Protection circuit for communication interface

Abstract

The invention relates to a protection circuit for a communication interface. The protection circuit comprises a transient signal suppression unit, a clamping unit, a control unit and a discharge unit, wherein the transient signal suppression unit is connected with the external interface and is used for releasing and reducing the voltage of a received transient high-voltage signal; the clamping unit is connected with the external interface and selectively outputs clamping voltage based on the received signal, and the voltage value of the clamping voltage is smaller than that of the received signal; the control unit is connected with the clamping unit and is used for controlling the discharge module to release the high-voltage signal based on the clamping voltage output by the clamping module; and the discharge unit is connected with the control unit, the first end of the discharge unit is connected with the external interface, the second end of the discharge unit is connected with the ground, and the discharge unit responds to the control of the control unit and transmits the transient high-voltage signal to the ground. According to the scheme, the protection effect of the communication interface is improved, stable operation of equipment is guaranteed, and the reliability and durability of an air conditioner communication system are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular provides a protection circuit for a communication interface. Background Art

[0002] With the widespread use of modern multi-split air-conditioning systems, subsystems such as outdoor units and indoor units need to communicate efficiently. However, when interacting with the building automation system (BAS), inconsistent device interfaces and voltage differences may cause communication failures or damage to the control panel. In addition, strong and weak electricity are deployed on the same line in the building, and the interference of strong electricity on weak electricity becomes a problem, especially strong high-voltage pulse signals, which may cause physical damage to communication. Peripheral equipment usually relies on low-voltage direct current, and long-distance transmission is susceptible to high-voltage interference and damage to equipment. Therefore, a solution is needed to prevent interference such as high-voltage pulses from damaging the air-conditioning communication system and equipment.

[0003] In the prior art, TVS is mostly used to weaken high-voltage pulses, but it cannot effectively weaken long-term high-voltage pulses, thereby damaging devices.

[0004] Accordingly, the art needs a new protection circuit for a communication interface to solve the above problems. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present invention is proposed to provide a solution or at least partially solve the technical problem in the prior art that the communication interface is difficult to resist long-term high-voltage pulses.

[0006] In a first aspect, the present invention provides a protection circuit for a communication interface, a transient signal suppression unit, a clamping unit, a control unit and a discharge unit; wherein the transient signal suppression unit is connected to an external interface, and releases and reduces the voltage of a received transient high-voltage signal; the clamping unit is connected to the external interface, and selectively outputs a clamping voltage based on a received signal, wherein a voltage value of the clamping voltage is less than a voltage value of the received signal; the control unit is connected to the clamping unit, and controls a discharge module to release a high-voltage signal based on the clamping voltage output by the clamping module; the discharge unit is connected to the control unit, a first end of the discharge unit is connected to the external interface, and a second end is connected to the ground, and in response to the control of the control unit, the transient high-voltage signal is transmitted to the ground.

[0007] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, the transient signal suppression unit is closer to the external interface than the clamping unit.

[0008] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the transient signal suppression unit includes a first transient voltage suppression diode TVS1 for suppressing differential mode signals and a second transient voltage suppression diode TVS2 and a third transient voltage suppression diode TVS3 for common mode signals; a first end of the first transient voltage suppression diode TVS1 is connected to a first end of the external interface, and the other end is connected to a second end of the external interface; a first end of the second transient voltage suppression diode TVS2 is connected to a first end of the external interface, and the other end is simultaneously connected to a first end of the third transient voltage suppression diode TVS3 and ground, and a second end of the third transient voltage suppression diode TVS3 is connected to the second end of the external interface.

[0009] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the clamping unit includes a Zener diode ZD1, a first resistor R1, a second resistor R2 and a first switching element; wherein the cathode of the Zener diode ZD1 is connected to the first end of the external interface, and the anode of the Zener diode ZD1 is connected to the first end of the first resistor R1; the second end of the first resistor R1 is simultaneously connected to the first end of the second resistor R2 and the control end of the first switching element, and the second end of the second resistor R2 is connected to the ground.

