Protection circuit for a terminal and its charging interface

Abstract

The application relates to a terminal and a protection circuit of a charging interface thereof. The circuit comprises a differential signal transmission module, a first end of the differential signal transmission module being used for connecting a differential signal receiving module of the terminal; a first surge suppression module, a first end of the first surge suppression module being connected to a second end of the differential signal transmission module, and a second end of the first surge suppression module being used for grounding; an AC / DC grounding module, a first end of the AC / DC grounding module being connected to the first end of the first surge suppression module and the second end of the differential signal transmission module respectively, and a second end of the AC / DC grounding module being used for grounding; and a second surge suppression module, the second surge suppression module being connected to a differential signal line. In this way, the surge protection capability of the charging interface of the terminal can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic device charging protection, in particular to a terminal and a protection circuit of a charging interface thereof. BACKGROUND

[0002] In the field of circuit protection of electronic devices, the surge protection design for the USB interface of a mobile phone has always been the focus of the technical personnel in the field. At present, the industry generally adopts a protection scheme of configuring a TVS (Transient Voltage Suppression) diode and a 4.7Ω resistor on the mainboard for the DP / DM port of the USB interface of the mobile phone. This scheme can meet the general overvoltage and overcurrent protection requirements in the conventional charging port surge protection scene, and thus has become the basic protection scheme of the industry mainstream for a long period of time.

[0003] However, with the rapid iteration of the fast charging technology of smart phones, especially the wide application of high-power fast charging and multi-protocol compatible charging technologies, the surge impact environment faced by the charging port has changed significantly. The applicant found in the implementation process that the existing protection scheme gradually exposes the problem of insufficient protection capability. CONTENT OF THE UTILITY MODEL

[0004] Based on this, the purpose of the present application aims to at least solve one of the above technical defects, in particular the technical defect of poor protection capability in the prior art, and the present application provides a protection circuit of a terminal and a charging interface thereof.

[0005] In a first aspect, the present application provides a protection circuit of a charging interface of a terminal, which comprises:

[0006] a differential signal transmission module, a first end of the differential signal transmission module being used for connecting a differential signal receiving module of the terminal;

[0007] a first surge suppression module, a first end of the first surge suppression module being connected to a second end of the differential signal transmission module, and a second end of the first surge suppression module being used for grounding;

[0008] an AC / DC grounding module, a first end of the AC / DC grounding module being connected to the first end of the first surge suppression module and the second end of the differential signal transmission module respectively, and a second end of the AC / DC grounding module being used for grounding;

[0009] a second surge suppression module, which is connected to the differential signal line.

[0010] In one of the embodiments, a first end of the second surge suppression module is connected to the second end of the differential signal transmission module.

[0011] A second end of the second surge suppression module is connected to the second end of the first surge suppression module and the first end of the AC / DC grounding module respectively.

[0012] In one of the embodiments, the first end of the second surge suppression module is connected to the second end of the differential signal transmission module, the first end of the first surge suppression module and the first end of the AC / DC grounding module respectively.

[0013] The second end of the second surge suppression module is used for grounding.

[0014] In one of the embodiments, the first surge suppression module comprises:

[0015] a first surge suppression diode, the cathode of the first surge suppression diode being connected to the second end of the differential signal transmission module and the first end of the AC / DC grounding module respectively;

[0016] a second surge suppression diode, the anode of the second surge suppression diode being connected to the anode of the first surge suppression diode, and the cathode of the second surge suppression diode being used for grounding.

[0017] In one of the embodiments, the second surge suppression module comprises a third surge suppression diode and a fourth surge suppression diode;

[0018] the cathode of the third surge suppression diode being connected to the differential signal transmission module;

[0019] the anode of the fourth surge suppression diode being connected to the anode of the third surge suppression diode.

[0020] In one of the embodiments, the AC / DC grounding module comprises:

[0021] a capacitor unit, the first end of the capacitor unit being connected to the first end of the first surge suppression module and the second end of the differential signal transmission module respectively, and the second end of the capacitor unit being used for grounding;

[0022] an inductor unit, the first end of the inductor unit being connected to the first end of the capacitor unit, the first end of the first surge suppression module and the second end of the differential signal transmission module respectively, and the second end of the inductor unit being used for grounding.

[0023] In one of the embodiments, the differential signal transmission module comprises a first differential line and a second differential line;

[0024] The first differential line and the second differential line are both connected to the first surge suppression module, the AC / DC grounding module and the second surge suppression module.

[0025] In one of the embodiments, the circuit further comprises:

[0026] a resistance module, the first end of the resistance module being connected to the first port of the differential signal transmission module, and the second end of the resistance module being used for connecting the differential signal receiving module of the terminal.

