulting in a large voltage difference between the gas discharge tube and the varistor. This prevents the varistor from distributing a certain proportion of voltage, which in turn causes the entire trigger circuit to conduct prematurely due to insufficient withstand voltage. This trigger circuit can achieve proportional voltage division between the gas discharge tubes G1 and G2 and the varistor MOV, thereby greatly improving the circuit's withstand voltage capability.

[0032] When a transient surge voltage appears in the input voltage signal, the surge voltage is generally a rapidly changing interference signal on the order of μs. At this time, the frequency of the interference signal is particularly high. According to the formula Xc = 1 / 2πfc, capacitor C1 is approximately short-circuited, and the total resistance of the RC branch is R3. Therefore, the total resistance of the parallel connection between resistor R2, gas discharge tube G2, and the RC branch is approximately equal to resistor R3. Since the total resistance of the parallel connection between gas discharge tube G1 and resistor R1 is approximately equal to the resistance of resistor R1, and the resistance of resistor R3 is much smaller than that of resistor R1, the surge voltage is mainly concentrated on gas discharge tube G1, forcing it to conduct prematurely. After gas discharge tube G1 conducts, its impedance rapidly decreases, and the surge voltage begins to concentrate on gas discharge tube G2. Gas discharge tube G2 then conducts, and its resistance rapidly decreases. Finally, the entire trigger circuit conducts, guiding the surge voltage to ground, thus protecting the subsequent circuits from damage. This step-by-step conduction trigger circuit largely avoids the residual voltage superposition effect caused by the simultaneous conduction of gas discharge tubes G1 and G2, significantly reducing the overall residual voltage of the circuit and making the protected end safer. When this trigger circuit is used in series with a varistor MOV, resistor R3 can generate a certain voltage difference with the varistor MOV, allowing gas discharge tube G2 to conduct preferentially before the varistor MOV, avoiding the superposition of residual voltage between gas discharge tube G2 and varistor MOV. This implementation is suitable for high withstand voltage and low contact voltage applications. Combined with a varistor, it improves the circuit's withstand voltage capability and avoids the superposition effect of residual voltage leading to excessively high residual voltage.

[0033] As a second implementation method, see attached Figure 3 The diagram shows an improvement upon the first embodiment. Specifically, similar to the first embodiment, the trigger circuit consists of a gas discharge tube G1, a gas discharge tube G2, resistors R1 and R2, and a resistor R3 and capacitor C1 connected in series on the RC branch. The RC branch is connected in parallel across the gas discharge tube G2, resistor R2 is connected in parallel across the gas discharge tube G1, and resistor R1 is connected in parallel across both gas discharge tubes G1 and G2. Capacitor C1 is a pF-level capacitor, and the resistance of resistor R3 is much smaller than that of resistors R1 and R2, while the resistance of resistor R1 is also much smaller than that of resistor R2.

[0034] Under normal operating voltage, gas discharge tubes G1 and G2 maintain a high impedance or open circuit state, are non-conductive, and allow current to flow through resistors R1 and R2. During the withstand voltage test, gas discharge tubes G1 and G2 achieve equal voltage division, and also achieve proportional voltage division with the varistor MOV (as shown in the attached figure). Figure 4As shown in the diagram, this improves the circuit's withstand voltage capability. When a transient surge voltage appears in the input voltage signal, firstly, gas discharge tube G1 conducts, then gas discharge tube G2 conducts, and finally the varistor MOV conducts, discharging the amplified current and guiding the surge voltage to ground, thereby protecting subsequent circuits from damage. This step-by-step conduction characteristic avoids residual voltage superposition, significantly reducing the residual voltage and absorbing more surge energy, thus improving the circuit's protection capability. Unlike the first implementation method, this trigger circuit can generate a larger voltage difference between gas discharge tubes G1 and G2 when facing a surge voltage, thereby further reducing the residual voltage superposition between gas discharge tubes G1 and G2 and lowering the residual voltage even further.

