User board of digital stored program control exchange
By adopting the detachable four-wire FXS voice interface module design in the user board of the digital program-controlled switch, the problem of high maintenance costs of the user board is solved, efficient user number customization and security improvement are achieved, and hardware costs and maintenance costs are reduced. .
Patent Information
- Application Number
- CN202420028109.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-05
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2034-01-05
AI Technical Summary
The maintenance costs of existing digital programmable switch user boards are high, and when the number of users is small, purchase and spare parts cause unnecessary expenses, resulting in idle hardware resources and increased costs.
Design a digital programmable switch user board, adopting a microcontroller, bus transceiver and multiple slots. The user module is a four-wire FXS voice interface module, which can be detachable and unplugged through the slot to realize the 32-channel user board Supports and only replaces the module without changing the entire user board when the module fails.
It reduces maintenance costs, saves hardware costs, improves the guarantee and safety of equipment, avoids idle performance, and achieves precise customization of the number of users and efficient maintenance.
Smart Images
Figure CN222283310U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of digital program-controlled switches, in particular to a user board of a digital program-controlled switch. Background Art
[0002] The user board is the basic component of a digital program-controlled user exchange. The first-generation user board supports 8 users per board, and the second-generation user board supports 16 users per board. With the upgrade of integrated circuit technology, the user board currently under development is the third generation, and each board supports 32 users. This means that the carrying capacity of user machines of the same size has doubled, while the cost has not changed much, which not only improves the profit margin, but also meets the user's needs for large capacity and miniaturization.
[0003] In the prior art, the general FXS user board has 16 lines of users. If one line is damaged, the damaged user board needs to be removed and repaired, and then replaced with a new user board. As a result, customers need to reserve 16-line user boards at all times, resulting in idle hardware resources. The maintenance cost is high. The number of users of traditional telephone program-controlled switches is multiplied by the number of 16-line users. For users with a small number of users, procurement and spare parts will cause unnecessary expenses and increase costs. At the same time, according to the number of user lines purchased by the customer, more 16-line user boards need to be added, which means that more machine frames need to be occupied, further increasing costs. Utility Model Content
[0004] In order to solve the technical problems of high repair and maintenance cost of user boards in the prior art, the utility model provides a user board of a digital program-controlled exchange.
[0005] The technical solution of the utility model to solve the above technical problems is as follows:
[0006] A user board of a digital program-controlled exchange comprises a microcontroller, a bus transceiver, a plurality of user modules and a plurality of slots, wherein the microcontroller is electrically connected to the bus transceiver via a full-duplex synchronous serial bus, each of the user modules is electrically connected to the microcontroller via at least one of the slots, each of the slots is a full-duplex synchronous serial bus slot, all of the user modules are four-wire FXS voice interface modules, and the bus transceiver is electrically connected to a motherboard of the digital program-controlled exchange via a PCM bus.
[0007] The beneficial effects of the utility model are: by designing each user module as an FXS voice interface module, and allowing the FXS voice interface module to be detachably connected to the bus transceiver through a slot, the 32-way user board completed by multiple four-wire FXS voice interface modules fully meets the design requirements, improves work efficiency, and saves hardware costs. It can accurately customize the number of users according to customer needs and avoid idle performance. It improves the efficiency of equipment maintenance. If the FXS voice interface module fails, it only needs to replace a new module without replacing the entire user board, which greatly improves the security and safety of the product.
[0008] On the basis of the above technical solution, the present invention can also be improved as follows.
[0009] Furthermore, each of the four-wire FXS voice interface modules includes two interface circuits; each of the interface circuits includes a Si32260 interface chip, a semiconductor overvoltage protector U3 and a semiconductor overvoltage protector U4, the gate of the semiconductor overvoltage protector U3 is connected to a power supply, the drain of the semiconductor overvoltage protector U3 is grounded, and the source of the semiconductor overvoltage protector U3 is respectively connected to the TIPA pin, RINGA pin, STIPC1 pin and SRINGC1 pin of the Si32260 interface chip; the gate of the semiconductor overvoltage protector U4 is connected to a power supply, the drain of the semiconductor overvoltage protector U4 is grounded, and the source of the semiconductor overvoltage protector U4 is respectively connected to the TIPB pin, RINGB pin, STIPC2 pin and SRINGC2 pin of the Si32260 interface chip, and the Si32260 interface chip in each of the interface circuits is connected to the full-duplex synchronous serial bus slot via a full-duplex synchronous serial bus.