[0027] In one of the embodiments, the second surge suppression module is further configured to access an external power supply.

[0028] In a second aspect, the present application provides a terminal comprising a differential signal receiving module and the protection circuit of the terminal charging interface.

[0029] From the above technical solutions, the embodiments of the present application have the following advantages:

[0030] The terminal and the protection circuit of the terminal charging interface provided by the present application form a multiple protection structure on the differential signal transmission path through the cooperative work of the multi-stage surge suppression module and the AC / DC grounding module, and simultaneously realize AC / DC signal isolation by using the AC / DC grounding module, effectively suppress the surge impact in the large current charging scene, improve the adaptability of the circuit layout, and have the advantages of improving the surge protection capability, optimizing the signal transmission stability, and enhancing the adaptability of the circuit layout. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 A related technical surge protection circuit provided for the embodiments of the present application;

[0033] Figure 2 A structure schematic diagram of the protection circuit of the terminal charging interface provided for the embodiments of the present application;

[0034] Figure 3 A structure schematic diagram of the specific setting of the second surge suppression module provided for the embodiments of the present application;

[0035] Figure 4 A structure schematic diagram of another specific setting of the second surge suppression module provided for the embodiments of the present application.

[0036] Explanation of reference signs:

[0037] 10-protection circuit of the terminal charging interface; 20-differential signal receiving module; 110-differential signal transmission module; 120-first surge suppression module; 130-AC / DC grounding module; 140-second surge suppression module. DETAILED DESCRIPTION

[0038] With reference to the drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the present application.

[0040] It can be understood that the terms "first", "second" and the like in the present application can be used to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish the first element from the second element. For example, without departing from the scope of the present application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0041] It can be understood that "connection" in the following embodiments, if the circuits, modules, units and the like connected to each other have the transmission of electrical signals or data, should be understood as "electrical connection", "communication connection" and the like.

[0042] It can be understood that "at least one" means one or more, and "multiple" means two or more. "At least part of the element" means part or all of the element.

[0043] As used herein, the singular forms "a", "an" and "the" can include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "comprise / comprising" or "have / having" specifies the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but does not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in the specification includes any and all combinations of the related listed items.

[0044] In the field of circuit protection of electronic devices, the surge protection design for mobile phone USB interface has always been the focus of the skilled in the art. At present, such as Figure 1As shown, the industry generally adopts a protection scheme of configuring a TVS (Transient Voltage Suppressor) diode and a 4.7Ω resistor on the motherboard for the DP / DM ports (USB_DP_DET, USB_DM_DET) of the mobile phone USB interface. After the DP / DM signal enters the motherboard through the BTB, it will first pass through a TVS, then pass through a 4.7Ω resistor, and finally enter the SOC internally (USB_HS_DP, USB_HS_DM), as shown in the following figure. This scheme can meet the general overvoltage and overcurrent protection requirements in the surge protection scene of the conventional charging port, and thus has become the mainstream basic protection scheme in the industry for a long period of time.

[0045] However, with the rapid iteration of smartphone fast charging technology, especially the wide application of high-power fast charging and multi-protocol compatible charging technology, the surge impact environment faced by the charging port has changed significantly. The existing protection scheme gradually exposes the problem of insufficient protection capability, which is specifically manifested in the difficulty in effectively responding to the direct surge impact suffered by the charging port. When such an impact occurs, it often causes the device to fail to charge or boot, seriously affecting product reliability and user experience.

[0046] In addition, in the product development process, the motherboard layout design is usually determined in the early stage of the project. Since the existing protection scheme does not fully consider the high-level surge protection requirements, when the project enters the later stage and it is found that the protection capability needs to be adjusted and optimized, the implementation of the improvement measures is often difficult and costly due to the limited layout space reserved on the motherboard, and even the original layout design may need to be overturned, greatly increasing the development cycle and production cost.

[0047] Therefore, in view of the problems of insufficient protection capability and difficult layout adjustment in the prior art, it is urgent to propose a new USB interface surge protection scheme that can effectively respond to high-energy surge impact and adapt to compact motherboard layout.

[0048] Based on this, the present application provides a terminal and a protection circuit for a charging interface thereof. Through the cooperative work of the multi-stage surge suppression module and the AC / DC grounding module, a multiple protection structure is formed on the differential signal transmission path, and at the same time, the AC / DC grounding module is used to realize AC / DC signal isolation, effectively suppressing the surge impact in the large current charging scene, improving the adaptability of the circuit layout, and having the advantages of improving the surge protection capability, optimizing the signal transmission stability, and enhancing the adaptability of the circuit layout.

