Overvoltage protection circuit and overvoltage protection system

Abstract

This application relates to the field of surge protection technology and provides an overvoltage protection circuit and an overvoltage protection system. The overvoltage protection circuit includes a first overcurrent protection unit, a second overcurrent protection unit, a first overvoltage protection unit, and a second overvoltage protection unit. The first overcurrent protection unit is electrically connected to the first terminal of the first overvoltage protection unit, and the second overcurrent protection unit is electrically connected to the first terminal of the second overvoltage protection unit. The second terminals of both the first and second overvoltage protection units are grounded. The first terminals of both the first and second overvoltage protection units are used for electrical connection to downstream circuitry. In summary, the overvoltage protection circuit of this application significantly improves surge protection levels compared to traditional solutions, meeting the increasing demands for circuit safety protection.

Description

Technical Field

[0001] This application belongs to the field of surge protection technology, and in particular relates to an overvoltage protection circuit and an overvoltage protection system. Background Technology

[0002] In the telecommunications field, telephone lines between telecommunications bureaus and users' homes are typically several kilometers long, making them highly susceptible to high-voltage interference such as lightning strikes, power line contact, and power line induction during transmission. If these high-voltage currents enter the SLIC (Subscriber Line Interface Circuit) chip, they can easily cause the chip to break down or burn out. Therefore, to ensure the normal operation of the SLIC chip, an overvoltage protection circuit must be added at its front end. Currently, the commonly used devices in traditional SLIC overvoltage protection circuits are programmable voltage protection devices, such as Bourns' TISP61089B. However, due to its limited lightning protection capability, using this device for surge protection results in a low surge protection level, which is insufficient to meet the ever-increasing demands for circuit safety protection. Utility Model Content

[0003] This application provides an overvoltage protection circuit and an overvoltage protection system, which can solve the problem that existing surge protection solutions have low surge protection levels and are difficult to meet the growing demand for circuit safety protection.

[0004] In a first aspect, embodiments of this application provide an overvoltage protection circuit applied to an SLIC circuit.

[0005] The surge protection circuit includes a first overcurrent protection unit, a second overcurrent protection unit, a first overvoltage protection unit, and a second overvoltage protection unit. The first overcurrent protection unit is electrically connected to the first terminal of the first overvoltage protection unit, and the second overcurrent protection unit is electrically connected to the first terminal of the second overvoltage protection unit. The second terminals of both the first and second overvoltage protection units are grounded. The first terminals of both the first and second overvoltage protection units are used to be electrically connected to the back-end circuit on the SLIC line.

[0006] The first overcurrent protection unit is used to limit the current on the first transmission line in the SLIC line to be less than a first current, the second overcurrent protection unit is used to limit the current on the second transmission line in the SLIC line to be less than a second current, the first overvoltage protection unit is used to transfer the first surge energy on the first transmission line to ground, the second overvoltage protection unit is used to transfer the second surge energy on the second transmission line to ground, and both the first overvoltage protection unit and the second overvoltage protection unit include a TSS (Thyristor Surge Protector) device.

[0007] In one possible implementation of the first aspect, the first overvoltage protection unit includes a first TSS tube, the first end of the first TSS tube serving as the first end of the first overvoltage protection unit and electrically connected to the first overcurrent protection unit for electrical connection with the back-end circuit, and the second end of the first TSS tube serving as the second end of the first overvoltage protection unit and grounded.

[0008] In one possible implementation of the first aspect, the second overvoltage protection unit includes a second TSS tube, the first end of the second TSS tube serving as the first end of the second overvoltage protection unit and electrically connected to the second overcurrent protection unit for electrical connection with the back-end circuit, and the second end of the second TSS tube serving as the second end of the second overvoltage protection unit grounded.

[0009] In one possible implementation of the first aspect, the first overcurrent protection unit includes a first protection resistor connected in series with the first transmission line.

[0010] In one possible implementation of the first aspect, the first protective resistor is a thermistor.

[0011] In one possible implementation of the first aspect, the second overcurrent protection unit includes a second protection resistor connected in series with the second transmission line.

