Surge protection circuit, circuit board, electronic device, and combination device

Abstract

The application relates to the technical field of surge protection, and discloses a surge protection circuit, a circuit board, an electronic device and a combined device, wherein the surge protection circuit comprises a digital user port, a network port, a network transformer, a first protection module, a second protection module and a protection module; the network port is connected with a first winding of the network transformer; the first winding of the network transformer has a first center tap; the first center tap is connected with a first common end through the first protection module; a second winding of the network transformer has a second center tap; the second center tap is connected with a second common end; the digital user port is connected with the first common end through the second protection module; and the first common end is connected with the second common end through the protection module. By arranging two common ends, surges are discharged to an independent reference ground, and then the protection module is used to control the flow direction of the surges to a digital ground, so that the interference of the surges on internal circuits is effectively inhibited, and the stability and reliability of the system are enhanced.

Description

Technical Field

[0001] This application relates to the field of surge protection technology, and in particular to a surge protection circuit, circuit board, electronic device and combination device. Background Technology

[0002] In electronic system design, surge current discharge is a critical aspect of circuit protection design. With the widespread adoption of hybrid digital and analog circuit architectures in modern electronic devices, the digital ground (DGND), serving as the reference plane for digital signals, has a decisive impact on system signal integrity due to its potential stability. Traditional surge protection schemes typically employ transient suppression devices such as gas discharge tubes and varistors to form a discharge loop, directly connecting these devices to the digital ground network to achieve rapid discharge of transient overvoltage energy. However, as the return path for high-speed digital signals, the impedance characteristics of the digital ground network exhibit significant coupling effects with the high-frequency components of the surge current. When a large-current transient pulse is injected into the digital ground plane, a significant local potential difference is generated, leading to fluctuations in the reference level. This ground bounce phenomenon not only interferes with the normal operation of nearby sensitive circuits but also negatively impacts the transmission quality of high-speed signals through common-mode coupling paths. Utility Model Content

[0003] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and provide a surge protection circuit, circuit board, electronic device and combined device.

[0004] In a first aspect, embodiments of this application provide a surge protection circuit, including: a digital user port, a network port, a network transformer, a first protection module, a second protection module, and a protection module; The network port is connected to the first winding of the network transformer, and the first winding of the network transformer has a first center tap, which is connected to a first common terminal through the first protection module. The second winding of the network transformer has a second center tap, which is electrically connected to a second common terminal. The digital user port is connected to the first public terminal through the second protection module, and the first public terminal is connected to the second public terminal through the protection module.

[0005] In some embodiments, the surge protection circuit further includes a power port and a third protection module, wherein the power port is connected to the first common terminal through the third protection module.

[0006] In some embodiments, the first protection module includes a first gas discharge tube, one end of which is connected to the first center tap, and the other end of which is connected to the first common terminal. The second protection module includes a bipolar gas discharge tube, one end of which and the other end of which are electrically connected to the digital user port, and the common ground terminal of which is connected to the first common terminal.

[0007] In some embodiments, the third protection module includes a transient voltage suppressor, one end of which is connected to the positive power terminal of the power supply port, and the other end of which is connected to the first common terminal.

[0008] Secondly, embodiments of this application provide a circuit board, wherein the circuit board is provided with at least one surge protection circuit as described in the first aspect.

[0009] In some embodiments, the circuit board includes a first common terminal, and the ground plane corresponding to the first common terminal is provided with a preset number of layer-swapping vias.

[0010] In some embodiments, the circuit board includes a second common terminal, and the ground plane corresponding to the first common terminal and the ground plane corresponding to the second common terminal are connected at a single point.

[0011] Thirdly, embodiments of this application provide an electronic device, which includes at least one surge protection circuit as described in the first aspect or at least one circuit board as described in the second aspect.

[0012] Fourthly, embodiments of this application provide a combined device, the combined device comprising: a power adapter and at least one electronic device as described in the third aspect above.

[0013] In some embodiments, the power adapter includes an input port and a high-voltage resistor, the input port being connected to the first common terminal via the high-voltage resistor.