[0049] In one exemplary embodiment, Figure 2 A structure diagram of a protection circuit 10 for a terminal charging interface provided by the embodiment of the present application is shown in Figure 2 As shown, the circuit includes a differential signal transmission module 110, a first surge suppression module 120, an AC / DC grounding module 130, and a second surge suppression module.

[0050] The first end of the differential signal transmission module 110 is used for connecting the differential signal receiving module 20 of the terminal.

[0051] The differential signal transmission module 110 can be a physical channel for carrying data communication, for example, a differential line pair can be used to establish a signal transmission link between the internal circuit of the terminal and an external device.

[0052] The first end of the first surge suppression module 120 is connected to the second end of the differential signal transmission module 110, and the second end of the first surge suppression module 120 is used for grounding.

[0053] The first surge suppression module 120 can be a transient voltage suppression unit, for example, a back-to-back diode structure can be used to form a primary surge discharge path at the end of signal transmission.

[0054] The first end of the AC / DC grounding module 130 is connected to the first end of the first surge suppression module 120 and the second end of the differential signal transmission module 110, respectively, and the second end of the AC / DC grounding module 130 is used for grounding.

[0055] The AC / DC grounding module 130 can be a composite grounding network, for example, a parallel capacitor and inductor can be used to filter out high-frequency interference and stabilize DC potential at the same time.

[0056] The second surge suppression module is connected to the differential signal line.

[0057] The second surge suppression module can be a distributed protection unit, for example, a bidirectional TVS device can be used to establish a secondary protection node on the signal transmission line.

[0058] The first end of the differential signal transmission module 110 can be connected to the internal circuit of the terminal, and the second end of the differential signal transmission module 110 can be connected to the first surge suppression module 120. The AC / DC grounding module 130 can be connected in parallel to the connection point of the first surge suppression module 120 and the differential signal transmission module 110. The second surge suppression module can be directly connected to the differential signal line, can form an independent grounding path, and can also be connected in series between the first end of the differential signal transmission module 110 and the second end of the differential signal transmission module 110.

[0059] Specifically, when a surge current invades the differential signal line, the second surge suppression module can perform primary energy absorption, and residual energy is conducted to the first surge suppression module 120 for secondary discharge through the differential signal transmission module 110. The capacitor unit contained in the AC / DC grounding module 130 can quickly respond to high-frequency interference components, and the inductor unit can suppress low-frequency fluctuations. In this way, the two-stage surge suppression module forms a time-progressive protection mechanism, which can implement staged processing at different stages of the shock waveform. The AC / DC grounding module 130 simultaneously processes AC and DC components through the parallel connection point, which can avoid potential imbalance caused by a single grounding method.

[0060] In this embodiment, through the cooperative work of the multi-stage surge suppression module and the AC / DC grounding module 130, a multiple protection structure is formed on the differential signal transmission path, and the AC / DC grounding module 130 is used to realize AC / DC signal isolation, effectively suppress the surge impact in the large current charging scene, improve the surge protection capability, and reduce the failure risk of single-point protection devices. The AC / DC mixed grounding method improves the suppression capability of complex interference signals. At the same time, the distributed protection structure provides more implementation possibilities for later circuit layout optimization, reducing the difficulty of scheme adjustment caused by space limitations.

[0061] As an example, the conventional scheme only sets a single-stage protection structure at the end of signal transmission, while the embodiment sets a distributed protection node on the signal transmission path. The prior art uses a single grounding method, while the embodiment realizes AC / DC frequency separation by parallel connection of capacitors and inductors.

[0062] In one exemplary embodiment, Figure 3 A structure diagram of a specific setting of a second surge suppression module provided by the embodiment of the present application is shown in FIG. 2. Figure 3 As shown in FIG. 2, the first end of the second surge suppression module is connected to the second end of the differential signal transmission module 110.

[0063] The second end of the second surge suppression module is connected to the second end of the first surge suppression module 120 and the first end of the AC / DC grounding module 130, respectively.

[0064] Exemplarily, the input end of the second surge suppression module can be directly connected to the end of the differential signal transmission path, for example, a transient voltage suppression diode can be used to form a protection branch parallel to the signal transmission path. The output end of the second surge suppression module can be connected to other levels of protection devices to form a common ground connection, which can be realized by a metallized via to form a three-end common connection, and a cooperative discharge path for multi-stage surge suppression is established.