[0012] In one possible implementation of the first aspect, the second protective resistor is a thermistor.

[0013] Secondly, embodiments of this application provide an overvoltage protection system, including a back-end circuit and an overvoltage protection circuit as described in any one of the first aspects, wherein the back-end circuit is electrically connected to a first overcurrent protection unit, a second overcurrent protection unit, a first terminal of the first overvoltage protection unit, and a first terminal of the second overvoltage protection unit in the overvoltage protection circuit.

[0014] In one possible implementation of the second aspect, the back-end circuit includes a first resistor unit, a second resistor unit, a rectifier unit, and an SLIC chip. The first resistor unit is electrically connected to a first terminal of the first overcurrent protection unit, the first overvoltage protection unit, the rectifier unit, and the SLIC chip, respectively. The second resistor unit is electrically connected to a second terminal of the second overcurrent protection unit, the second overvoltage protection unit, the rectifier unit, and the SLIC chip, respectively.

[0015] In one possible implementation of the second aspect, the rectifier unit includes a first diode, a second diode, a third diode, and a fourth diode. The anode of the first diode is electrically connected to the cathode of the second diode, the first resistor unit, and a first terminal of the SLIC chip, respectively. The cathode of the first diode is electrically connected to the cathode of the fourth diode. The anode of the third diode is electrically connected to the anode of the second diode. The cathode of the third diode is electrically connected to the anode of the fourth diode, the second resistor unit, and a second terminal of the SLIC chip, respectively.

[0016] Alternatively, the rectifier unit includes a fifth diode and a sixth diode, with the anodes of the fifth diode and the sixth diode electrically connected, the cathodes of the fifth diode electrically connected to the first resistor unit and the first terminal of the SLIC chip, and the cathodes of the sixth diode electrically connected to the second resistor unit and the second terminal of the SLIC chip.

[0017] The beneficial effects of the embodiments in this application compared with the prior art are:

[0018] The overvoltage protection circuit provided in this application includes a first overcurrent protection unit, a second overcurrent protection unit, a first overvoltage protection unit, and a second overvoltage protection unit. The first and second overcurrent protection units limit the current on the SLIC line, thereby providing overcurrent protection for the downstream circuit. Both the first and second overvoltage protection units include TSS devices. Since TSS devices possess the capability to achieve high surge protection levels when facing surge energy, they provide overvoltage protection for the downstream circuit. When a common-mode positive overvoltage occurs, the TSS device conducts forward, diverting the surge energy to ground; when a common-mode negative overvoltage occurs, the TSS device breaks down and conducts in reverse, diverting the surge energy to ground, thus achieving the conduction and release of surge energy and providing overvoltage protection. Because both overvoltage protection units contain TSS devices with high lightning strike resistance, the entire overvoltage protection circuit can achieve a high surge protection level by leveraging the characteristics of the TSS devices when dealing with surge situations. In summary, the overvoltage protection circuit of this application embodiment has a significantly improved surge protection level compared with the traditional solution, which can meet the growing demand for circuit safety protection. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the principle analysis of existing surge protection schemes;

[0021] Figure 2 This is a schematic diagram illustrating another principle of existing surge protection schemes;

[0022] Figure 3 This is a schematic block diagram of an overvoltage protection circuit provided in one embodiment of this application;

[0023] Figure 4 This is a schematic diagram illustrating the principle of an overvoltage protection circuit provided in one embodiment of this application;

[0024] Figure 5 This is a schematic diagram illustrating the principle of an overvoltage protection circuit provided in another embodiment of this application;

[0025] Figure 6 This is a circuit connection diagram of an overvoltage protection system provided in an embodiment of this application;

[0026] Figure 7 This is a circuit connection diagram of an overvoltage protection system provided in another embodiment of this application;

[0027] Figure 8 This is surge test data of an overvoltage protection system provided in one embodiment of this application.

