An FTTR and ONU device external interface circuit

Abstract

This application discloses an external interface circuit for FTTR and ONU devices. The circuit includes: a first interface, a second interface, a serial port signal protection module, a voice protection module, a common-mode protection module, a differential-mode filtering module, and an overvoltage protection module. The first interface is electrically connected to the serial port signal protection module and the voice protection module; the second interface is electrically connected to the serial port signal protection module, the common-mode protection module, and the overvoltage protection module via the differential-mode filtering module. This application enables dual functionality of voice and serial port signals without requiring disassembly.

Description

Technical Field

[0001] This application belongs to the field of communication equipment technology, specifically relating to an external interface circuit for FTTR and ONU devices. Background Technology

[0002] Currently, in the production testing and after-sales maintenance of FTTR and ONU type terminal equipment, judging the operating status of the equipment usually requires disassembling the casing and connecting the testing equipment through the serial port. This method is not only cumbersome and time-consuming, but frequent disassembly and assembly can also easily lead to damage to the equipment structure or poor interface contact, increasing maintenance costs. In addition, traditional testing methods lack integrated protection design for serial port signals and voice lines, which can easily cause signal interference or hardware damage in complex electromagnetic environments or under sudden overvoltage conditions, affecting the stability and service life of the equipment. Utility Model Content

[0003] To address the shortcomings of existing technologies, the main objective of this application is to provide an external interface circuit for FTTR and ONU devices. Based on the original voice signal function, this application brings out serial port signals through idle pins, enabling dual functions of voice and serial port signals without the need for disassembly.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] An external interface circuit for FTTR and ONU devices is disclosed. The circuit includes: a first interface, a second interface, a serial port signal protection module, a voice protection module, a common-mode protection module, a differential-mode filtering module, and an overvoltage protection module. The first interface is electrically connected to the serial port signal protection module and the voice protection module. The second interface is electrically connected to the serial port signal protection module, the common-mode protection module, and the overvoltage protection module through the differential-mode filtering module.

[0006] Optionally, the ground reference pin of the first interface is connected to the first ground terminal to form a first node; the power input pin of the first interface is connected to the +3.3V power supply to form a third node; the first differential voice signal input pin of the first interface is connected to the first input terminal of the voice protection module; and the second differential voice signal input pin of the first interface is connected to the second input terminal of the voice protection module.

[0007] Optionally, the serial data transmission pin of the second interface is connected to the first input terminal of the common-mode protection module; the serial data reception pin of the second interface is connected to the second input terminal of the common-mode protection module; the first voice line differential signal pin of the second interface is connected to the first input terminal of the differential-mode filtering module; the second voice line differential signal pin of the second interface is connected to the second input terminal of the differential-mode filtering module; the ground pin of the second interface is connected to the third input terminal of the common-mode protection module; and the power supply pin of the second interface is connected to the input terminal of the serial signal protection module.

[0008] Optionally, the serial port signal protection module includes: a first inductor, a second inductor, a first TVS diode, and a second TVS diode, wherein the first end of the first inductor is connected to the first node, the second end of the first inductor is connected to the anode of the first TVS diode to form a second node, and the cathode of the first TVS diode is connected to the third node; the first end of the second inductor is connected to the third node, the second end of the second inductor serves as the input terminal of the serial port signal protection module and is connected to the power supply pin of the second interface to form a fourth node, the anode of the second TVS diode is connected to the second node, and the cathode of the second TVS diode is connected to the fourth node.

[0009] Optionally, the serial port signal protection module further includes a self-resetting fuse, which is connected in series between the first inductor and the first node.

[0010] Optionally, the voice protection module includes: a fifth inductor, a sixth inductor, a third TVS diode, and a fourth TVS diode, wherein the cathode of the third TVS diode serves as the first input terminal of the voice protection module and is connected to the first differential voice signal input pin of the first interface to form an eighth node; the cathode of the fourth TVS diode serves as the second input terminal of the voice protection module and is connected to the second differential voice signal input pin of the first interface to form a ninth node; the anodes of the third and fourth TVS diodes are jointly connected to the ground pin of the second interface to form a seventh node; the first end of the fifth inductor is connected to the eighth node, and the second end of the fifth inductor is connected to the first input terminal of the common-mode protection module to form a fifth node; the first end of the sixth inductor is connected to the ninth node, and the second end of the sixth inductor is connected to the second input terminal of the common-mode protection module to form a sixth node.