[0065] Specifically, when a surge voltage invades through the differential signal line, the second surge suppression module establishes a discharge channel at the first stage of protection, and clamps the transient overvoltage to a safe value through the avalanche breakdown characteristics of its internal semiconductor structure. The second end of the module is connected to the first end of the first surge suppression module 120 and the first end of the AC / DC grounding module 130, so that the residual surge energy that is not completely absorbed can continue to be discharged to the ground along the parallel path. The capacitor unit and the inductor unit contained in the AC / DC grounding module 130 can form a wideband low-impedance path to provide rapid discharge of transient current when a surge event occurs, and maintain the potential stability of the signal ground in the steady state.

[0066] Optionally, the embodiment further proposes that the first end of the second surge suppression module is connected to the second end of the differential signal transmission module 110, and the second end of the second surge suppression module is connected to the second end of the first surge suppression module 120 and the first end of the AC / DC grounding module 130, respectively. Compared with the traditional technology, the traditional USB interface protection scheme only uses a single TVS diode in combination with a resistor for protection, and the surge absorption capacity is limited by the physical characteristics of a single device. The embodiment uses a cascaded layout of two-stage surge suppression modules, so that the first stage module absorbs the main surge energy, and the second stage module handles the residual peak voltage, and the two-stage modules form an energy distribution mechanism through the common ground connection. The introduction of the AC / DC grounding module 130 not only provides a rapid discharge path for high-frequency surges, but also avoids the signal attenuation problem caused by the resistor element in the traditional scheme.

[0067] In the embodiment, multi-stage layered protection of the charging port against high-voltage surge impact can be achieved, effectively reducing the failure risk of single-point protection devices. The common ground connection of the two-stage surge suppression modules reduces the space occupation required by the layout of discrete devices, and the wideband characteristics of the AC / DC grounding module 130 can adapt to the discharge requirements of surges of different frequencies, while improving the protection reliability and reserving physical space for later motherboard layout optimization.

[0068] In one exemplary embodiment, Figure 4 Another specific structure diagram of the second surge suppression module provided by the embodiment of the present application is shown in FIG. 4. Figure 4 As shown in FIG. 4, the first end of the second surge suppression module is connected to the second end of the differential signal transmission module 110, the first end of the first surge suppression module 120, and the first end of the AC / DC grounding module 130, respectively; and the second end of the second surge suppression module is used for grounding.

[0069] The second end of the differential signal transmission module 110 can be an end of a signal transmission path away from the internal circuit of the terminal, which can be implemented by a copper foil trace or a flexible circuit board line, and can serve as a main input node of surge impact energy. The first end of the AC / DC grounding module 130 can be a connection point with both high-frequency signal grounding and low-frequency DC grounding functions, which can be implemented by a composite circuit structure in which a capacitor and an inductor are connected in parallel, and is used to realize the coordinated discharge of surge energy of different frequencies.

[0070] As shown in the example, when a surge voltage acts on the second end of the differential signal transmission module 110, a surge current is discharged through a parallel path formed by the first surge suppression module 120 and the second surge suppression module. The first surge suppression module 120 clamps the forward surge through its internal diode structure, and the second surge suppression module forms a secondary channel independent of the main discharge path by being directly grounded, while absorbing the reverse surge energy. The capacitor unit in the AC / DC grounding module 130 quickly discharges the high-frequency surge component, and the inductor unit forms impedance matching for the low-frequency surge component. The connection nodes of the three modules form a common point structure in physical layout, so that the space occupation of the surge protection unit is compressed to a single area, avoiding the cross-wiring problem caused by dispersed layout in the traditional scheme.

[0071] Optionally, the traditional technology adopts a single TVS diode and resistor series structure, which can only form surge protection in a single direction, and the resistor element will introduce signal attenuation. The present embodiment realizes full-path discharge of bidirectional surge energy through the parallel configuration of the double surge suppression modules. The composite grounding mode of the AC / DC grounding module 130 expands the frequency coverage of surge suppression compared with a single capacitor grounding structure.

[0072] In the present embodiment, the problem of insufficient bidirectional surge impact suppression capability of the existing protection circuit is solved, and the difficulty of later layout optimization is reduced through module integration design. The multi-path surge discharge mechanism effectively prevents damage to the internal circuit of the terminal caused by transient overvoltage, and the common point connection structure simplifies the mainboard wiring design, so that the protection circuit realizes multi-level protection function integration in a limited space.

[0073] In one example embodiment, as shown in Figure 3 , Figure 4 The first surge suppression module 120 includes:

[0074] a first surge suppression diode TVS1, the cathode of the first surge suppression diode TVS1 being connected to the second end of the differential signal transmission module 110 and the first end of the AC / DC grounding module 130, respectively;

[0075] The second surge suppression diode TVS2 has its anode connected to the anode of the first surge suppression diode TVS1, and its cathode is used for grounding.