[0010] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the control unit includes a processor IC1, and the discharge unit includes a second switch element and a bias resistor RD; wherein the input end of the processor IC1 is connected to the output end of the first switch element, and the output end of the processor IC1 is connected to the control end of the second switch element, wherein the first end of the second switch element is connected to the first end of the external interface, the second end of the second switch element is connected to the ground, the first end of the bias resistor RD is connected to the control end of the second switch element, and the second end of the bias resistor RD is connected to the ground, and when the signal sent by the output end of the first switch element received by the processor IC1 is lower than a preset threshold, the processor IC1 controls the output end of the second switch element to be turned on to input the current of the external interface to the ground.

[0011] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the circuit further includes a third resistor R3, a fourth resistor, a first safety device and a second safety device; wherein the third resistor R3 is connected in parallel with the first safety device, the fourth resistor is connected in parallel with the second safety device, the first end of the first safety device is connected to the first end of the external interface, the first end of the second safety device is connected to the second end of the external interface, the second end of the first safety device is simultaneously connected to the first end of the first transient voltage suppression diode TVS1, the first end of the second transient voltage suppression diode TVS2 and the first end of the second switch element, the second end of the second safety device is simultaneously connected to the second end of the first transient voltage suppression diode TVS1 and the second end of the third transient voltage suppression diode TVS3, wherein the safety device is closed when the current passing through the safety device is greater than a preset condition.

[0012] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the discharge unit also includes a pull-up resistor RS and a pull-up power supply, wherein a first end of the pull-up resistor RS is connected to the output end of the pull-up power supply, and a second end of the pull-up resistor RS is simultaneously connected to the second end of the first switching element and the input end of the processor IC1, and when the first switching element is in an on state, the voltage at the second end of the pull-up resistor RS decreases.

[0013] As an alternative or supplement to the above scheme, in a method according to an embodiment of the present invention, the circuit also includes a first capacitor C1 and a second capacitor C2, wherein the first end of the first capacitor C1 is simultaneously connected to the control end of the first switching element, the second end of the first resistor R1 and the first end of the second resistor R2, and the second end of the first capacitor C1 is connected to the ground.

[0014] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention, when the second switching element is an IGBT, the circuit further includes an integrated power module or a drive circuit composed of an isolated power supply, a drive IC and a protection circuit.

[0015] As an alternative or supplement to the above solution, in a method according to an embodiment of the present invention,

[0016] The above one or more technical solutions of the present invention have at least one or more of the following Beneficial effects:

[0017] In the technical solution of the present invention, the transient high-voltage signal is quickly released and reduced in voltage through the transient signal suppression unit to ensure an immediate response. The clamping unit can selectively output a clamping voltage, which is lower than the received signal, further protecting the system from high-voltage damage. Combined with the control unit, the discharge unit can be accurately controlled to release the high-voltage signal according to the clamping voltage to ensure communication stability. The discharge unit quickly directs the transient high-voltage signal to the ground, reducing the burden on the system. Compared with the prior art, this solution effectively solves the problem of long-term high-voltage pulse weakening and significantly reduces the risk of device damage. Overall, this solution improves the protection effect of the communication interface, ensures the stable operation of the equipment, and greatly improves the reliability and durability of the air-conditioning communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0019] Figure 1 4 is a circuit diagram of a protection circuit for a communication interface according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0021] In the description of the present invention, "module" and "processor IC1" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, and memories, and may also include software parts, such as computer programs, or a combination of software and hardware. Processor IC1 may be a central processing unit IC1, a microprocessor IC1, an image processor IC1, a digital signal processor IC1 or any other suitable processor IC1. Processor IC1 has data and / or signal processing functions. Processor IC1 may be implemented in software, hardware or a combination of the two. Non-temporary computer-readable storage media include any suitable medium that can store computer programs, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B" and may include only A, only B or A and B. The singular terms "one" and "the" may also include plural forms.

[0022] The invention provides a protection circuit for a communication interface.

[0023] See attached Figure 1 , Figure 1 It is a main structural block diagram of a protection circuit for a communication interface according to an embodiment of the present invention.

[0024] like Figure 1 As shown, the protection circuit for the communication interface in the embodiment of the present invention mainly includes a transient signal suppression unit, a clamping unit, a control unit and a discharge unit.