[0011] Optionally, the voice protection module further includes a magnetic bead connected in series between the fifth inductor and the eighth node.

[0012] Optionally, the common-mode protection module includes: a third inductor, a fourth inductor, and a fifth TVS diode, wherein the first end of the third inductor is connected to the third node, and the second end of the third inductor serves as the first input terminal of the common-mode protection module; the first end of the fourth inductor is connected to the first end of the third inductor, and the second end of the fourth inductor serves as the second input terminal of the common-mode protection module.

[0013] Optionally, the differential mode filtering module includes: a first capacitor, a second capacitor, a seventh inductor, and an eighth inductor, wherein the first end of the seventh inductor serves as the first input terminal of the differential mode filtering module and is connected to the first voice line differential signal pin of the second interface to form a tenth node, and the second end of the seventh inductor is connected to the first input terminal of the overvoltage protection module; the first end of the first capacitor is connected to the second input terminal of the overvoltage protection module, and the second end of the first capacitor is connected to the second ground terminal; the first end of the eighth inductor serves as the second input terminal of the differential mode filtering module and is connected to the second voice line differential signal pin of the second interface to form an eleventh node, and the second end of the eighth inductor is connected to the third input terminal of the overvoltage protection module; the first end of the second capacitor is connected to the tenth node, and the second end of the second capacitor is connected to the eleventh node.

[0014] Optionally, the overvoltage protection module employs a bidirectional thyristor protector, with both the first and second grounding pins of the bidirectional thyristor protector connected to the third grounding terminal; the first voice line Ring protection input pin of the bidirectional thyristor protector serves as the first input terminal of the overvoltage protection module, connected to the second terminal of the seventh inductor to form the twelfth node; the second voice line Ring protection input pin of the bidirectional thyristor protector is connected to the twelfth node; the gate control pin of the bidirectional thyristor protector serves as the second input terminal of the overvoltage protection module and is connected to the first terminal of the first capacitor; the second voice line Tip protection input pin of the bidirectional thyristor protector serves as the third input terminal of the overvoltage protection module and is connected to the second terminal of the eighth inductor to form the thirteenth node; and the first voice line Tip protection input pin of the bidirectional thyristor protector is connected to the thirteenth node.

[0015] This application can bring about the following technical effects:

[0016] This application integrates multiple protection modules, including serial port signal protection, voice protection, common-mode and differential-mode filtering, and overvoltage protection, into an external interface circuit designed in the FTTR and ONU devices. This enables the core function of detecting the operating status of the equipment without disassembling it. It retains the original voice communication capability and can directly obtain serial port signals through the interface, avoiding the operational risks of disassembling the casing required by traditional testing methods. This significantly improves testing efficiency and equipment safety. At the same time, the multi-level protection design effectively suppresses electromagnetic interference and overvoltage impacts, ensuring the stability and reliability of signal transmission. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit structure of an external interface circuit between an FTTR and an ONU device provided in one embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the circuit structure of an external interface circuit between an FTTR and an ONU device provided in another embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the circuit structure of an external interface circuit between an FTTR and an ONU device provided in another embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Figure 1 This application provides an exemplary embodiment of an external interface circuit between an FTTR and an ONU device, such as... Figure 1 As shown, the circuit includes: a first interface 10, a second interface 20, a serial port signal protection module 30, a voice protection module 40, a common-mode protection module 50, a differential-mode filtering module 60, and an overvoltage protection module 70. The first interface 10 is electrically connected to the serial port signal protection module 30 and the voice protection module 40. The second interface 20 is electrically connected to the serial port signal protection module 30, the common-mode protection module 50, and the overvoltage protection module 70 through the differential-mode filtering module 60.