[0076] The first surge suppression diode can be a semiconductor device used to discharge forward surge current. For example, it can be implemented using a transient voltage suppression diode, with its cathode connected to the second terminal of the differential signal transmission module 110 to form a forward surge discharge path. The second surge suppression diode can be a semiconductor device used to discharge reverse surge current. For example, it can be implemented using a transient voltage suppression diode connected to the common anode of the first surge suppression diode, with its cathode grounded to form a reverse surge discharge path.

[0077] For example, when a forward surge voltage is applied to the second terminal of the differential signal transmission module 110, the first surge suppression diode conducts because the cathode voltage is higher than the anode voltage, and the surge current is discharged to the AC / DC grounding module 130 through this diode. When a reverse surge voltage occurs, the second surge suppression diode conducts because the anode voltage is lower than the cathode voltage, and the surge current is directly discharged to ground through this diode. The two diodes are interconnected through their anodes to form a common node, so that both positive and negative surge voltages are limited to the diode breakdown voltage range. The capacitor in the AC / DC grounding module 130 provides a low-impedance grounding path for high-frequency interference signals, and the inductor provides a low-impedance grounding path for DC surge current, thereby achieving the shunting of interference of different frequencies.

[0078] In this embodiment, bidirectional voltage clamping is achieved within a single module through two surge suppression diodes connected by a common anode, eliminating the need for additional reverse protection devices.

[0079] In one exemplary embodiment, such as Figure 3 , Figure 4 As shown, the second surge suppression module includes a third surge suppression diode TVS3 and a fourth surge suppression diode TVS4;

[0080] The cathode of the third surge suppression diode TVS3 is connected to the differential signal transmission module 110;

[0081] The anode of the fourth surge suppression diode TVS4 is connected to the anode of the third surge suppression diode TVS3.

[0082] The third surge suppression diode refers to a transient voltage suppression device with unidirectional conduction characteristics, for example, a Zener diode or a TVS diode can be used to achieve it, and the cathode is directly connected to the differential signal line to achieve rapid discharge of the forward surge voltage. The fourth surge suppression diode refers to a transient voltage suppression device with opposite polarity to the third surge suppression diode, for example, a Zener diode or a TVS diode in reverse parallel can be used to achieve it, and the anode forms a common node with the anode of the third surge suppression diode to build a discharge path for reverse surge current. The third surge suppression diode and the fourth surge suppression diode are interconnected by the anode to form a symmetrical structure, so that the two diodes can share the pad or package in physical layout.

[0083] Exemplarily, when a forward surge voltage occurs on the differential signal line, the third surge suppression diode is turned on because the cathode potential is higher than the anode, and the overvoltage current flows to the ground loop through the diode. When a negative surge voltage occurs, the fourth surge suppression diode is turned on because the anode potential is higher than the cathode, forming a reverse current discharge channel. The two diodes are interconnected by the anode to form a compact symmetrical layout, without the need for additional ground pads, and a bidirectional protection structure is directly built on both sides of the signal line. This connection method shortens the physical distance between the surge suppression path and the signal transmission path, reducing the influence of line parasitic inductance on protection response speed.

[0084] In this embodiment, a bidirectional protection is directly built on the signal line by two reverse parallel diodes, without relying on external ground path to complete the synchronous suppression of positive and negative surges. At the same time, the connection of the common anode of the diodes reduces the layout area of the protection device on the circuit board, saving the wiring space. Moreover, the integrated layout of the device reduces the occupation area of the protection circuit, adapting to the high-density wiring demand of the mobile terminal mainboard, and there is no need to redesign the PCB wiring due to protection circuit adjustment in the later stage.

[0085] In one exemplary embodiment, as shown in Figure 3 , Figure 4 The AC-DC grounding module 130 includes:

[0086] The first end of the capacitor unit is connected to the first end of the first surge suppression module 120 and the second end of the differential signal transmission module 110, respectively, and the second end of the capacitor unit is used for grounding;

[0087] The first end of the inductor unit is connected to the first end of the capacitor unit, the first end of the first surge suppression module 120, and the second end of the differential signal transmission module 110, respectively, and the second end of the inductor unit is used for grounding.

[0088] The capacitor unit can be an energy storage element with high-frequency signal conduction characteristics, which can be implemented by a multilayer ceramic capacitor, and the capacitance range can be set to 1 nF to 100 nF. When a high-frequency surge is encountered, the unit forms a low-impedance path to quickly introduce the transient overvoltage into the ground terminal. The inductor unit can be an electromagnetic element with direct current and low-frequency signal conduction characteristics, which can be implemented by a wire-wound power inductor, and the inductance range can be set to 1 μH to 100 μH. While maintaining direct current signal transmission, the unit establishes a low-frequency surge discharge path through magnetic saturation characteristics.