[0010] Further, the semiconductor overvoltage protector U3 and the semiconductor overvoltage protector U4 are both of model TIS61089A, and the semiconductor overvoltage protector U3 includes a first source, a second source, a third source, a fourth source, a first drain, a second drain and a first gate; the first source is connected to the STIPC1 pin of the Si32260 interface chip through a resistor R12, and the second source is connected to the TIPA pin of the Si32260 interface chip; the third source is connected to the SRINGC1 pin of the Si32260 interface chip through a resistor R15, and the fourth source is connected to the RINGA pin of the Si32260 interface chip; the first drain and the second drain are both grounded, and the first gate is grounded through a series capacitor C11;
[0011] The semiconductor overvoltage protector U4 includes a fifth source, a sixth source, a seventh source, an eighth source, a third drain, a fourth drain and a second gate. The fifth source is connected to the STIPC2 pin of the Si32260 interface chip through a resistor R22, and the sixth source is connected to the TIPB pin of the Si32260 interface chip; the seventh source is connected to the SRINGC2 pin of the Si32260 interface chip through a resistor R26, and the eighth source is connected to the RINGB pin of the Si32260 interface chip; the third drain and the fourth drain are both grounded, and the second gate is grounded through a series capacitor C21.
[0012] Further, the second source is grounded via a series capacitor C15, the fourth source is grounded via a series capacitor C14, a capacitor C10 is connected between the second source and the fourth source, and two ends of the capacitor C10 are connected to the second source and the fourth source respectively;
[0013] The sixth source is grounded via a series capacitor C24, the eighth source is grounded via a series capacitor C23, a capacitor C20 is connected between the sixth source and the fourth source, and two ends of the capacitor C20 are respectively connected to the sixth source and the eighth source.
[0014] Further, the second source is connected to the STIPACA pin of the Si32260 interface chip through a series resistor R10 and a capacitor C8, and the second source is connected to the STIPACA pin of the Si32260 interface chip through a series resistor R13;
[0015] The fourth source is connected to the STIPDCA pin of the Si32260 interface chip through a series resistor R11 and a capacitor C9, and the fourth source is connected to the SRINGDCA pin of the Si32260 interface chip through a series resistor R14.
[0016] Furthermore, the interface circuit also includes a switching circuit, which is a MOS tube switching circuit, the gate of which is connected to the DCDRVA pin of the Si32260 interface chip; the source of the MOS tube switching circuit is connected to the SDCHA pin of the Si32260 interface chip through a series resistor R3; the source of the MOS tube switching circuit is also connected to the SDCLA pin of the Si32260 interface chip through a series resistor R4 and a resistor R5; the source of the MOS tube switching circuit is also grounded through the series resistor R5; and the drain of the MOS tube switching circuit is connected to a power supply.
[0017] Furthermore, the MOS transistor switch circuit includes a MOS transistor Q1 and a MOS transistor Q2; the gate of the MOS transistor Q1 is connected to the gate of the MOS transistor Q2, the source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2, and the drain of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2; the drain of the MOS transistor Q1 is connected to the power supply through the series inductor L1, and the drain of the MOS transistor Q1 is connected to the control voltage through the series capacitor C6 and the resistor R1.
[0018] Furthermore, the MOS transistor switch circuit also includes a switch diode D1 and a diode D2, the anode of the switch diode D1 is connected to the control voltage through the resistor R1, the cathode of the switch diode D1 is respectively connected to one end of the capacitor C6 and the anode of the diode D2, the other end of the capacitor C6 is connected to the drain of the MOS transistor Q1, and the cathode of the diode D2 is connected to the source of the MOS transistor Q1.
[0019] Furthermore, the gate of the MOS tube Q1 is grounded through a series resistor R2, the resistor R5 is connected to resistors R6, R7 and R8, and the resistors R6, R7 and R8 are all connected in parallel with the resistor R5; the positive electrode of the switching diode D1 is grounded through series capacitors C3, C4 and C5 respectively.