[0035] As a third implementation method, see attached Figure 5 The diagram shown is a derivative improvement based on the first embodiment. Specifically, the trigger circuit consists of gas discharge tubes G1, G2, and G3, resistors R1, R2, and R3, and two RC branches. One RC branch consists of capacitor C1 and resistor R4 connected in parallel across gas discharge tubes G2 and G3. The other RC branch consists of capacitor C2 and resistor R5 connected in parallel across gas discharge tube G3. Furthermore, resistor R1 is connected in parallel across gas discharge tube G1, resistor R2 is connected in parallel across gas discharge tube G2, and resistor R3 is connected in parallel across gas discharge tube G3. Resistors R1, R2, and R3 are of the same value, gas discharge tubes G1, G2, and G3 are of the same model, and capacitors C1 and C2 are pF level capacitors, with capacitor C1 being larger than capacitor C2. Resistors R4 and R5 are much smaller than resistors R1, R2, and R3.

[0036] Under normal operating voltage, gas discharge tubes G1, G2, and G3 maintain a high impedance or open circuit state, are non-conductive, and allow current to flow through resistors R1, R2, and R3. During the withstand voltage test, gas discharge tubes G1, G2, and G3 achieve equal voltage division, and can achieve a certain proportion of voltage division with the varistor MOV, thereby improving the circuit's withstand voltage capability. When a transient surge voltage appears in the input voltage signal, gas discharge tube G1 turns on first, followed by gas discharge tube G2, then gas discharge tube G3, and finally the varistor MOV turns on (as shown in the attached diagram). Figure 6As shown, the surge current is discharged, guiding the surge voltage to ground, thereby protecting subsequent circuits from damage. This step-by-step conduction feature avoids residual voltage superposition, significantly reducing the residual voltage and absorbing more surge energy, thus improving the circuit's protection capability. Unlike the first implementation method, this trigger circuit uses a three-gas discharge tube structure. The sum of the DC breakdown voltages of the three selected gas discharge tubes is approximately equal to the sum of the DC breakdown voltages of the two gas discharge tubes in the first implementation method. Thus, the third implementation method can achieve the same withstand voltage effect as the scheme in the first implementation method. At the same time, since the higher the DC breakdown voltage of the gas discharge tube, the higher its pulse breakdown voltage, the trigger circuit composed of three gas discharge tubes with lower DC breakdown voltages will have a lower residual voltage from each gas discharge tube. Combined with the step-by-step conduction method, it can achieve a lower residual voltage effect than the first implementation method, resulting in better circuit protection.

[0037] As a fourth implementation method, see attached Figure 7 The diagram shows an improvement upon the third implementation method. Specifically, the trigger circuit consists of gas discharge tubes G1, G2, and G3, resistors R1, R2, and R3, and two RC branches. One RC branch comprises capacitor C1 and resistor R4 connected in parallel across gas discharge tubes G2 and G3, while the other RC branch comprises capacitor C2 and resistor R5 connected in parallel across gas discharge tube G3. Furthermore, resistor R1 is connected in parallel across gas discharge tube G1, resistor R2 is connected in parallel across gas discharge tubes G2 and G3, and resistor R3 is connected in parallel across gas discharge tube G2. Gas discharge tubes G1, G2, and G3 are of the same model. Resistor R2 has twice the resistance of resistor R1. Capacitors C1 and C2 are pF level capacitors, with capacitor C2 being larger than capacitor C1. Resistors R4 and R5 are much smaller than resistors R1, R2, and R3, and resistors R1 and R2 are much smaller than resistor R3.