[0025] In this embodiment, Figure 1 The circuit shown integrates multiple protection modules, including serial port signal protection, voice protection, common-mode and differential-mode filtering, and overvoltage protection, to achieve the core function of testing the operating status of the equipment without disassembling it. That is, while fully retaining the original voice communication capability, it can directly obtain serial port signals through the interface, thereby avoiding the operational risks of traditional testing that require disassembling the casing.

[0026] In another exemplary embodiment, the first interface 20 is an internal interface, for example, using a JB02 connector. The ground reference pin 1 of the JB02 connector is connected to the first ground terminal GND1 to form a first node N1; the power input pin 2 of the JB02 connector is connected to a +3.3V power supply to form a third node N3; the first differential voice signal input pin 3 of the JB02 connector is connected to the first input terminal of the voice protection module 40; and the second differential voice signal input pin 4 of the JB02 connector is connected to the second input terminal of the voice protection module 40.

[0027] In this embodiment, the first interface 20 serves as an internal hardware hub, undertaking dual core functions. First, the first interface 20 connects to the first ground terminal GND1 via pin 1 to form a reference node (N1), providing a stable ground reference for the entire circuit. Second, the first interface 20 connects to a +3.3V power supply via pin 2 to construct a power node (N3), directly powering the serial port signal protection module 30 and indirectly supporting the operation of other modules. Simultaneously, its pins 3 and 4 serve as a dedicated transmission channel for voice signals, directly importing the original voice signal into the voice protection module 40 for purification. By integrating power supply, ground reference, and signal input, this interface not only establishes a stable electrical environment for the internal circuit but also serves as the starting node for dual-path protection of serial port and voice signals, ensuring signal security and system reliability.

[0028] In another exemplary embodiment, the second interface 20 is an external communication interface, such as an RJ116P6C standard interface. The serial data transmission pin TX of the second interface 20 is connected to the first input terminal of the common-mode protection module 50; the serial data reception pin RX of the second interface 20 is connected to the second input terminal of the common-mode protection module 50; the first voice line differential signal pin L1TIP of the second interface 20 is connected to the first input terminal of the differential-mode filtering module 60; the second voice line differential signal pin L2TIP of the second interface 20 is connected to the second input terminal of the differential-mode filtering module 60; the ground pin GND of the second interface 20 is connected to the third input terminal of the common-mode protection module 50; and the power supply pin POWER of the second interface 20 is connected to the input terminal of the serial signal protection module 30.

[0029] In this embodiment, the second interface 20 adopts the RJ116P6C standard interface, which can achieve multi-functional integrated transmission through its multi-pin collaboration. The serial data transmission pin TX and the serial data reception pin RX are respectively connected to the two input terminals of the common-mode protection module 50, which can form a bidirectional protection channel for serial signals. The first voice line differential signal pin L1TIP and the second voice line differential signal pin L2TIP are connected to the differential mode filter module 60, which can form a high-frequency noise filtering path for voice signals. The ground pin GND is directly connected to the third input terminal of the common-mode protection module 50 to establish a unified grounding reference for external devices. The power supply pin POWER is connected to the serial signal protection module 30, which can realize the linkage between external power supply and internal protection circuit.

[0030] The second interface 20, through precise allocation of signal, power and ground lines, ensures electrical isolation between internal and external circuits while also providing signal transmission, noise suppression and overcurrent protection, serving as a key hardware carrier for device testing without disassembly and stable communication.

[0031] In another exemplary embodiment, the serial port signal protection module 30 includes: a first inductor L1, a second inductor L2, a first TVS diode D1, and a second TVS diode D2. The first end of the first inductor L1 is connected to the first node N1, and the second end of the first inductor L1 is connected to the anode of the first TVS diode D1 to form a second node N2. The cathode of the first TVS diode D1 is connected to the third node N3. The first end of the second inductor L2 is connected to the third node N3, and the second end of the second inductor L2 serves as the input terminal of the serial port signal protection module 30 and is connected to the power supply pin POWER of the second interface 20 to form a fourth node N4. The anode of the second TVS diode D2 is connected to the second node N2, and the cathode of the second TVS diode D2 is connected to the fourth node N4.