[0014] The embodiments of this application have the following beneficial effects: The surge protection circuit of this application includes: a digital user port, a network port, a network transformer, a first protection module, a second protection module, and a protection module. The network port is connected to the first winding of the network transformer, which has a first center tap. The first center tap is connected to a first common terminal through the first protection module. The second winding of the network transformer has a second center tap, which is electrically connected to a second common terminal. The digital user port is connected to the first common terminal through the second protection module, and the first common terminal is connected to the second common terminal through the protection module. The first protection module of this application, by connecting the center tap of the first winding of the network transformer to the first common terminal, can effectively discharge common-mode surge energy from the network port side. The second protection module is set between the digital user port and the first common terminal to suppress surge voltage from the network side, thereby improving the surge current discharge efficiency. Furthermore, by setting two common terminals, the surge is discharged to an independent reference ground, and then controlled by the protection module to flow to the digital ground, effectively suppressing the interference of the surge to the internal circuit and enhancing the stability and reliability of the system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A first structural schematic diagram of a surge protection circuit according to an embodiment of this application is shown; Figure 2 A circuit diagram of the first protection module according to an embodiment of this application is shown; Figure 3 A circuit diagram of the second protection module according to an embodiment of this application is shown; Figure 4 A schematic diagram of the second structure of the surge protection circuit according to an embodiment of this application is shown; Figure 5 A circuit diagram of the third protection module according to an embodiment of this application is shown.

[0017] Explanation of key component symbols: 10: Digital user port; 20: Network port; 30: Network transformer; 40: First protection module; 50: Second protection module; 60: Protection module; 70: Power port; 80: Third protection module. Detailed Implementation The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0018] The components of the embodiments of this application described and illustrated in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] In the following text, the terms "comprising," "having," and their cognates, which may be used in various embodiments of this application, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more combinations thereof. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0020] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. Terms (such as those defined in commonly used dictionaries) shall be interpreted as having the same meaning as in their contextual meaning in the relevant technical field and shall not be construed as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0021] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] Exemplarily, the surge protection circuit of this application is installed in a wired broadband device, which includes a digital user port and a network port. The digital user port is the external access interface for broadband signals, connecting to a telephone line or twisted pair to receive network signals; the network port is used to connect user terminals to build a local area network (LAN). The digital user port transmits network signals to a modem, which demodulates the network signals, extracts digital data frames, and transmits them to a processor. The processor parses the data frames and transmits the data frames that need to be sent to the LAN to an Ethernet chip. The Ethernet chip converts the digital signals into differential analog signals and transmits them to the user terminals through the network port. It also receives data sent by the user terminals and transmits it back to the processor for processing.

[0023] The digital user port and network port are used to connect to external networks or user terminals. These external devices may be at different ground potentials than the wired broadband equipment. In order to prevent the ground potential difference from forming a current loop, a network transformer can be set between the digital user port and the modem, and between the network port and the Ethernet chip. The network transformer is used for physical isolation to protect the wired broadband equipment.

[0024] Since digital user ports and network ports are ports connected to the outside world, they may be subject to the risk of transient surge voltages caused by factors such as lightning strikes, static electricity, and power failures. A network transformer can be used to achieve electrical isolation between the port and the internal circuit, and a surge discharge path can be constructed in conjunction with transient voltage suppression devices such as gas discharge tubes and varistors to guide the surge energy to the grounding network.

[0025] However, in existing technologies, these transient suppression devices are typically directly connected to the digital ground network, i.e., the reference ground plane of digital circuits such as processors and Ethernet chips. While this design can discharge transient overvoltages to some extent, it still has significant shortcomings when facing ultra-high surge protection levels, such as digital user ports and network ports. Specifically: large-current transient pulses injected into the digital ground plane will generate significant local potential differences on the ground plane, thereby interfering with the normal operation of nearby sensitive analog or digital circuits, and even causing system malfunctions or communication interruptions; moreover, if the return path of high-speed signals is interfered with by ground noise, it may cause signal integrity problems; at the same time, common-mode noise propagates through the ground coupling path, causing electromagnetic interference to high-speed differential signal links such as Ethernet, affecting communication quality and stability.

[0026] The first protection module of this application effectively discharges common-mode surge energy from the network port side by connecting the center tap of the first winding of the network transformer to the first common terminal. The second protection module is set between the digital user port and the first common terminal to suppress surge voltage from the network side, thereby improving the surge current discharge efficiency. Furthermore, by setting two common terminals, the surge is discharged to an independent reference ground, and then its flow to the digital ground is controlled by the protection module, which effectively suppresses the interference of the surge to the internal circuit, while meeting the ultra-high surge protection level and enhancing the stability and reliability of the system.

[0027] The surge protection circuit will be described below with reference to some specific embodiments.