[0020] Furthermore, each of the four-wire FXS voice interface modules further comprises a power filter, a power input end of the power filter is connected to a power source, and a power output end of the power filter is connected to a power input end of the four-wire FXS voice interface module. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the structure of the utility model;
[0022] Figure 2 is a circuit diagram of the interface circuit;
[0023] Figure 3 is a circuit diagram of a switching circuit;
[0024] Figure 4 This is the circuit diagram of the power supply filter. DETAILED DESCRIPTION
[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0026] FXS stands for Foreign Exchange Station, which is a voice interface used for a line-end connection between a digital telephone exchange system and a POTS telephone.
[0027] It should be noted that the connection in the present invention refers to electrical connection through wires or conductors.
[0028] like Figure 1 As shown, this embodiment provides a user board of a digital program-controlled exchange, including a microcontroller, a bus transceiver, a plurality of user modules and a plurality of slots, wherein the microcontroller is electrically connected to the bus transceiver through a full-duplex synchronous serial bus, each of the user modules is electrically connected to the microcontroller through at least one of the slots, each of the slots is a full-duplex synchronous serial bus slot, all of the user modules are four-wire FXS voice interface modules, and the bus transceiver is electrically connected to the motherboard of the digital program-controlled exchange through a PCM bus. Among them, the microcontroller is preferably a single-chip microcomputer, and the bus transceiver is preferably a 74LV16246 chip. The full-duplex synchronous serial bus of the bus transceiver is electrically connected to the PCM bus of the motherboard of the exchange, that is, the serial bus interface of the microcontroller is electrically connected to the four-wire audio interface of the motherboard of the digital program-controlled exchange.
[0029] Each of the user modules is designed as a four-wire FXS voice interface module, and the four-wire FXS voice interface module is detachably connected to the bus transceiver through a slot. The 32-channel user board completed by eight four-wire FXS voice interface modules fully meets the design requirements. If one of the four-wire FXS voice interface modules fails, it only needs to be replaced with a new module without replacing the entire user board, thereby reducing the repair and maintenance costs.
[0030] The four-wire FXS voice interface module includes two interface circuits. Figure 2 As shown, each of the interface circuits includes a Si32260 interface chip, a semiconductor overvoltage protector U3, and a semiconductor overvoltage protector U4.
[0031] The Si32260 interface chip is an interface chip produced by Xingke. The gate of the semiconductor overvoltage protector U3 is connected to the power supply, the drain of the semiconductor overvoltage protector U3 is grounded, and the source of the semiconductor overvoltage protector U3 is connected to the TIPA pin, RINGA pin, STIPC1 pin and SRINGC1 pin of the Si32260 interface chip; the gate of the semiconductor overvoltage protector U4 is connected to the power supply, the drain of the semiconductor overvoltage protector U4 is grounded, and the source of the semiconductor overvoltage protector U4 is connected to the TIPB pin, RINGB pin, STIPC2 pin and SRINGC2 pin of the Si32260 interface chip. The Si32260 interface chips in the two interface circuits are connected to the full-duplex synchronous serial bus slot through a full-duplex synchronous serial bus. The PCLK pin, FSYNC pin, DTX pin and DRX pin of each Si32260 interface chip are electrically connected to the 74LV16246 chip bus interface through a full-duplex synchronous serial bus.
[0032] The model of the semiconductor overvoltage protector U3 is TIS61089A. The models of the semiconductor overvoltage protector U3 and the semiconductor overvoltage protector U4 are both TIS61089A. The semiconductor overvoltage protector U3 includes a first source, a second source, a third source, a fourth source, a first drain, a second drain and a first gate; the first source is connected to the STIPC1 pin of the Si32260 interface chip through a resistor R12, and the second source is connected to the TIPA pin of the Si32260 interface chip; the third source is connected to the SRINGC1 pin of the Si32260 interface chip through a resistor R15, and the fourth source is connected to the RINGA pin of the Si32260 interface chip; the first drain and the second drain are both grounded, and the first gate is grounded through a series capacitor C11. The first source of the semiconductor overvoltage protector U3 is used to connect to the network protocol interface TIP1 of the control telephone system, and the third source is used to connect to the Ethernet serial interface RING1 of the control telephone system.