[0028] In the diagram, 10 is the overvoltage protection circuit; 101 is the first overcurrent protection unit; 102 is the second overcurrent protection unit; 103 is the first overvoltage protection unit; 104 is the second overvoltage protection unit; 20 is the back-end circuit; 201 is the first resistor unit; 202 is the second resistor unit; and 203 is the rectifier unit. Detailed Implementation

[0029] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0030] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0031] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0033] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0035] In the telecommunications field, telephone lines between telecommunications bureaus and users' homes are typically several kilometers long, making them highly susceptible to high-voltage interference during transmission, such as lightning strikes, power line contact, and power line induction. If these high-voltage currents enter the SLIC chip, they can potentially cause the chip to break down or burn out. Therefore, to ensure the normal operation of the SLIC chip, an overvoltage protection circuit must be added at its front end. For example... Figure 1 and Figure 2As shown, the commonly used devices in traditional SLIC overvoltage protection circuits are programmable voltage protection devices, such as Bourns' TISP61089B. When a common-mode positive overvoltage occurs, it is introduced to PE (Protective Earthing) via a diode connected in reverse parallel with the thyristor; when a common-mode negative overvoltage occurs, it is introduced to PE via a thyristor. However, due to the limited lightning protection capability of the TISP61089B, surge protection using this device is relatively low, reaching only 2KV@10 / 700μs, which is insufficient to meet the increasing demands for circuit safety protection. Furthermore, the TISP61089B is relatively expensive, thus increasing the overall cost of surge protection circuits.

[0036] Based on the above problems, the overvoltage protection circuit provided in this application includes a first overcurrent protection unit, a second overcurrent protection unit, a first overvoltage protection unit, and a second overvoltage protection unit. The first and second overcurrent protection units limit the current on the SLIC line, thereby achieving overcurrent protection for the downstream circuit. Both the first and second overvoltage protection units include TSS devices. Since TSS devices have the capability to achieve high surge protection levels when facing surge energy, they achieve overvoltage protection for the downstream circuit. When a common-mode positive overvoltage occurs, the TSS device conducts forward, diverting the surge energy to ground; when a common-mode negative overvoltage occurs, the TSS device breaks down and conducts in reverse, diverting the surge energy to ground, thus achieving the conduction and release of surge energy and providing overvoltage protection. Because both overvoltage protection units contain TSS devices with high lightning strike resistance, the entire overvoltage protection circuit can achieve a high surge protection level when dealing with surge situations, thanks to the characteristics of the TSS devices. In summary, the overvoltage protection circuit of this application embodiment has a significantly improved surge protection level compared with the traditional solution, which can meet the growing demand for circuit safety protection.

[0037] To illustrate the technical solution described in this application, specific embodiments are provided below.

[0038] Figure 3 A schematic block diagram of an overvoltage protection circuit 10 according to an embodiment of this application is shown. See also... Figure 3As shown, the overvoltage protection circuit 10 is applied to the SLIC line. The overvoltage protection circuit 10 includes a first overcurrent protection unit 101, a second overcurrent protection unit 102, a first overvoltage protection unit 103, and a second overvoltage protection unit 104. The first overcurrent protection unit 101 is electrically connected to the first end of the first overvoltage protection unit 103, and the second overcurrent protection unit 102 is electrically connected to the first end of the second overvoltage protection unit 104. The second ends of the first overvoltage protection unit 103 and the second overvoltage protection unit 104 are both grounded. The first ends of the first overvoltage protection unit 103 and the first ends of the second overvoltage protection unit 104 are both used to be electrically connected to the back-end circuit 20 on the SLIC line.

[0039] Specifically, the first overcurrent protection unit 101 and the second overcurrent protection unit 102 limit the current on the SLIC line, thereby achieving overcurrent protection for the downstream circuit 20. The first overvoltage protection unit 103 and the second overvoltage protection unit 104 both include TSS devices. Since TSS devices possess the capability to achieve high surge protection levels when facing surge energy, they also provide overvoltage protection for the downstream circuit 20. When a common-mode positive overvoltage occurs, the TSS device conducts forward, diverting the surge energy to ground; when a common-mode negative overvoltage occurs, the TSS device breaks down and conducts in reverse, diverting the surge energy to ground, thus achieving the conduction and release of surge energy and providing overvoltage protection. Because both overvoltage protection units contain TSS devices with high lightning strike resistance, the entire overvoltage protection circuit 10 can achieve a high surge protection level by leveraging the characteristics of the TSS devices when dealing with surge situations. In summary, the overvoltage protection circuit 10 of this embodiment significantly improves the surge protection level compared to traditional solutions, meeting the ever-increasing demands for circuit safety protection.