[0025] In this embodiment, the above devices are described in detail as follows:

[0026] The transient signal suppression unit is connected to the external interface to release and reduce the voltage of the received transient high-voltage signal. The main function of the transient signal suppression unit is to process the received transient high-voltage signal, thereby protecting the internal circuit of the communication equipment from damage by the transient high-voltage signal.

[0027] Furthermore, the transient signal suppression unit is closely connected to the external interface. It should be noted that the close connection here means being closer to the external interface than other units. When an external transient high-voltage signal enters the interface, the transient signal suppression unit can quickly detect this abnormal signal and take immediate action. Through specific circuit design and material selection, the transient signal suppression unit can release these high-voltage signals in a very short time, selectively guide them to the ground wire, and at the same time reduce the voltage of the signal to a safe range, thereby protecting other parts of the equipment from being affected.

[0028] In this embodiment, preferably, the transient signal suppression unit includes a first transient voltage suppression diode TVS1 for suppressing differential mode signals and a second transient voltage suppression diode TVS2 and a third transient voltage suppression diode TVS3 for suppressing common mode signals.

[0029] The specific connection mode is that the first end of the first transient voltage suppression diode TVS1 is connected to the first end of the external interface, and the other end is connected to the second end of the external interface. The first end of the second transient voltage suppression diode TVS2 is connected to the first end of the external interface, and the other end is simultaneously connected to the first end of the third transient voltage suppression diode TVS3 and the ground, and the second end of the third transient voltage suppression diode TVS3 is connected to the second end of the external interface.

[0030] The first transient voltage suppression diode TVS1 is responsible for suppressing differential mode signals. Differential mode signals are usually signals that appear between two wires, which are complementary to the ground wire. In this design, the first end of the first transient voltage suppression diode TVS1 is connected to the first end of the external interface, and the other end is connected to the second end of the external interface. This configuration ensures that when a differential mode transient signal appears, the diode can conduct electricity quickly and guide the high voltage signal to the ground wire, thereby protecting the equipment.

[0031] The second transient voltage suppression diode TVS2 and the third transient voltage suppression diode TVS3 work together to suppress common-mode signals. Common-mode signals refer to the same signal that appears on two wires at the same time. In this design, the first end of the second transient voltage suppression diode TVS2 is connected to the first end of the external interface, and the other end is simultaneously connected to the first end of the third transient voltage suppression diode TVS3 and the ground wire. This means that when a common-mode transient signal appears, the two diodes will form a channel to quickly guide the high-voltage signal to the ground wire. At the same time, the second end of the third transient voltage suppression diode TVS3 is connected to the second end of the external interface to ensure that the common-mode signal can be effectively suppressed from both directions.

[0032] This specific connection method provides a powerful and flexible protection mechanism. Whether it is differential or common mode signals, the three TVS diodes are able to react quickly and provide the required protection.

[0033] In this embodiment, the transient signal suppression unit is an important component in the protection circuit for the communication interface, which can effectively protect the device from damage by transient high-voltage signals and ensure stable and reliable operation of the device.

[0034] The clamping unit is connected to the external interface and selectively outputs a clamping voltage based on a received signal, wherein a voltage value of the clamping voltage is smaller than a voltage value of the received signal.

[0035] Preferably, in one embodiment, the clamping unit includes a voltage-stabilizing diode ZD1, a first resistor R1, a second resistor R2, and a first switch element. The cathode of the voltage-stabilizing diode ZD1 is connected to the first end of the external interface, and the anode of the voltage-stabilizing diode ZD1 is connected to the first end of the first resistor R1; the second end of the first resistor R1 is simultaneously connected to the first end of the second resistor R2 and the control end of the first switch element, and the second end of the second resistor R2 is connected to the ground.

[0036] In this embodiment, the voltage zener diode ZD1 is the core component of the clamping unit. Under normal working conditions, the voltage zener diode ZD1 is in a closed state and has no effect on the signal. However, when encountering a transient high-voltage signal, the voltage zener diode ZD1 will be broken down and start to work. At this time, it will generate an appropriate reverse voltage, which is used to control the on or off state of the first switch element. Therefore, the voltage zener diode ZD1 plays both a protective role and a control role.