[0032] In this embodiment, the serial port signal protection module 30 achieves a dual protection mechanism through a combination of inductors and TVS diodes. First, the first inductor L1 and the second inductor L2 are connected in series between the ground node (N1) and the power node (N3), respectively, forming the first barrier for high-frequency noise suppression, which can effectively filter out electromagnetic interference on the serial port signal line. Second, the first TVS diode D1 and the second TVS diode D2 form a bidirectional transient voltage clamping network in a cross-connection manner. When a surge or electrostatic discharge occurs on the POWER pin or ground line (N2) of the second interface 20, the first TVS diode D1 and the second TVS diode D2 can quickly conduct and clamp the abnormal voltage to a safe range (such as ±15V) to prevent the 3.3V power rail from being damaged by the impact.

[0033] This module, through the synergistic effect of inductor filtering and TVS tube dynamic clamping, ensures the purity of serial port signal transmission and achieves nanosecond-level response overvoltage protection, enabling the second interface 20 to work stably in complex electromagnetic environments. At the same time, it controls the protection power consumption to the milliwatt level, balancing safety and energy efficiency.

[0034] In another exemplary embodiment, such as Figure 2 As shown, the serial port signal protection module 30 also includes a self-resetting fuse F, which is connected in series between the first inductor L1 and the first node N1.

[0035] In this embodiment, by connecting the resettable fuse F in series with the grounding path between the first inductor L1 and the first node N1, a critical overcurrent protection barrier can be formed. Under normal conditions, the resettable fuse F exhibits low impedance (e.g., <0.1Ω), ensuring normal signal return. When the TVS diodes (D1 and D2) experience excessive ground current (e.g., >500mA) due to continuous surge discharge, the resettable fuse F can transition to a high impedance state (e.g., >1kΩ) within milliseconds, forcibly cutting off the abnormal current path and protecting the inductor and TVS diodes from overheating damage. After the fault is cleared, the resettable fuse F automatically cools and resets without manual intervention.

[0036] The above improvements, through intelligent current limiting of the grounding path, can not only avoid the drawback of traditional fuses needing to be replaced, but also effectively improve the reliability of the module against multiple impacts, while maintaining signal integrity.

[0037] In another exemplary embodiment, the voice protection module 40 includes a fifth inductor L5, a sixth inductor L6, a third TVS diode D3, and a fourth TVS diode D4. The cathode of the third TVS diode D3 serves as the first input terminal of the voice protection module 40 and is connected to the first differential voice signal input pin 3 of the first interface 20 to form an eighth node N8. The cathode of the fourth TVS diode D4 serves as the second input terminal of the voice protection module 40 and is connected to the second differential voice signal input pin 4 of the first interface 20 to form a ninth node N9. The anodes of the third TVS diode D3 and the fourth TVS diode D4 are jointly connected to the ground pin GND of the second interface 20 to form a seventh node N7. The first end of the fifth inductor L5 is connected to the eighth node N8, and the second end of the fifth inductor L5 is connected to the first input terminal of the common-mode protection module 50 to form a fifth node N5. The first end of the sixth inductor L6 is connected to the ninth node N9, and the second end of the sixth inductor L6 is connected to the second input terminal of the common-mode protection module 50 to form a sixth node N6.

[0038] In this embodiment, the voice protection module 40, through the collaborative design of inductors and TVS diodes, can achieve dual protection of the voice channel. First, the fifth inductor L5 and the sixth inductor L6 are connected in series between the voice signal input node (N8 and N9) and the common-mode protection module 50, respectively, forming a differential-mode interference filtering network, which can effectively suppress electromagnetic noise outside the voice frequency band (300Hz-3.4kHz). Second, the third TVS diode D3 and the fourth TVS diode D4 adopt a common anode grounding structure, and their cathodes are directly connected to the voice signal input terminal. When the line encounters electrostatic discharge (such as ±8kV contact discharge), the third TVS diode D3 and the fourth TVS diode D4 can clamp the overvoltage to a safe level (such as ±5V) within 1ns and quickly discharge to the ground terminal through the seventh node N7.