[0040] It should be noted that the second terminal of the first overvoltage protection unit 103 and the second terminal of the second overvoltage protection unit 104 are both grounded, which indicates that the second terminals of the first overvoltage protection unit 103 and the second terminals of the second overvoltage protection unit 104 are both connected to the earth, introducing surge energy into the earth. It also indicates that the second terminals of the first overvoltage protection unit 103 and the second terminals of the second overvoltage protection unit 104 are both connected to the chassis ground, introducing surge energy into the chassis ground.

[0041] It should be noted that, compared to traditional surge protection circuits, both the first overvoltage protection unit 103 and the second overvoltage protection unit 104 in this application employ TSS devices. TSS devices are manufactured using semiconductor processes, featuring high integration, good consistency, and low cost during mass production. TSS devices have extremely fast response speeds, with nanosecond-level response times enabling them to quickly clamp overvoltages within a safe range, eliminating the need for numerous auxiliary components, simplifying circuit design, and reducing printed circuit board area and assembly costs. Furthermore, TSS devices possess excellent surge resistance and a long service life, reducing subsequent maintenance and replacement costs. Therefore, compared to traditional surge protection circuits, the TSS device solution in this application achieves a significant cost reduction while maintaining protection performance, resulting in higher cost-effectiveness and market competitiveness.

[0042] It should be noted that, Figure 3 In a SLIC (Signal Communication Interface) telephone line, the TIP and RING lines are signal transmission lines. The TIP line primarily transmits a portion of the voice or data signal. In analog telephone lines, the TIP line typically carries one polarity component of the voice signal. The RING and TIP lines together form a complete signal transmission loop. In telephone systems, the RING line is often associated with the ringing signal. When a call comes in, a specific voltage signal is applied to the RING line to drive the telephone to ring. Simultaneously, it also participates in the transmission of the other polarity component of the voice or data signal, working in conjunction with the TIP line to achieve complete communication functionality. When a positive overvoltage occurs, it is introduced by the TIP and RING lines.

[0043] In one embodiment of this application, such as Figure 4 or Figure 5 As shown, the first overvoltage protection unit 103 includes a first TSS tube TSS1. The first end of the first TSS tube TSS1 serves as the first end of the first overvoltage protection unit 103 and is electrically connected to the first overcurrent protection unit 101 for electrical connection with the back-end circuit 20. The second end of the first TSS tube TSS1 serves as the second end of the first overvoltage protection unit 103 and is grounded.

[0044] Specifically, the first TSS transistor, TSS1, serves as the core component of the first overvoltage protection unit 103. Connected between the first transmission line and ground, it suppresses common-mode surge voltage damage to the downstream circuit 20. When a common-mode positive overvoltage occurs on the first transmission line, the first TSS transistor, TSS1, conducts in the forward direction. When a common-mode negative overvoltage occurs, the first TSS transistor, TSS1, conducts in the reverse direction after breakdown. Regardless of the polarity of the overvoltage, the first TSS transistor, TSS1, can quickly discharge the surge energy to the PE through a low-impedance path, thereby clamping the line voltage to a safe range and achieving overvoltage protection for the downstream circuit 20. Furthermore, the bidirectional conduction characteristic of the first TSS transistor, TSS1, ensures that both positive and negative polarity surges can be effectively absorbed and released, improving the system's anti-interference capability and reliability.