[0028] Figure 1 A schematic diagram of a surge protection circuit according to an embodiment of this application is shown. Exemplarily, the surge protection circuit includes a digital user port 10, a network port 20, a network transformer 30, a first protection module 40, a second protection module 50, and a protection module 60.

[0029] In this design, network transformer 30 is denoted by transformer T1. Network port 20 is connected to the first winding of network transformer 30. The first winding of network transformer 30 has a first center tap, which is connected to the first common terminal GND1 via the first protection module 40. The second winding of network transformer 30 has a second center tap, which is connected to the second common terminal GND2. To ensure the normal operation of network transformer 30, as follows... Figure 1 As shown, a capacitor C1 is placed at the second center tap of the network transformer 30, and the second center tap is connected to the second common terminal GND2 through capacitor C1. Exemplarily, network port 20 is a local area network port, the first winding of the network transformer 30 is the primary winding, connected to the user terminal; the second winding is the secondary winding, connected to the Ethernet chip; and the second common terminal GND2 connected to the second center tap is digital ground, i.e., the reference ground plane of digital circuits such as the processor and Ethernet chip.

[0030] Exemplary, such as Figure 2As shown, the first protection module 40 includes a first gas discharge tube GD1. One end of the first gas discharge tube GD1 is connected to a first center tap, and the other end of the first gas discharge tube GD1 is connected to a first common terminal GND1. The specifications of the first gas discharge tube GD1 can be set according to the actual application. For example, network port 20 needs to meet the surge protection level between 10kV and power port 70. To meet the high surge protection requirements of network port 20, the surge test is performed according to the 1.2 / 50μs voltage waveform specified in the surge test standard. The 8 / 20μs short-circuit current waveform is calculated. When the test level is 10kV, the surge test circuit impedance is 10 / 8+2, and the resulting surge current can be estimated by the following formula: 10kV / (10 / 8+2)=3077A. Considering that the gas discharge tube has a current carrying capacity deviation of about 20% in actual applications, to ensure that the device has sufficient safety margin, its rated pulse current should meet: 3077 / 0.8=3846A. In addition, this network port 20 requires a 500DC withstand voltage test. To ensure that the device does not trigger falsely under normal operating voltage, the breakdown voltage of the protection device should not be less than: 500 / 0.8=625V. According to engineering experience, in surge protection design, the energy intensity of the 5 / 320μs waveform is about twice that of the 8 / 20μs waveform. Therefore, to ensure the protective device maintains good withstand capability under a 10kV surge, its rated pulse current under a 5 / 320μs waveform should be no less than 2692A. In summary, the first gas discharge tube GD1 selected for network port 20 must meet the following requirements: breakdown voltage greater than 625V and rated pulse current Ipp ≥ 2692A. This ensures that the device, while meeting the requirements for high-voltage surge impact, possesses sufficient withstand voltage and reliability, effectively guaranteeing the stable operation of the system in harsh electromagnetic environments.

[0031] In this embodiment, the surge discharge path of network port 20 is as follows: the surge voltage is introduced through network port 20, enters the first center tap through the primary winding of network transformer 30, and is guided to the first common terminal GND1 through the first gas discharge tube GD1, separating from the second common terminal GND2. This effectively prevents the surge voltage from damaging critical digital circuits such as Ethernet chips and processors. Simultaneously, electrical isolation is achieved between the primary and secondary windings of network transformer 30 to prevent surge energy from directly entering the equipment, ensuring the safety of equipment and personnel.

[0032] It is understood that this application only uses a single network port 20 as an example for illustration. In practical applications, if the device contains multiple network ports 20, multiple corresponding network transformers 30 and gas discharge tubes can also be set up. Each port is independent of the others and has the same surge suppression capability and circuit structure to ensure that the multi-port device as a whole meets the high-specification surge protection requirements.

[0033] Digital subscriber port 10 is connected to the first common terminal GND1 via the second protection module 50. Exemplarily, digital subscriber port 10 is a digital subscriber line port. The tip and loop of the digital subscriber line port can be connected to the first common terminal GND1 via gas discharge tubes, or via bipolar gas discharge tubes. Exemplarily, such as... Figure 3 As shown, the second protection module 50 includes a bipolar gas discharge tube GD2. One end of the bipolar gas discharge tube GD2 and the other end of the line are electrically connected to the digital user port 10. The common ground terminal of the bipolar gas discharge tube GD2 is connected to the first common terminal GND1. The specifications of the bipolar gas discharge tube GD2 can be set according to the actual application. For example, the digital user port 10 must meet the surge protection level of 13KV between it and the power port 70, and the surge protection level of 7KV between it and the network port 20. In addition, the tip and loop ends of the digital user port 10, as well as the tip and loop ends to the common end, must meet the test requirement of continuous operation for 15 minutes under AC working voltage.