[0039] This module provides surge current protection while maintaining low distortion (THD<0.1%) in the voice signal through cascaded protection of pre-inductor filtering and subsequent TVS transistor transient suppression, ensuring that the voice quality meets the standard requirements and avoiding attenuation of high-frequency signals.

[0040] In another exemplary embodiment, such as Figure 3 As shown, the voice protection module 40 also includes a magnetic bead FB, which is connected in series between the fifth inductor L5 and the eighth node N8.

[0041] In this embodiment, the ferrite bead FB is connected in series between the fifth inductor L5 and the eighth node N8, forming the first barrier for high-frequency noise suppression. The impedance characteristic of the ferrite bead FB can reach 600Ω at 100MHz, which can effectively attenuate radio frequency interference (such as 5GHz WiFi harmonics) while keeping the insertion loss of the 300Hz-3.4kHz voice band below 0.1dB. In addition, the ferrite bead FB can work in conjunction with the subsequent TVS diodes (D3 and D4) to form a two-stage protection architecture of "ferrite bead filtering + TVS clamping". According to actual measurements, the noise suppression ratio above 1GHz can be improved to -45dB, and the DC resistance of the ferrite bead FB itself has a negligible impact on the amplitude of the voice signal, thus balancing signal purity and anti-interference capability.

[0042] In another exemplary embodiment, the common-mode protection module 50 includes a third inductor L3, a fourth inductor L4, and a fifth TVS diode D5, wherein the first end of the third inductor L3 is connected to the third node N3, and the second end of the third inductor L3 serves as the first input terminal of the common-mode protection module 50; the first end of the fourth inductor L4 is connected to the first end of the third inductor L3, and the second end of the fourth inductor L4 serves as the second input terminal of the common-mode protection module 50.

[0043] In this embodiment, the common-mode protection module 50 can achieve efficient common-mode noise suppression through the combination of symmetrical inductors and TVS diodes. The third inductor L3 and the fourth inductor L4 adopt a parallel structure with the same winding direction. Their first ends are connected to the 3.3V power supply node (N3), and their second ends are respectively connected to the TX and RX signal lines of the external interface, forming a common-mode choke structure, which can provide attenuation of ≥30dB for common-mode interference (such as radio frequency noise) above 20MHz. The fifth TVS diode D5 is connected between the inductor output terminal and ground. When the signal line senses a lightning surge (such as 1kV / 1μs), it can trigger avalanche breakdown within a short time (5ns), limiting the common-mode voltage to a safe range (such as ±6V).

[0044] This module, through the combined effect of inductor filtering and TVS clamping, can ensure the integrity of 100Mbps high-speed serial port signals, meet a certain degree of anti-interference requirements, and has a static power consumption of less than 1mW, thus balancing signal quality and protection performance.

[0045] In another exemplary embodiment, the differential mode filtering module 60 includes a first capacitor C1, a second capacitor C2, a seventh inductor L7, and an eighth inductor L8. The first end of the seventh inductor L7 serves as the first input terminal of the differential mode filtering module 60 and is connected to the first voice line differential signal pin L1TIP of the second interface 20 to form a tenth node N10. The second end of the seventh inductor L7 is connected to the first input terminal of the overvoltage protection module 70. The first end of the first capacitor C1 is connected to the second input terminal of the overvoltage protection module 70, and the second end of the first capacitor C1 is connected to the second ground terminal GND2. The first end of the eighth inductor L8 serves as the second input terminal of the differential mode filtering module 60 and is connected to the second voice line differential signal pin L2TIP of the second interface 20 to form an eleventh node N11. The second end of the eighth inductor L8 is connected to the third input terminal of the overvoltage protection module 70. The first end of the second capacitor C2 is connected to the tenth node N10, and the second end of the second capacitor C2 is connected to the eleventh node N11.