[0037] In this embodiment, the first resistor R1 and the second resistor R2 mainly play the role of voltage division and current limitation. When the voltage zener diode ZD1 is broken down, the first resistor R1 and the second resistor R2 will form a voltage division network with the voltage zener diode ZD1, which helps to stabilize the current flowing through the switch element and ensure that the switch element operates within a safe current range. In addition, through these two resistors, the reverse voltage after the breakdown can also be adjusted to more accurately control the behavior of the first switch element.

[0038] In this embodiment, the first switch element is normally closed because the control terminal does not have enough starting voltage, but when the voltage stabilizing diode ZD1 is broken down and generates a reverse voltage, this voltage is transmitted to the control terminal of the switch element, causing it to open.

[0039] When the external interface receives a transient high-voltage signal, the voltage-stabilizing diode ZD1 is broken down and starts to work, generating an appropriate reverse voltage. After being divided and adjusted by the first and second resistors R2, this voltage is transmitted to the control end of the first switch element to turn it on. When the first switch element is turned on, it will trigger the linkage of subsequent devices, so that the transient high-voltage signal can be quickly discharged, thus realizing the protection of the circuit.

[0040] In this embodiment, the switch element may be one of an IGBT, a MOS tube or a triode, or a simple combination of them into a triode-like structure commonly used in industry.

[0041] The control unit is connected to the clamping unit and controls the discharge module to release the high voltage signal based on the clamping voltage output by the clamping module. In this embodiment, the control unit is responsible for monitoring the clamping voltage output by the clamping unit and deciding when and how to release the high voltage signal through the discharge module accordingly to ensure the safe and stable operation of the overall circuit.

[0042] The discharge unit is connected to the control unit, a first end of the discharge unit is connected to the external interface, a second end of the discharge unit is connected to the ground, and in response to the control of the control unit, the transient high-voltage signal is transmitted to the ground.

[0043] In this embodiment, the control unit includes a processor IC1, and the discharge unit includes a second switch element and a bias resistor RD. The input end of the processor IC1 is connected to the output end of the first switch element, the output end of the processor IC1 is connected to the control end of the second switch element, the first end of the second switch element is connected to the first end of the external interface, the second end of the second switch element is connected to the ground, the first end of the bias resistor RD is connected to the control end of the second switch element, and the second end of the bias resistor RD is connected to the ground. When the signal sent by the output end of the first switch element received by the processor IC1 is lower than the preset threshold, the processor IC1 controls the output end of the second switch element to conduct and input the current of the external interface to the ground.

[0044] Preferably, the clamping unit also includes a pull-up resistor RS and a pull-up power supply, wherein the first end of the pull-up resistor RS is connected to the output end of the pull-up power supply, and the second end of the pull-up resistor RS is simultaneously connected to the second end of the first switching element and the input end of the processor IC1, wherein the voltage at the second end of the pull-up resistor RS is a clamping voltage, and when the first switching element is in the on state, the voltage at the second end of the pull-up resistor RS is reduced.

[0045] In this embodiment, the processor IC1 mainly monitors and determines in real time whether the signal (clamp signal) sent by the output end of the first switch element exceeds the preset threshold. When the processor IC1 detects that the signal exceeds the preset threshold, it will immediately generate a control signal and transmit it to the control end of the second switch element, thereby controlling the second switch element to be turned on or off.

[0046] The second switch element decides whether to quickly input the current of the external interface to the ground according to the instruction of the processor IC1. The main purpose of this action is to play a protective role and avoid damaging the circuit or equipment due to high current or voltage exceeding the threshold.

[0047] For the second switch element, its operation is completely based on the judgment of the processor IC1. Only when the processor IC1 determines that the signal output by the first switch element has exceeded the preset threshold, it will receive the instruction to turn on. After receiving such an instruction, the second switch element will be turned on immediately, which means that the current will flow to the ground quickly. This process is very fast, ensuring that the circuit and equipment are protected in time under high current or high voltage conditions.