[0034] Specifically, the surge test circuit impedance between digital user port 10 and power port 70 must be 15 + 25 / 2 = 27.5Ω, resulting in a surge current of 473A. Considering the approximately 20% current-carrying capacity deviation of the gas discharge tube in practical applications, to ensure sufficient margin for the device, its rated pulse current should meet the following requirements: 473 / 0.8 = 591A 5 / 320uS. The surge test circuit impedance between network port 20 and digital user port 10 is 10 / 8 + 2, resulting in a surge current of 7kV / (10 / 8 + 2) = 2154A. Again, considering a 20% current-carrying capacity deviation, the rated pulse current of the gas discharge tube should meet the following requirement: 2154 / 0.8 = 2692A 5 / 320uS. To meet the test requirement of continuous operation for 15 minutes at AC operating voltage between the tip and loop terminals of digital user port 10, as well as between the tip and loop terminals and the common terminal, the breakdown voltage of the gas discharge tube should not be less than 230V*1.414 / 0.8=406V. In actual selection, a ceramic gas discharge tube with a nominal breakdown voltage of 420V can be selected to provide additional design margin.

[0035] Furthermore, since digital user port 10 is a high-speed data communication interface, its protection devices must balance surge suppression and signal integrity. Therefore, the junction capacitance of the selected gas discharge tube should be controlled below 10pF to avoid attenuation or distortion of high-frequency communication signals.

[0036] This solution improves the surge protection level between ports by setting a second protection module 50 at the digital user port 10 and using a bipolar gas discharge tube GD2 to achieve common-mode surge protection for the first common terminal GND1, ensuring that the equipment can still operate normally under extreme surge impact.

[0037] The first common terminal GND1 is connected to the second common terminal GND2 through the protection module 60. The protection module 60 can be configured according to the actual application. The protection module 60 can be a ferrite bead or a resistor. By setting the protection module 60 between the first common terminal GND1 and the second common terminal GND2, surge energy is prevented from being coupled to sensitive circuits through the ground plane, thereby improving the electromagnetic compatibility and surge protection capability of the system.

[0038] In one embodiment, based on the above embodiments, Figure 4 A schematic diagram of another surge protection circuit according to an embodiment of this application is shown. The surge protection circuit further includes a power port 70 and a third protection module 80, with the power port 70 connected to the first common terminal GND1 via the third protection module 80. It is understood that the power port 70 is used to connect a power adapter to supply power to the device, exemplary as... Figure 5 As shown, the third protection module 80 includes a transient voltage suppressor D1. One end of the transient voltage suppressor D1 is connected to the positive power terminal of the power port 70, and the other end of the transient voltage suppressor D1 is connected to the first common terminal GND1. By setting the transient voltage suppressor D1 in the power port 70, residual voltage from power adapter surges can be protected, and electrostatic discharge protection can be provided to protect the subsequent circuitry.

[0039] This application embodiment also provides a circuit board, which, exemplary, is provided with the above-mentioned surge protection circuit. Further, the circuit board includes a first common terminal GND1, and the ground plane corresponding to the first common terminal GND1 is provided with a preset number of layer-change vias.

[0040] Specifically, layer-change vias are vias that connect electrical connections between different layers by drilling and electroplating copper. They enable ground connectivity between different layers and can handle large currents or rapidly changing surge currents. The number of layer-change vias for the first common terminal GND1 can be set according to the actual application. For example, the maximum surge current through the circuit is 3846A, and the current carrying capacity of a single 8mil via is approximately 500A. 3846A ÷ 500A / via ≈ 7.7 vias. Considering a 20% margin, a design of 10 vias is reasonable and safe. By setting multiple vias, a low-impedance, short-path ground loop is provided for surge current, dissipating the surge current and reducing local voltage rises on the PCB caused by surge energy, thereby avoiding local burn-out or thermal stress concentration. At the same time, it can reduce the AC impedance of the ground plane between different layers. The low-impedance ground path helps suppress high-frequency noise and improve the system's anti-interference capability.