[0046] In this embodiment, the differential mode filtering module 60 adopts an LC composite network architecture, which can achieve accurate differential mode noise filtering. The seventh inductor L7 and the eighth inductor L8 are connected in series on the voice signal channel (L1TIP and L2TIP), respectively, forming a π-type filtering network with the first capacitor C1 and the second capacitor C2. The second capacitor C2 is directly connected across the signal lines, which can provide attenuation of differential mode interference (such as power supply harmonics) above a certain frequency (e.g., 2kHz) by, for example, ≥40dB. The first capacitor C1 can form a low-impedance return path through the second ground terminal GND2, thereby effectively suppressing common ground noise.

[0047] This module, through the coordinated filtering of dual inductor choke and dual capacitor bypass, can improve the signal-to-noise ratio of the 50Hz-1MHz band to over 75dB while maintaining the insertion loss of the baseband voice signal (300Hz-3.4kHz) at <0.2dB, and control the group delay fluctuation within 50μs. This can block low-frequency interference such as power line coupling and ensure the purity and real-time performance of the voice signal.

[0048] In another exemplary embodiment, the overvoltage protection module 70 employs a bidirectional thyristor protector.

[0049] In this embodiment, the first ground pin Ground1 and the second ground pin Ground2 of the bidirectional thyristor protector are both connected to the third ground terminal GND3; the first voice line Ring protection input pin K1_Ring of the bidirectional thyristor protector serves as the first input terminal of the overvoltage protection module 70 and is connected to the second terminal of the seventh inductor L7 to form the twelfth node N12; the second voice line Ring protection input pin K2_Ring of the bidirectional thyristor protector is connected to the twelfth node N12; the gate control pin G_gate of the bidirectional thyristor protector serves as the second input terminal of the overvoltage protection module 70 and is connected to the first terminal of the first capacitor C1; the second voice line Tip protection input pin K2_Tip of the bidirectional thyristor protector serves as the third input terminal of the overvoltage protection module 70 and is connected to the second terminal of the eighth inductor L8 to form the thirteenth node N13, and the first voice line Tip protection input pin K1_Tip of the bidirectional thyristor protector is connected to the thirteenth node N13.

[0050] In this implementation, the overvoltage protection module 70 employs a bidirectional thyristor protector to construct an intelligent voltage clamping system. It uses a symmetrical topology where K1_Ring and K2_Ring are connected in parallel to the twelfth node N12, and K1_Tip and K2_Tip are connected in parallel to the thirteenth node N13. This, combined with the linkage between the G_gate pin and the filter capacitor (C1), forms a dual-channel overvoltage triggering mechanism. When the voice lines (L1TIP and L2TIP) encounter a surge voltage exceeding, for example, ±60V, the thyristor is triggered to conduct within a very short time (e.g., 1μs), rapidly discharging the abnormal current through the third ground terminal GND3, and automatically resetting after the voltage returns to normal.

[0051] This module, through bidirectional symmetrical protection and precise gate control, can withstand lightning currents such as 100A, while keeping the residual voltage below ±15V and the leakage current below 1μA. It effectively protects against differential / common mode mixed overvoltage surges and avoids malfunctions in normal voice signals (operating voltage of -48V to +52V), thus achieving a balance between protection performance and communication reliability.

[0052] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An external interface circuit for FTTR and ONU devices, characterized in that, The circuit includes: The system includes a first interface, a second interface, a serial port signal protection module, a voice protection module, a common-mode protection module, a differential-mode filtering module, and an overvoltage protection module. The first interface is electrically connected to the serial port signal protection module and the voice protection module; The second interface is electrically connected to the serial port signal protection module, the common mode protection module, and the overvoltage protection module through the differential mode filtering module.

2. The circuit according to claim 1, characterized in that, The ground reference pin of the first interface is connected to the first ground terminal to form a first node; the power input pin of the first interface is connected to the +3.3V power supply to form a third node; the first differential voice signal input pin of the first interface is connected to the first input terminal of the voice protection module; the second differential voice signal input pin of the first interface is connected to the second input terminal of the voice protection module.

3. The circuit according to claim 1, characterized in that, The serial data transmission pin of the second interface is connected to the first input terminal of the common-mode protection module; the serial data reception pin of the second interface is connected to the second input terminal of the common-mode protection module; the first voice line differential signal pin of the second interface is connected to the first input terminal of the differential-mode filtering module; the second voice line differential signal pin of the second interface is connected to the second input terminal of the differential-mode filtering module; the ground pin of the second interface is connected to the third input terminal of the common-mode protection module; and the power supply pin of the second interface is connected to the input terminal of the serial signal protection module.