[0045] In one embodiment of this application, such as Figure 4 or Figure 5 As shown, the second overvoltage protection unit 104 includes a second TSS tube TSS2. The first end of the second TSS tube TSS2 serves as the first end of the second overvoltage protection unit 104 and is electrically connected to the second overcurrent protection unit 102 for electrical connection with the back-end circuit 20. The second end of the second TSS tube TSS2 serves as the second end of the second overvoltage protection unit 104 and is grounded.

[0046] Specifically, the second TSS transistor, TSS2, serves as the core component of the second overvoltage protection unit 104. Connected between the second transmission line and ground, it suppresses common-mode surge voltage damage to the downstream circuit 20. When a common-mode positive overvoltage occurs on the second transmission line, the second TSS transistor, TSS2, conducts in the forward direction. When a common-mode negative overvoltage occurs, the second TSS transistor, TSS2, conducts in the reverse direction after breakdown. Regardless of the polarity of the overvoltage, the second TSS transistor, TSS2, can quickly discharge the surge energy to the PE through a low-impedance path, thereby clamping the line voltage to a safe range and achieving overvoltage protection for the downstream circuit 20. Furthermore, the bidirectional conduction characteristic of the second TSS transistor, TSS2, ensures that both positive and negative polarity surges can be effectively absorbed and released, improving the system's anti-interference capability and reliability.

[0047] It should be noted that, Figure 4 and Figure 5 The dashed line with an arrow indicates the transmission path of surge energy.

[0048] In one embodiment of this application, such as Figure 4 or Figure 5 As shown, the first overcurrent protection unit 101 includes a first protection resistor RPTC1, which is connected in series on the first transmission line. The first end of the first protection resistor RPTC1 is used to connect to the TIP interface, and the second end of the first protection resistor RPTC1 is electrically connected to the first end of the first TSS tube TSS1 and the back-end circuit 20, respectively.

[0049] Specifically, the first protection resistor RPTC1, as an inherent protection device, can limit the current on the first transmission line to be less than a first current, which can be a pre-set current. When an abnormal situation occurs in the circuit, such as a short circuit or a sudden increase in current, the first protection resistor RPTC1 will limit the magnitude of the current to prevent excessive current from damaging the downstream circuit 20, ensuring that the downstream circuit 20 operates within a safe current range, thereby guaranteeing the stability and reliability of the entire circuit system.

[0050] It should be noted that the first protection resistor RPTC1 can be a PTC (Positive Temperature Coefficient) thermistor. Because thermistors have a positive temperature coefficient, their resistance increases rapidly with increasing temperature. When an overcurrent occurs on the first transmission line, the heat generated by the current flowing through the thermistor raises its temperature, causing a rapid increase in resistance and thus limiting the current. Once the fault is cleared, the thermistor's temperature drops, and its resistance returns to its initial lower value. The circuit can automatically resume normal operation without manual resistor replacement, improving the circuit's ease of use and maintainability. Furthermore, thermistors respond quickly to current changes. Once the current exceeds the normal range, the thermistor can quickly sense the temperature change and increase its resistance, providing timely protection for the circuit and preventing damage to downstream circuits from prolonged exposure to excessive current.

[0051] For example, the designer can select the resistance value of the first protection resistor RPTC1 according to the actual situation. For example, the resistance value of the first protection resistor RPTC1 can be selected as 55Ω.

[0052] In one embodiment of this application, such as Figure 4 or Figure 5 As shown, the second overcurrent protection unit 102 includes a second protection resistor RPTC2, which is connected in series on the second transmission line. The first end of the second protection resistor RPTC2 is used to connect to the RING interface, and the second end of the second protection resistor RPTC2 is electrically connected to the first end of the second TSS tube TSS2 and the back-end circuit 20, respectively.

[0053] Specifically, the second protection resistor RPTC2, as an inherent protection device, limits the current on the second transmission line to a lower value than a pre-set current. When an abnormal situation occurs in the circuit, such as a short circuit or a sudden increase in current, the second protection resistor RPTC2 limits the current magnitude to prevent excessive current from damaging the downstream circuit 20, ensuring that the downstream circuit 20 operates within a safe current range, thereby guaranteeing the stability and reliability of the entire circuit system.