[0033] The semiconductor overvoltage protector U4 includes a fifth source, a sixth source, a seventh source, an eighth source, a third drain, a fourth drain and a second gate. The fifth source is connected to the STIPC2 pin of the Si32260 interface chip through a resistor R22, and the sixth source is connected to the TIPB pin of the Si32260 interface chip; the seventh source is connected to the SRINGC2 pin of the Si32260 interface chip through a resistor R26, and the eighth source is connected to the RINGB pin of the Si32260 interface chip; the third drain and the fourth drain are both grounded, and the second gate is grounded through a series capacitor C21. The first source of the semiconductor overvoltage protector U4 is used to connect the network protocol interface TIP2 of the control telephone system, and the third source is used to connect the Ethernet serial interface RING2 of the control telephone system. By setting the semiconductor overvoltage protector U3 and the semiconductor overvoltage protector U4, the voltage safety is improved and the risk of component damage caused by overvoltage is prevented.
[0034] Specifically, the second source is grounded via a series capacitor C15, the fourth source is grounded via a series capacitor C14, a capacitor C10 is connected between the second source and the fourth source, and two ends of the capacitor C10 are connected to the second source and the fourth source respectively;
[0035] The sixth source is grounded via a series capacitor C24, the eighth source is grounded via a series capacitor C23, a capacitor C20 is connected between the sixth source and the fourth source, and two ends of the capacitor C20 are respectively connected to the sixth source and the eighth source.
[0036] In some embodiments, the second source is connected to the STIPACA pin of the Si32260 interface chip through a series resistor R10 and a capacitor C8, and the second source is connected to the STIPACA pin of the Si32260 interface chip through a series resistor R13; the fourth source is connected to the STIPDCA pin of the Si32260 interface chip through a series resistor R11 and a capacitor C9, and the fourth source is connected to the SRINGDCA pin of the Si32260 interface chip through a series resistor R14.
[0037] like Figure 3As shown, the interface circuit also includes a switch circuit, which is a MOS switch circuit, the gate of which is connected to the DCDRVA pin of the Si32260 interface chip; the source of which is connected to the SDCHA pin of the Si32260 interface chip through a series resistor R3; the source of which is connected to the SDCLA pin of the Si32260 interface chip through a series resistor R4 and a resistor R5; the source of which is connected to the ground through a series resistor R5; the drain of which is connected to the power supply. By setting the switch circuit, it is convenient to control the working state of the Si32260 interface chip through voltage enable.
[0038] In some embodiments, the MOS transistor switch circuit includes a MOS transistor Q1 and a MOS transistor Q2; the gate of the MOS transistor Q1 is connected to the gate of the MOS transistor Q2, the source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2, and the drain of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2; the drain of the MOS transistor Q1 is connected to the power supply through the series inductor L1, and the drain of the MOS transistor Q1 is connected to the control voltage through the series capacitor C6 and the resistor R1. Each of the MOS transistor switch circuits includes a MOS transistor Q1 and a MOS transistor Q2; the gate of the MOS transistor Q1 is connected to the gate of the MOS transistor Q2, the source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2, and the drain of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2; the drain of the MOS transistor Q1 is connected to the power supply through the series inductor L1, and the drain of the MOS transistor Q1 is connected to the control voltage through the series capacitor C6 and the resistor R1.
[0039] Specifically, the MOS transistor switch circuit further includes a switch diode D1 and a diode D2, the anode of the switch diode D1 is connected to the control voltage through the resistor R1, the cathode of the switch diode D1 is connected to one end of the capacitor C6 and the anode of the diode D2 respectively, the other end of the capacitor C6 is connected to the drain of the MOS transistor Q1, and the cathode of the diode D2 is connected to the source of the MOS transistor Q1. The gate of the MOS transistor Q1 is grounded through a series resistor R2, the resistor R5 is connected to a resistor R6, a resistor R7 and a resistor R8, and the resistor R6, the resistor R7 and the resistor R8 are all connected in parallel with the resistor R5; the anode of the switch diode D1 is grounded through a series capacitor C3, a capacitor C4 and a capacitor C5 respectively. The anode of the switching diode D1 is also connected to a resistor R1, that is, one end of the resistor R1 is connected to the anode of the switching diode D1, and the other end of the resistor R1 is connected to the external voltage signal VBATA or the external voltage signal VBATB, and the other end of the resistor R1 is connected to one end of the resistor R62, and the other end of the resistor R62 is connected to the external voltage signal SVBATA or the external voltage signal SVBATB. Among them, the external voltage signal VBATA and the external voltage signal SVBATA correspond to one of the Si32260 interface chips in the same user module; the external voltage signal VBATB and the external voltage signal SVBATB correspond to another Si32260 interface chip in the same user module.