[0089] Exemplarily, the capacitor unit and the inductor unit can form a frequency band surge processing mechanism in a parallel structure. When a high-frequency surge signal invades the differential signal transmission module 110, the capacitor unit presents a low-impedance characteristic, and the high-frequency energy is discharged through the ground path within nanoseconds. For direct current charging signals and low-frequency interference signals, the inductor unit maintains a low-impedance state to ensure signal transmission stability, and when a low-frequency surge is encountered, the impedance characteristic can be changed through the magnetic core saturation effect to establish a current discharge channel. The common node connection of the two units realizes the physical isolation of alternating current and direct current signals, avoiding the interference of the high-frequency discharge loop on the direct current operating point.

[0090] In this embodiment, through the synergistic effect of the capacitor and the inductor, a surge protection network covering the entire frequency band is constructed, which realizes high-frequency transient suppression while preserving the integrity of the direct current signal. The modular structure integrates discrete devices into a single functional module, effectively reducing the circuit layout space. The realization of full-band surge suppression in an alternating current and direct current mixed signal environment solves the contradiction between the insufficient high-frequency response of the traditional protection scheme and the direct current signal interference. The complementary characteristics of the capacitor unit and the inductor unit ensure the stability of the signal transmission of the charging port, and the modular design provides a physical implementation basis for later maintenance optimization.

[0091] In one exemplary embodiment, as shown in Figure 3 、 Figure 4 The differential signal transmission module 110 includes a first differential line and a second differential line.

[0092] The first differential line and the second differential line are both connected with a first surge suppression module 120, an alternating current and direct current grounding module 130, and a second surge suppression module.

[0093] The first differential line and the second differential line can be two independent conductor lines for transmitting differential signals, which can be implemented by copper foil wiring or flexible circuit board wiring, for example, used to carry positive and negative phase signals in high-speed data transmission.

[0094] Exemplarily, two differential lines are each configured with an independent protection system, and a first surge suppression module 120 is connected between each differential line and the ground to form a symmetrical primary voltage clamping structure. An AC / DC grounding module 130 filters high-frequency noise interference through a parallel capacitor and establishes a DC grounding path using an inductor to ensure signal integrity. A second surge suppression module can be connected across the differential lines to form a common-mode noise suppression loop. When a surge voltage acts on both differential lines at the same time, the symmetrically arranged protection modules can trigger simultaneously to avoid signal imbalance caused by overload of single-sided protection elements.

[0095] In this embodiment, by independently configuring a complete protection system for each differential line, the positive and negative signal lines have completely consistent overvoltage protection characteristics, eliminating the risk of signal distortion caused by asymmetric protection. At the same time, the modularized discrete design allows the protection elements to be arranged dispersedly according to the mainboard space, breaking through the space limitation of traditional centralized protection layout. Symmetrical surge protection of differential signal lines is achieved, ensuring that the positive and negative signal lines remain synchronized in response when subjected to transient overvoltage impact, effectively preventing signal distortion caused by asymmetric protection. The independently configured protection module group forms a redundant protection mechanism, significantly improving the reliability of the interface in a complex electromagnetic environment. The modular layout provides flexible space for later optimization and adjustment, adapting to the engineering implementation needs of compact electronic devices.

[0096] In one exemplary embodiment, the circuit further comprises:

[0097] A resistance module, a first end of the resistance module being connected to a first port of the differential signal transmission module 110, and a second end of the resistance module being used to connect a differential signal receiving module 20 of a terminal.

[0098] The resistance module can be a circuit unit composed of a resistance element, for example, a surface mount resistor or a thin film resistor can be used to implement it, and the resistance range can be selected according to the signal transmission requirements. The resistance module can be connected in series in the signal transmission path, which can limit the peak value of the surge current and adjust the line impedance.

[0099] Exemplarily, the first end of the resistance module is directly connected to the first port of the differential signal transmission module 110, and the second end forms a physical conduction with the differential signal receiving module 20 of the terminal. When a surge current passes through the differential signal line, the resistance module generates a voltage drop through its impedance characteristics, converting part of the energy into heat energy consumption, thereby reducing the surge energy transmitted to the receiving module. At the same time, the series connection of the resistance module optimizes the impedance continuity of the signal path, suppressing the influence of signal reflection on the receiving end. The module adopts an independent packaging structure and can be directly installed without changing the original circuit layout, adapting to scenarios where the mainboard space is limited.