[0054] It should be noted that the second protection resistor RPTC2 can be a PTC thermistor. Because thermistors have a positive temperature coefficient, their resistance increases rapidly with increasing temperature. When an overcurrent occurs on the second transmission line, the heat generated by the current flowing through the thermistor raises its temperature, causing a rapid increase in resistance and thus limiting the current. Once the fault is cleared, the thermistor's temperature drops, and its resistance returns to its initial lower value. The circuit can automatically resume normal operation without manual resistor replacement, improving the circuit's ease of use and maintainability. Furthermore, thermistors respond quickly to current changes. Once the current exceeds the normal range, the thermistor can quickly sense the temperature change and increase its resistance, providing timely protection and preventing damage to downstream circuits from prolonged exposure to excessive current.

[0055] For example, the designer can select the resistance value of the second protection resistor RPTC2 according to the actual situation. For example, the resistance value of the second protection resistor RPTC2 can be selected as 55Ω.

[0056] It should be noted that other numbers of the first protection resistor RPTC1 and the second protection resistor RPTC2 can be connected in series and parallel to limit the current transmitted to the back-end circuit 20, which is not limited here.

[0057] It should be noted that this application uses two protective resistors and two TSS devices with high lightning strike resistance to form the overvoltage protection circuit 10. This allows the entire surge protection circuit 10 to achieve a surge protection level of 4KV@10 / 700μs in the event of a surge, thanks to the characteristics of the TSS devices. Compared to traditional solutions, this represents a significant improvement in surge protection level and can meet the growing demand for circuit safety protection.

[0058] This application also discloses an overvoltage protection system, including a back-end circuit 20 and the aforementioned overvoltage protection circuit 10. The back-end circuit 20 is electrically connected to the first terminals of the first overcurrent protection unit 101, the second overcurrent protection unit 102, the first overvoltage protection unit 103, and the second overvoltage protection unit 104 in the overvoltage protection circuit 10. By employing the aforementioned overvoltage protection circuit 10, the overvoltage protection system ensures that the back-end circuit 20 receives comprehensive and effective protection in the face of various complex surge conditions. When an overcurrent occurs in the circuit, the protective resistors, such as PTC resistors, in the first overcurrent protection unit 101 and the second overcurrent protection unit 102 will automatically adjust their resistance values ​​according to the current magnitude, limiting the abnormal increase in current and preventing excessive current from causing irreversible damage to the electronic components in the downstream circuit 20. Conversely, in the event of an overvoltage, the TSS devices in the first overvoltage protection unit 103 and the second overvoltage protection unit 104 can respond quickly, promptly diverting the overvoltage surge energy to ground, regardless of whether it is a common-mode positive overvoltage or a common-mode negative overvoltage, ensuring that the voltage across the downstream circuit 20 remains within a safe threshold range. Through this dual overcurrent and overvoltage protection mechanism, the overvoltage protection system not only significantly improves the stability and reliability of the downstream circuit 20 and extends the service life of the downstream circuit 20 and related equipment, but also reduces equipment failures and maintenance costs caused by surge impacts.

[0059] In one embodiment of this application, such as Figure 6 or Figure 7 As shown, the back-end circuit 20 includes a first resistor unit 201, a second resistor unit 202, a rectifier unit 203, and an SLIC chip. The first resistor unit 201 is electrically connected to the first terminals of the first overcurrent protection unit 101, the first overvoltage protection unit 103, the rectifier unit 203, and the SLIC chip, respectively. The second resistor unit 202 is electrically connected to the second terminals of the second overcurrent protection unit 102, the second overvoltage protection unit 104, the rectifier unit 203, and the SLIC chip, respectively.

[0060] Specifically, both the first resistor unit 201 and the second resistor unit 202 are used to limit the current transmitted to the SLIC chip. When an abnormal overcurrent occurs in the circuit, the resistor unit will impede the current increase, preventing excessive current from flowing into the SLIC chip, thus providing initial overcurrent protection. The rectifier unit 203 is used to convert the AC signal into a DC signal, ensuring that the downstream SLIC chip receives a relatively stable DC signal and guaranteeing normal chip operation.