[0040] like Figure 4 As shown, the four-wire FXS voice interface module also includes a power filter, each FXS voice interface module includes two power filters, each Si32260 interface chip is connected to a power filter, the power input end of the power filter is connected to the power supply, and the power output end of the power filter is connected to the power input end of the four-wire FXS voice interface module. The power filter includes a resistor R29, a resistor R30, a capacitor C28, a capacitor C29, a capacitor C30 and a capacitor C31; one end of the resistor R29 is connected to a 3.3V power supply voltage, and the other end of the resistor R29 is respectively connected to one end of the capacitor C28, one end of the capacitor C29 and the power supply end VDDA of the Si32260 interface chip; the other end of the capacitor C28 and the other end of the capacitor C29 are grounded; one end of the resistor R30 is connected to a 3.3V power supply voltage, and the other end of the resistor R30 is respectively connected to one end of the capacitor C30, one end of the capacitor C31 and the power supply end VDDD of the Si32260 interface chip, and the other end of the capacitor C30 and the other end of the capacitor C31 are both grounded.
[0041] The embodiment of the utility model designs each user module as an FXS voice interface module, and each FXS voice interface module is composed of two Si32260 interface chips; since each Si32260 interface chip supports two user interfaces, each FXS voice interface module only supports four user accesses. Therefore, by setting up multiple FXS voice interface modules to increase the number of user accesses, and allowing the FXS voice interface module to be detachably connected to the bus transceiver through a slot, the 32-way user board that can be completed by setting up eight four-wire FXS voice interface modules fully meets the design requirements, improves work efficiency, and saves hardware costs. The number of users can be accurately customized according to needs to avoid idle performance. The equipment maintenance efficiency is improved. If the FXS voice interface module fails, it only needs to be replaced with a new module, without replacing the entire user board, which greatly improves the security and safety of the product.
[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the concept and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A user board of a digital program-controlled exchange, characterized in that: It includes a microcontroller, a bus transceiver, multiple user modules and multiple slots. The microcontroller is electrically connected to the bus transceiver through a full-duplex synchronous serial bus, each user module is electrically connected to the microcontroller through at least one slot, each slot is a full-duplex synchronous serial bus slot, all the user modules are four-wire FXS voice interface modules, and the bus transceiver is electrically connected to the motherboard of the digital program-controlled switch through a PCM bus.
2. The user board of the digital program-controlled exchange according to claim 1, characterized in that: Each of the four-wire FXS voice interface modules includes two interface circuits; each of the interface circuits includes a Si 32260 interface chip, a semiconductor overvoltage protector U3 and a semiconductor overvoltage protector U4, the gate of the semiconductor overvoltage protector U3 is connected to a power supply, the drain of the semiconductor overvoltage protector U3 is grounded, and the source of the semiconductor overvoltage protector U3 is respectively connected to the TIPA pin, RINGA pin, STIPC1 pin and SRINGC1 pin of the Si 32260 interface chip; the gate of the semiconductor overvoltage protector U4 is connected to a power supply, the drain of the semiconductor overvoltage protector U4 is grounded, and the source of the semiconductor overvoltage protector U4 is respectively connected to the TIPB pin, RINGB pin, STIPC2 pin and SRINGC2 pin of the Si32260 interface chip, and the Si 32260 interface chip in each of the interface circuits is connected to the full-duplex synchronous serial bus slot via a full-duplex synchronous serial bus.