[0100] The embodiment adds an independent resistance module, retains the current limiting effect of the original resistance, realizes flexible resistance value adaptation through modular design, enhances the dispersion processing capability of transient large current, effectively improves the surge protection capability of the differential signal transmission path, avoids damage to the receiving module caused by current overload, and simplifies the complexity of later circuit adjustment.

[0101] In an exemplary embodiment, the second surge suppression module is also used for accessing an external power supply.

[0102] The second surge suppression module accessing the external power supply can mean that the conductive path of the module extends to the power input path of the charging interface, for example, a diode array or a varistor network can be used to realize this, and a bidirectional conduction semiconductor device is used to form a surge current discharge channel. The multi-path surge protection system can mean that the same module simultaneously covers the surge suppression requirements of the differential signal transmission path and the power input path, and the nonlinear voltage-current characteristics of the internal devices of the module are used to realize the coordinated action under different voltage thresholds.

[0103] Exemplarily, when a transient high-voltage surge occurs in the external power supply path, the second surge suppression module forms a low-impedance path through the connection point between the module and the power supply end, and guides the surge current to the ground end. The module establishes an electrical association between the differential signal transmission path and the power supply path, so that the overvoltage impact from the power supply end can be quickly discharged through the protection device inside the module, avoiding the influence of the surge energy on the signal transmission quality through common-mode interference. The modular design integrates the protection functions of the power supply path and the signal path in a single circuit structure, reducing the repeated design during the layout adjustment of the mainboard.

[0104] In some specific embodiments, the second surge suppression module can include a bidirectional transient voltage suppression diode, the anode of which is connected to the differential signal transmission line, and the cathode of which is connected to the voltage node of the power input end. In another embodiment, a series combination of a varistor and a gas discharge tube is arranged inside the module, wherein the varistor is connected across the signal line and the power line, and the gas discharge tube provides a large current discharge capability.

[0105] In the embodiment, the bidirectional access design of the module establishes an active protection mechanism between the power supply path and the signal path, eliminates the common-mode interference caused by the composite surge, and reduces the space occupation of the mainboard. It can effectively suppress the transient high-voltage impact introduced by the power supply path during the fast charging process, reduce the risk of damage to the charging circuit caused by the power supply surge, and reduce the circuit modification amount of later hardware optimization through the integrated protection module.

[0106] In an exemplary embodiment, the application also provides a terminal including a differential signal and a protection circuit of the terminal charging interface described above.

[0107] The differential signal transmission module can be a circuit structure for transmitting a differential signal, for example, can be implemented by using a differential line pair to establish a signal transmission channel between the terminal internal receiving module and the external charging interface, and ensure the integrity of the signal transmission path. The first surge suppression module can be a circuit unit for discharging surge energy, for example, can be implemented by using a series combination of diodes to form a primary discharge path between the differential signal transmission end and the ground to quickly absorb the forward surge energy. The AC / DC grounding module can be a grounding circuit that simultaneously processes AC and DC signals, for example, can be implemented by using parallel capacitors and inductors to filter out high-frequency interference and provide a DC grounding path through the inductor, solving the problem that the traditional single grounding method cannot simultaneously consider AC and DC characteristics. The second surge suppression module can be a protection circuit connected across the differential signal lines, for example, can be implemented by using a bidirectional diode structure to suppress common-mode interference by clamping the voltage between the differential lines, forming a bidirectional surge protection.

[0108] By way of example, the differential signal transmission module is directly connected to the terminal internal receiving module to form a main signal transmission path. The first surge suppression module is connected in parallel between the differential signal transmission end and the ground, and conducts to discharge energy when the surge voltage exceeds a threshold value. The AC / DC grounding module simultaneously provides high-frequency filtering and DC grounding functions on the signal line by using parallel capacitors and inductors, avoiding the high-frequency signal attenuation or DC potential offset caused by the single grounding method. The second surge suppression module is connected across the differential lines to bidirectionally clamp the voltage between the lines and suppress common-mode surge impact. The modules work cooperatively through a multi-level protection structure, the first surge suppression module handles single-line-to-ground surges, the second surge suppression module handles inter-line surges, and the AC / DC grounding module maintains signal stability, forming a composite protection system in a limited layout space.

[0109] Compared with the prior art, the existing scheme only uses a TVS diode and a resistor for single-level protection, which cannot cope with high-intensity surge impact, and the resistor layout occupies space, making it difficult to optimize later. The two-level discharge paths formed by the first and second surge suppression modules in the embodiment cover line-to-ground and inter-line surge scenarios; the AC / DC grounding module replaces the single resistor structure to reduce the number of discrete components while maintaining signal stability; the multi-module integrated design reduces the dependence on the main board layout space, and the topological connection relationship between the modules makes the protection function independent of the physical location of a single device.