[0061] In one embodiment of this application, such as Figure 6 or Figure 7As shown, the first resistor unit 201 includes a first resistor R1. The first end of the first resistor R1 is electrically connected to the first overcurrent protection unit 101 and the first overvoltage protection unit 103, respectively, and the second end of the first resistor R1 is electrically connected to the first end of the SLIC chip.

[0062] Specifically, the first resistor R1 is used to limit the current transmitted to the first terminal of the SLIC chip to prevent excessive current from damaging the chip.

[0063] For example, the designer can select the resistance value of the first resistor R1 according to the actual situation. For example, the resistance value of the first resistor R1 can be selected as 20Ω.

[0064] In one embodiment of this application, such as Figure 6 or Figure 7 As shown, the second resistor unit 202 includes a second resistor R2. The first end of the second resistor R2 is electrically connected to the second overcurrent protection unit 102 and the second overvoltage protection unit 104, respectively. The second end of the second resistor R2 is electrically connected to the second end of the SLIC chip.

[0065] Specifically, the second resistor R2 is used to limit the current transmitted to the second terminal of the SLIC chip to prevent excessive current from damaging the chip.

[0066] For example, the designer can select the resistance value of the second resistor R2 according to the actual situation. For example, the resistance value of the second resistor R2 can be selected as 20Ω.

[0067] In one embodiment of this application, such as Figure 6 As shown, the rectifier unit 203 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anode of the first diode D1 is electrically connected to the cathode of the second diode D2, the first resistor unit 201, and the first terminal of the SLIC chip. The cathode of the first diode D1 is electrically connected to the cathode of the fourth diode D4. The anode of the third diode D3 is electrically connected to the anode of the second diode D2. The cathode of the third diode D3 is electrically connected to the anode of the fourth diode D4, the second resistor unit 202, and the second terminal of the SLIC chip.

[0068] Specifically, the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 form a full-bridge rectifier to convert the AC signal into a DC signal, ensuring that the SLIC chip at the back end receives a relatively stable DC signal and that the chip works normally.

[0069] In one embodiment of this application, such as Figure 7As shown, the rectifier unit 203 includes a fifth diode D5 and a sixth diode D6. The anodes of the fifth diode D5 and the sixth diode D6 are electrically connected. The cathodes of the fifth diode D5 are electrically connected to the first resistor unit 201 and the first terminal of the SLIC chip, respectively. The cathodes of the sixth diode D6 are electrically connected to the second resistor unit 202 and the second terminal of the SLIC chip, respectively.

[0070] Specifically, diodes D5 (fifth) and D6 (sixth) form a half-bridge rectifier. Compared to a full-bridge rectifier, the half-bridge rectifier reduces the number of diodes used, effectively controlling production costs. Furthermore, in a half-bridge rectifier circuit, current flows through only one diode, resulting in lower power loss across the diode compared to a full-bridge rectifier.

[0071] It should be noted that, as Figure 6 or Figure 7 As shown, the back-end circuit 20 also includes a first capacitor C1 and a second capacitor C2. The first terminal of the first capacitor C1 is connected to the first terminal of the SLIC chip, and the first terminal of the second capacitor C2 is connected to the second terminal of the SLIC chip. The second terminals of both the first capacitor C1 and the second capacitor C2 are grounded. The first capacitor C1 and the second capacitor C2 are used to filter the voltage transmitted to the SLIC chip to prevent high-frequency noise signals from interfering with the chip. The capacitance values ​​of both the first capacitor C1 and the second capacitor C2 can be selected as 15nF.

[0072] It should be noted that this application tests the residual voltage of individual TSS devices according to the IEC61000-4-5 outdoor signal line routing test standard of 4KV@10 / 700μs. Figure 8 The data for the residual voltage test of 5 PCS samples shows that the test can meet the requirements of 4KV@10 / 700μs. The average forward residual voltage is around 120V and the reverse residual voltage is around 145V. The overall residual voltage test performance is better than that of the traditional TISP61089B.