[0038] Under normal operating voltage, gas discharge tubes G1, G2, and G3 maintain a high impedance or open circuit state, are non-conductive, and allow current to flow through resistors R1 and R2. During the withstand voltage test, gas discharge tubes G1, G2, and G3 achieve equal voltage division, and can achieve a certain proportion of voltage division with the varistor MOV, thereby improving the circuit's withstand voltage capability. When a transient surge voltage appears in the input voltage signal, gas discharge tube G1 turns on first, followed by gas discharge tube G2, then gas discharge tube G3, and finally the varistor MOV turns on (as shown in the attached diagram). Figure 8As shown, the surge current is discharged, guiding the surge voltage to ground, thereby protecting subsequent circuits from damage. This step-by-step conduction characteristic avoids residual voltage superposition, significantly reducing the residual voltage and absorbing more surge energy, thus improving the circuit's protection capability. Unlike the third implementation method, this trigger circuit can generate a larger voltage difference between gas discharge tubes G2 and G3 when facing surge voltage, thereby further reducing the residual voltage superposition between gas discharge tubes G2 and G3 and further reducing the overall residual voltage.

[0039] A surge protector includes the aforementioned trigger circuit.

[0040] The key design feature of this invention lies in its overvoltage protection module and RC branch forming a trigger circuit. This circuit utilizes the voltage division effect of resistors and capacitors to effectively reduce the residual voltage after the gas discharge tube is turned on, protecting subsequent circuitry. The gas discharge tube and RC branch enhance the circuit's tolerance to transient high voltages, achieving higher withstand voltage. Simultaneously, the gas discharge tube provides protection against transient high voltages, improving circuit reliability. Furthermore, the circuit uses inexpensive components and supports both surface-mount and through-hole packages, offering designers flexibility and facilitating wide application in various fields such as communications, power supplies, and signal processing, providing stable and effective signal protection.

[0041] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A trigger circuit, characterized in that: The device includes an overvoltage protection module and an RC branch. The overvoltage protection module includes at least two switching devices and at least two impedance branches. The two ends of the two switching devices connected in series are electrically connected to the first and second ends of the trigger circuit, respectively. The two impedance branches are connected in parallel with the two switching devices in a one-to-one correspondence, or one impedance branch is connected in parallel with one of the switching devices, and the other impedance branch is connected in parallel across the two switching devices. The RC branch is connected in parallel across one of the switching devices and / or in parallel across both switching devices.

2. The trigger circuit according to claim 1, characterized in that: It also includes a varistor, which is connected in series between the first terminal of the trigger circuit and the two switching devices. The RC branch includes a resistor and a capacitor connected in series, and the RC branch is connected in parallel across one of the switching devices.

3. The trigger circuit according to claim 1, characterized in that: It also includes a varistor, which is connected in series between the first terminal of the trigger circuit and the two switching devices. The RC branch includes a resistor and a capacitor connected in series, and the RC branch is connected in parallel across one of the switching devices. One impedance branch is connected in parallel with one of the switching devices, and the other impedance branch is connected in parallel across both switching devices.

4. The trigger circuit according to claim 1, characterized in that: It includes three switching devices and three impedance branches, with each impedance branch connected in parallel to one of the three switching devices. The RC branch includes two sets of resistors and capacitors connected in series, one set of which is connected in parallel to one of the switching devices; the other set of which is connected in parallel to the two switching devices. It also includes a varistor connected in series between the first terminal of the trigger circuit and the three switching devices.

5. The trigger circuit according to claim 1, characterized in that: It includes three switching devices and three impedance branches, two of which are connected in parallel with two switching devices in a one-to-one correspondence; the other impedance branch is connected in parallel with the two ends of the two switching devices; the RC branch includes two sets of resistors and capacitors connected in series, one set of which is connected in parallel with the two ends of one of the switching devices; the other set of which is connected in parallel with the two ends of the two switching devices; it also includes a varistor, which is connected in series between the first terminal of the trigger circuit and the three switching devices.

6. The trigger circuit according to claim 1, characterized in that: The switching device is a gas discharge tube and / or a semiconductor discharge tube, and all switching devices have the same model number.

7. The trigger circuit according to claim 1, characterized in that: The RC branch includes resistors and capacitors connected in series.

8. The trigger circuit according to claim 7, characterized in that: The capacitors in the RC branch are pF level capacitors.

9. The trigger circuit according to claim 4, characterized in that: The impedance branches are resistors, and the resistance values ​​of each impedance branch are the same.

10. A surge protector, characterized in that: It includes the trigger circuit as described in any one of claims 1-9.

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