[0110] Through the above technical solutions, the embodiment solves the problem of easy damage of the charging interface under direct surge impact, improves the surge energy absorption capacity through a multi-level protection structure, avoids equipment failure due to surge, and reduces the number of discrete components through modular design to reduce the occupation of the layout space, so that later circuit optimization does not need to adjust the physical location of multiple independent devices, improving design flexibility.

[0111] It should be noted that, Figures 1 to 4 The part ports and connection relationship of each module / unit are shown in the drawings, but other connection relationship of the ports of each module / unit can be set according to actual needs in actual application, and other pins or ports not shown can be set according to actual situation, Figures 1 to 4 The examples shown in the drawings are not intended to limit the present application.

[0112] It can be understood that the first surge suppression module, the AC / DC grounding module and the second surge suppression module can also adopt other forms, and are not limited to the forms mentioned in the above embodiments, as long as they can achieve the functions of surge suppression and AC grounding.

[0113] The above circuit can be applied to electronic terminals or similar devices with a charging interface, such as mobile phones, tablets or video game devices.

[0114] In the description of the present specification, the description of the terms "some embodiments", "other embodiments", "specific embodiments", "another embodiment", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0115] Finally, it should be noted that in this paper, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, article or device. Without more limitation, the element defined by the statement "including a…" does not exclude the presence of other identical elements in the process, article or device including the element.

[0116] The various embodiments in the present specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. Each embodiment can be combined as needed, and the same and similar parts refer to each other.

[0117] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A protection circuit for a terminal charging interface, characterized in that, The circuit includes: A differential signal transmission module, wherein the first end of the differential signal transmission module is used to connect to the differential signal receiving module of the terminal; A first surge suppression module, wherein a first end of the first surge suppression module is connected to a second end of the differential signal transmission module, and the second end of the first surge suppression module is used for grounding; An AC / DC grounding module, wherein the first end of the AC / DC grounding module is connected to the first end of the first surge suppression module and the second end of the differential signal transmission module, and the second end of the AC / DC grounding module is used for grounding; The second surge suppression module is connected to the differential signal line.

2. The circuit according to claim 1, characterized in that, The first end of the second surge suppression module is connected to the second end of the differential signal transmission module; The second end of the second surge suppression module is connected to the first end of the first surge suppression module and the first end of the AC / DC grounding module.

3. The circuit according to claim 1, characterized in that, The first end of the second surge suppression module is connected to the second end of the differential signal transmission module, the first end of the first surge suppression module, and the first end of the AC / DC grounding module, respectively. The second terminal of the second surge suppression module is used for grounding.

4. The circuit according to claim 1, characterized in that, The first surge suppression module includes: The first surge suppression diode has its cathode connected to the second terminal of the differential signal transmission module and the first terminal of the AC / DC grounding module, respectively. A second surge suppression diode is used, the anode of which is connected to the anode of the first surge suppression diode, and the cathode of the second surge suppression diode is used for grounding.

5. The circuit according to claim 1, characterized in that, The second surge suppression module includes a third surge suppression diode and a fourth surge suppression diode; The cathode of the third surge suppression diode is connected to the differential signal transmission module; The anode of the fourth surge suppression diode is connected to the anode of the third surge suppression diode.

6. The circuit according to any one of claims 1 to 5, characterized in that, The AC / DC grounding module includes: A capacitor unit, the first end of which is connected to the first end of the first surge suppression module and the second end of the differential signal transmission module, and the second end of the capacitor unit is used for grounding; An inductor unit, wherein the first end of the inductor unit is used to connect to the first end of the capacitor unit, the first end of the first surge suppression module, and the second end of the differential signal transmission module, and the second end of the inductor unit is used to ground.

7. The circuit according to any one of claims 1 to 5, characterized in that, The differential signal transmission module includes a first differential line and a second differential line; Both the first differential line and the second differential line are connected to the first surge suppression module, the AC / DC grounding module, and the second surge suppression module.

8. The circuit according to any one of claims 1 to 5, characterized in that, The circuit also includes: A resistor module, wherein the first end of the resistor module is connected to the first port of the differential signal transmission module, and the second end of the resistor module is used to connect to the differential signal receiving module of the terminal.

9. The circuit according to claim 1, characterized in that, The second surge suppression module is also used to connect to an external power source.

10. A terminal, characterized in that, It includes a differential signal receiving module and a protection circuit for the terminal charging interface as described in any one of claims 1-9.

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