[0048] It should be noted that when the second switching element is an IGBT (insulated gate bipolar transistor), there is a problem that the processor IC1 cannot directly drive the IGBT. The IGBT requires an appropriate gate voltage to turn on and off. Usually, this voltage is much higher than the output capacity of the processor IC1. Therefore, in this embodiment, when the second switching element is an IGBT, there is a drive circuit between the processor IC1 and the IGBT. The task of this drive circuit is to receive the low voltage, low current signal of the processor IC1 and convert it into a high voltage, high current drive signal to drive the IGBT. This not only ensures that the IGBT can be driven correctly, but also provides protection for the processor IC1 to be isolated from high voltage and high current.

[0049] In this embodiment, when the processor IC1 detects that the IGBT needs to be turned on, it sends a signal to the driver circuit. The driver circuit then generates an appropriate high voltage signal to turn on the IGBT. Conversely, when the processor IC1 decides to turn off the IGBT, the driver circuit pulls down the gate voltage of the IGBT to ensure that the IGBT is turned off.

[0050] In this embodiment, the drive circuit includes an integrated power module (IPM). In another embodiment, the drive circuit includes an isolated power supply, a driver IC, and a protection circuit. In this embodiment, the isolated power supply is implemented by a DC-DC converter or a transformer. The driver IC receives a signal from the processor IC1 and generates an appropriate high voltage, high current drive signal. The protection circuit includes an anti-parallel diode, a transient voltage suppressor, and a current detection circuit. These are all to ensure that the IGBT will not be damaged under various possible fault conditions.

[0051] In the clamp unit, the pull-up power supply provides a stable current and voltage to the pull-up resistor RS, ensuring that the resistor can accurately reflect the state of the circuit. When the circuit receives a high voltage signal, the first switch element will be activated. In this case, the voltage of the pull-up resistor RS will change immediately. The processor IC1 will quickly detect this change and determine whether action is needed. If the voltage change exceeds the preset range, it means that the circuit is facing a potential risk. The processor IC1 will immediately respond and send an instruction to the second switch element to turn it on and quickly flow the high current to the ground. In this way, the circuit and equipment are protected.

[0052] Through this design, the clamping unit can monitor and respond to possible risks in the circuit in real time, ensuring the safe and stable operation of the circuit and equipment.

[0053] In this embodiment, a first capacitor C1 and a second capacitor C2 are also included for filtering, wherein the first end of the first capacitor C1 is simultaneously connected to the control end of the first switch element, the second end of the first resistor R1 and the first end of the second resistor R2, and the second end of the first capacitor C1 is connected to the ground. The first end of the second capacitor C2 is connected to the second end of the pull-up resistor RS, and the second end of the second capacitor C2 is connected to the ground. The first capacitor C1 mainly plays the role of a filter in the circuit, helping to smooth the fluctuations of voltage and current. Since it is directly connected to the control end of the first switch element, the first resistor R1 and the second resistor R2, it can quickly react to the voltage and current changes in the circuit, thereby resisting sudden high-voltage shocks or transient disturbances. The second capacitor C2 is directly connected to the pull-up resistor RS and is connected to the ground. This configuration enables the second capacitor C2 to play a decoupling role in the circuit, helping to isolate the interference between the pull-up resistor RS and other circuit parts. In addition, the second capacitor C2 can also provide a stable reference voltage for the pull-up resistor RS.

[0054] In this embodiment, the circuit further includes a third resistor R3, a fourth resistor, a first safety device and a second safety device. The third resistor R3 is connected in parallel with the first safety device, the fourth resistor is connected in parallel with the second safety device, and the first end of the first safety device is connected to the first end of the external interface. The first end of the second safety device is connected to the second end of the external interface, the second end of the first safety device is simultaneously connected to the first end of the first transient voltage suppression diode TVS1, the first end of the second transient voltage suppression diode TVS2 and the first end of the second switch element, and the second end of the second safety device is simultaneously connected to the second end of the first transient voltage suppression diode TVS1 and the second end of the third transient voltage suppression diode TVS3. When the current passing through the safety device is greater than the preset condition, the safety device is closed.