4. The circuit according to claim 2, characterized in that, The serial port signal protection module includes: The first inductor, the second inductor, the first TVS diode, and the second TVS diode, wherein... The first end of the first inductor is connected to the first node, the second end of the first inductor is connected to the anode of the first TVS tube to form the second node, and the cathode of the first TVS tube is connected to the third node. The first end of the second inductor is connected to the third node, and the second end of the second inductor is connected to the power supply pin of the second interface as the input terminal of the serial port signal protection module to form the fourth node. The anode of the second TVS tube is connected to the second node, and the cathode of the second TVS tube is connected to the fourth node.

5. The circuit according to claim 4, characterized in that, The serial port signal protection module also includes: A resettable fuse is connected in series between the first inductor and the first node.

6. The circuit according to claim 1, characterized in that, The voice protection module includes: The fifth inductor, the sixth inductor, the third TVS diode, and the fourth TVS diode, among which, The cathode of the third TVS diode is connected to the first differential voice signal input pin of the first interface as the first input terminal of the voice protection module to form the eighth node. The cathode of the fourth TVS diode serves as the second input terminal of the voice protection module and is connected to the second differential voice signal input pin of the first interface to form the ninth node; The anodes of the third TVS diode and the fourth TVS diode are connected together to the ground pin of the second interface to form the seventh node. The first end of the fifth inductor is connected to the eighth node, and the second end of the fifth inductor is connected to the first input terminal of the common-mode protection module to form the fifth node; The first end of the sixth inductor is connected to the ninth node, and the second end of the sixth inductor is connected to the second input terminal of the common mode protection module to form the sixth node.

7. The circuit according to claim 6, characterized in that, The voice protection module also includes: A magnetic bead, which is connected in series between the fifth inductor and the eighth node.

8. The circuit according to claim 2, characterized in that, The common-mode protection module includes: The third inductor, the fourth inductor, and the fifth TVS diode, among which... The first end of the third inductor is connected to the third node, and the second end of the third inductor serves as the first input terminal of the common mode protection module. The first end of the fourth inductor is connected to the first end of the third inductor, and the second end of the fourth inductor serves as the second input terminal of the common-mode protection module.

9. The circuit according to claim 1, characterized in that, The differential filtering module includes: The first capacitor, the second capacitor, the seventh inductor, and the eighth inductor, wherein... The first end of the seventh inductor is connected to the first voice line differential signal pin of the second interface as the first input terminal of the differential mode filter module to form the tenth node, and the second end of the seventh inductor is connected to the first input terminal of the overvoltage protection module. The first terminal of the first capacitor is connected to the second input terminal of the overvoltage protection module, and the second terminal of the first capacitor is connected to the second ground terminal. The first end of the eighth inductor is connected to the second voice line differential signal pin of the second interface as the second input terminal of the differential mode filter module to form the eleventh node, and the second end of the eighth inductor is connected to the third input terminal of the overvoltage protection module. The first terminal of the second capacitor is connected to the tenth node, and the second terminal of the second capacitor is connected to the eleventh node.

10. The circuit according to claim 1, characterized in that, The overvoltage protection module uses a bidirectional thyristor protector, wherein, The first and second grounding pins of the bidirectional thyristor protector are both connected to the third grounding terminal. The first input terminal is connected to the second terminal of the seventh inductor to form the twelfth node; The second voice line Ring protection input pin of the bidirectional thyristor protector is connected to the twelfth node; The gate control pin of the bidirectional thyristor protector is connected to the first terminal of the first capacitor as the second input terminal of the overvoltage protection module. The second voice line Tip protection input pin of the bidirectional thyristor protector is connected to the second end of the eighth inductor as the third input terminal of the overvoltage protection module to form the thirteenth node. The first voice line Tip protection input pin of the bidirectional thyristor protector is connected to the thirteenth node.

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