[0041] The circuit board includes a second common terminal GND2, and the ground plane corresponding to the first common terminal GND1 and the ground plane corresponding to the second common terminal GND2 are connected at a single point. The first common terminal GND1 serves as the reference ground for surge discharge path, used to carry surge current. The second common terminal GND2 is the digital ground for digital circuits such as processors and Ethernet chips. By connecting the ground plane corresponding to the first common terminal GND1 and the ground plane corresponding to the second common terminal GND2 at a single point, the flow path of surge current can be limited, preventing it from flowing into the digital ground. Furthermore, the single-point connection effectively breaks ground loops, improving the system's electromagnetic compatibility.

[0042] Furthermore, setting the spacing between the first common terminal GND1 and the second common terminal GND2 on the same layer of the circuit board to 60 mil or more can meet the basic creepage distance requirements and prevent abnormal discharge. At the same time, it can effectively reduce high-frequency noise coupling and improve signal integrity.

[0043] This application also provides an electronic device, exemplary of which includes the surge protection circuit or the circuit board described above. Exemplarily, the electronic device in this application is a wired broadband device.

[0044] This application also provides a combined device, exemplary of which includes the aforementioned electronic device and power adapter. Specifically, the power adapter is used to supply power to the wired broadband device through power port 70.

[0045] Furthermore, due to safety regulations, traditional surge protection devices such as gas discharge tubes or varistors are not permitted to be used for electrical protection on the high and low voltage sides between the input and output terminals of the power adapter. To meet the testing requirements for 13kV surge voltage, this application employs a high-voltage resistor voltage divider structure as the primary protection method. Multiple megohm-level high-voltage resistors are connected in series to divide the voltage, evenly distributing the surge energy across each resistor, thereby effectively suppressing the impact of surge voltage on subsequent circuits. Specifically, the power adapter includes an input port and high-voltage resistors. The input port is connected to the first common terminal GND1 via high-voltage resistors. The number of high-voltage resistors can be set according to the actual application. For example, four high-voltage resistors are set at the positive terminal of the power adapter's input port and connected to the first common terminal GND1, and four high-voltage resistors are set at the negative terminal of the input port and connected to the first common terminal GND1. For example, high-voltage resistors can be set between the first common terminal GND1 of the power adapter and digital ground for isolation. This allows the power adapter to meet the requirements for a high surge protection level while complying with safety regulations prohibiting the use of nonlinear protection components in the high and low voltage isolation path.

[0046] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that, in alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0047] In addition, the functional modules or units in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0048] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a smartphone, personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0049] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A surge protection circuit, characterized in that, include: Digital user port, network port, network transformer, first protection module, second protection module, and protection module; The network port is connected to the first winding of the network transformer, and the first winding of the network transformer has a first center tap, which is connected to a first common terminal through the first protection module. The second winding of the network transformer has a second center tap, which is electrically connected to a second common terminal. The digital user port is connected to the first public terminal through the second protection module, and the first public terminal is connected to the second public terminal through the protection module.

2. The surge protection circuit according to claim 1, characterized in that, The surge protection circuit also includes a power port and a third protection module, wherein the power port is connected to the first common terminal through the third protection module.

3. The surge protection circuit according to claim 1, characterized in that, The first protection module includes a first gas discharge tube, one end of which is connected to the first center tap, and the other end of which is connected to the first common terminal. The second protection module includes a bipolar gas discharge tube, one end of which and the other end of which are electrically connected to the digital user port, and the common ground terminal of which is connected to the first common terminal.

4. The surge protection circuit according to claim 2, characterized in that, The third protection module includes a transient voltage suppressor, one end of which is connected to the positive terminal of the power supply port, and the other end of which is connected to the first common terminal.

5. A circuit board, characterized in that, The circuit board is provided with a surge protection circuit as described in any one of claims 1-4.

6. The circuit board according to claim 5, characterized in that, The circuit board includes a first common terminal, and the ground plane corresponding to the first common terminal is provided with a preset number of layer-swapping vias.

7. The circuit board according to claim 5, characterized in that, The circuit board includes a second common terminal, and the ground plane corresponding to the first common terminal and the ground plane corresponding to the second common terminal are connected at a single point.

8. An electronic device, characterized in that, The electronic device includes a surge protection circuit as described in any one of claims 1-4 or a circuit board as described in any one of claims 5-7.

9. A combined device, characterized in that, The combined device includes: a power adapter and the electronic device as described in claim 8.

10. The combined device according to claim 9, characterized in that, The power adapter includes an input port and a high-voltage resistor, and the input port is connected to the first common terminal through the high-voltage resistor.

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