3. The user board of the digital program-controlled exchange according to claim 2, characterized in that: The semiconductor overvoltage protector U3 and the semiconductor overvoltage protector U4 are both of model TIS61089A, and the semiconductor overvoltage protector U3 includes a first source, a second source, a third source, a fourth source, a first drain, a second drain and a first gate; the first source is connected to the STIPC1 pin of the Si 32260 interface chip through a resistor R12, and the second source is connected to the TIPA pin of the Si32260 interface chip; the third source is connected to the SRINGC1 pin of the Si 32260 interface chip through a resistor R15, and the fourth source is connected to the RINGA pin of the Si 32260 interface chip; the first drain and the second drain are both grounded, and the first gate is grounded through a series capacitor C11; The semiconductor overvoltage protector U4 includes a fifth source, a sixth source, a seventh source, an eighth source, a third drain, a fourth drain and a second gate. The fifth source is connected to the STIPC2 pin of the Si 32260 interface chip through a resistor R22, and the sixth source is connected to the TIPB pin of the Si 32260 interface chip; the seventh source is connected to the SRINGC2 pin of the Si 32260 interface chip through a resistor R26, and the eighth source is connected to the RINGB pin of the Si 32260 interface chip; the third drain and the fourth drain are both grounded, and the second gate is grounded through a series capacitor C21.
4. The user board of the digital program-controlled exchange according to claim 3, characterized in that: The second source is grounded via a series capacitor C15, the fourth source is grounded via a series capacitor C14, a capacitor C10 is connected between the second source and the fourth source, and two ends of the capacitor C10 are connected to the second source and the fourth source respectively; The sixth source is grounded via a series capacitor C24, the eighth source is grounded via a series capacitor C23, a capacitor C20 is connected between the sixth source and the fourth source, and two ends of the capacitor C20 are respectively connected to the sixth source and the eighth source.
5. The user board of the digital program-controlled exchange according to claim 3, characterized in that: The second source is connected to the STIPACA pin of the Si 32260 interface chip through a series resistor R10 and a capacitor C8, and the second source is connected to the STIPACA pin of the Si 32260 interface chip through a series resistor R13; The fourth source is connected to the STIPDCA pin of the Si 32260 interface chip through a series resistor R11 and a capacitor C9, and the fourth source is connected to the SRINGDCA pin of the Si 32260 interface chip through a series resistor R14.
6. The user board of the digital program-controlled exchange according to claim 2, characterized in that: Each of the interface circuits also includes a switching circuit, which is a MOS tube switching circuit, wherein the gate of the MOS tube switching circuit is connected to the DCDRVA pin of the Si 32260 interface chip; the source of the MOS tube switching circuit is connected to the SDCHA pin of the Si 32260 interface chip through a series resistor R3; the source of the MOS tube switching circuit is also connected to the SDCLA pin of the Si32260 interface chip through a series resistor R4 and a resistor R5; the source of the MOS tube switching circuit is also grounded through the series resistor R5; and the drain of the MOS tube switching circuit is connected to a power supply.
7. The user board of the digital program-controlled exchange according to claim 6, characterized in that: The MOS transistor switch circuit includes a MOS transistor Q1 and a MOS transistor Q2; the gate of the MOS transistor Q1 is connected to the gate of the MOS transistor Q2, the source of the MOS transistor Q1 is connected to the source of the MOS transistor Q2, and the drain of the MOS transistor Q1 is connected to the drain of the MOS transistor Q2; the drain of the MOS transistor Q1 is connected to the power supply through a series inductor L1, and the drain of the MOS transistor Q1 is connected to the control voltage through a series capacitor C6 and a resistor R1.
8. The user board of the digital program-controlled exchange according to claim 7, characterized in that: The MOS transistor switch circuit also includes a switch diode D1 and a diode D2. The anode of the switch diode D1 is connected to the control voltage through the resistor R1. The cathode of the switch diode D1 is respectively connected to one end of the capacitor C6 and the anode of the diode D2. The other end of the capacitor C6 is connected to the drain of the MOS transistor Q1. The cathode of the diode D2 is connected to the source of the MOS transistor Q1.
9. The user board of the digital program-controlled exchange according to claim 8, characterized in that: The gate of the MOS tube Q1 is grounded through a series resistor R2, and the resistor R5 is connected to resistors R6, R7 and R8, and the resistors R6, R7 and R8 are all connected in parallel with the resistor R5; the positive electrode of the switch diode D1 is grounded through series capacitors C3, C4 and C5 respectively.
10. The user board of a digital program-controlled exchange according to any one of claims 1 to 9, characterized in that: Each of the four-wire FXS voice interface modules further comprises a power filter, a power input end of the power filter is connected to a power source, and a power output end of the power filter is connected to a power input end of the four-wire FXS voice interface module.