[0073] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An overvoltage protection circuit, characterized in that, Applied to SLIC lines, the overvoltage protection circuit includes a first overcurrent protection unit, a second overcurrent protection unit, a first overvoltage protection unit, and a second overvoltage protection unit. The first overcurrent protection unit is electrically connected to the first terminal of the first overvoltage protection unit, and the second overcurrent protection unit is electrically connected to the first terminal of the second overvoltage protection unit. The second terminals of both the first and second overvoltage protection units are grounded. The first terminals of both the first and second overvoltage protection units are used to be electrically connected to the back-end circuit on the SLIC line. The first overcurrent protection unit is used to limit the current on the first transmission line of the SLIC line to be less than a first current, the second overcurrent protection unit is used to limit the current on the second transmission line of the SLIC line to be less than a second current, the first overvoltage protection unit is used to transfer the first surge energy on the first transmission line to ground, the second overvoltage protection unit is used to transfer the second surge energy on the second transmission line to ground, and both the first overvoltage protection unit and the second overvoltage protection unit include a TSS device.

2. The overvoltage protection circuit according to claim 1, characterized in that, The first overvoltage protection unit includes a first TSS tube. The first end of the first TSS tube serves as the first end of the first overvoltage protection unit and is electrically connected to the first overcurrent protection unit for electrical connection with the back-end circuit. The second end of the first TSS tube serves as the second end of the first overvoltage protection unit and is grounded.

3. The overvoltage protection circuit according to claim 1, characterized in that, The second overvoltage protection unit includes a second TSS tube. The first end of the second TSS tube serves as the first end of the second overvoltage protection unit and is electrically connected to the second overcurrent protection unit for electrical connection with the back-end circuit. The second end of the second TSS tube serves as the second end of the second overvoltage protection unit and is grounded.

4. The overvoltage protection circuit according to claim 1, characterized in that, The first overcurrent protection unit includes a first protection resistor, which is connected in series with the first transmission line.

5. The overvoltage protection circuit according to claim 4, characterized in that, The first protective resistor is a thermistor.

6. The overvoltage protection circuit according to claim 1, characterized in that, The second overcurrent protection unit includes a second protection resistor, which is connected in series on the second transmission line.

7. The overvoltage protection circuit according to claim 6, characterized in that, The second protective resistor is a thermistor.

8. An overvoltage protection system, characterized in that, It includes a back-end circuit and an overvoltage protection circuit as described in any one of claims 1-7, wherein the back-end circuit is electrically connected to the first overcurrent protection unit, the second overcurrent protection unit, the first terminal of the first overvoltage protection unit, and the first terminal of the second overvoltage protection unit in the overvoltage protection circuit.

9. The overvoltage protection system according to claim 8, characterized in that, The back-end circuit includes a first resistor unit, a second resistor unit, a rectifier unit, and an SLIC chip. The first resistor unit is electrically connected to the first terminal of the first overcurrent protection unit, the first overvoltage protection unit, the rectifier unit, and the SLIC chip, respectively. The second resistor unit is electrically connected to the second terminal of the second overcurrent protection unit, the second overvoltage protection unit, the rectifier unit, and the SLIC chip, respectively.

10. The overvoltage protection system according to claim 9, characterized in that, The rectifier unit includes a first diode, a second diode, a third diode, and a fourth diode. The anode of the first diode is electrically connected to the cathode of the second diode, the first resistor unit, and the first terminal of the SLIC chip. The cathode of the first diode is electrically connected to the cathode of the fourth diode. The anode of the third diode is electrically connected to the anode of the second diode. The cathode of the third diode is electrically connected to the anode of the fourth diode, the second resistor unit, and the second terminal of the SLIC chip. Alternatively, the rectifier unit includes a fifth diode and a sixth diode, with the anodes of the fifth diode and the sixth diode electrically connected, the cathodes of the fifth diode electrically connected to the first resistor unit and the first terminal of the SLIC chip, and the cathodes of the sixth diode electrically connected to the second resistor unit and the second terminal of the SLIC chip.

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