[0055] In this embodiment, the third resistor R3 is configured in parallel with the first safety device, which means that current can flow through both at the same time. Under normal working conditions, most of the current will flow through the resistor, and only a small amount of current will flow through the safety device. However, when an abnormality occurs in the circuit, causing the current to increase rapidly, the safety device will exceed its preset conditions and disconnect, cutting off the connection between the subsequent circuit part and the power supply to prevent high current from damaging the circuit. Similar to the third resistor R3 and the first safety device, the fourth resistor is also connected in parallel with the second safety device. This design also ensures the safe diversion of current and provides additional protection in abnormal situations.

[0056] This part of the circuit is designed mainly to provide multiple protection measures. The combination of the third and fourth resistors, two fuses and multiple transient voltage suppression diodes ensures that the circuit can work safely and reliably under various adverse conditions. This design fully considers various abnormal situations that may occur and provides effective countermeasures for them, thus ensuring the stability and durability of the entire system.

[0057] In this embodiment, the input end of the processor IC1 can detect the signal sent by the output end of the first switch element within a period of time. By analyzing these signals, the interference frequency can be obtained, that is, the interference severity level of the environment in which the device is located can be effectively judged. In this embodiment, that is, the frequency when the signal sent by the output end of the first switch element is lower than the preset threshold is analyzed, that is, the falling edge frequency of the voltage is analyzed. If a large number of falling edges are detected within a specific time window, it can be judged that the external environment interference at this time is very frequent. On the contrary, if the number of falling edges is small, the interference is relatively weak.

[0058] Combined with this detection mechanism, the processor IC1 can respond dynamically to adapt to the current interference environment. Preferably, in this embodiment, the processor IC1 dynamically adjusts the on and off time of the second switch element based on the interference frequency by adjusting the frequency and duty cycle of PWM (pulse width modulation). This dynamic adjustment ensures that the device can still operate stably even in an environment with strong interference.

[0059] In addition, when the interface is a communication signal, especially when the baud rate is low, the design of this solution ensures that the high-voltage interference energy can be dynamically discharged without affecting the communication, further enhancing the reliability and stability of the communication equipment. This means that in real applications, even if the device is in a high-interference environment, it can still ensure accurate data transmission, greatly improving the robustness of the system.

[0060] Those skilled in the art will appreciate that the modules in the device can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principle of the present invention, and therefore, the technical solutions after splitting or merging will fall within the protection scope of the present invention.

[0061] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A protection circuit for a communication interface, characterized in that: include: A transient signal suppression unit, a clamping unit, a control unit and a discharge unit; The transient signal suppression unit is connected to the external interface to release and reduce the voltage of the received transient high-voltage signal; A clamping unit connected to the external interface, selectively outputting a clamping voltage based on a received signal, wherein a voltage value of the clamping voltage is less than a voltage value of the received signal; A control unit, connected to the clamping unit, controls the discharge module to release the high voltage signal based on the clamping voltage output by the clamping module; The discharge unit is connected to the control unit, a first end of the discharge unit is connected to the external interface, a second end of the discharge unit is connected to the ground, and in response to the control of the control unit, the transient high-voltage signal is transmitted to the ground.

2. The protection circuit for a communication interface according to claim 1, characterized in that: The transient signal suppression unit is closer to the external interface than the clamping unit.

3. The protection circuit for a communication interface according to claim 1, characterized in that: The transient signal suppression unit includes a first transient voltage suppression diode TVS1 for suppressing differential mode signals and a second transient voltage suppression diode TVS2 and a third transient voltage suppression diode TVS3 for suppressing common mode signals; A first end of the first transient voltage suppression diode TVS1 is connected to a first end of the external interface, and the other end is connected to a second end of the external interface; The first end of the second transient voltage suppression diode TVS2 is connected to the first end of the external interface, and the other end is connected to the first end of the third transient voltage suppression diode TVS3 and the ground. The second end of the third transient voltage suppression diode TVS3 is connected to the second end of the external interface.

4. The protection circuit for a communication interface according to claim 3, characterized in that: The clamping unit includes a voltage stabilizing diode ZD1, a first resistor R1, a second resistor R2 and a first switch element; The cathode of the voltage zener diode ZD1 is connected to the first end of the external interface, and the anode of the voltage zener diode ZD1 is connected to the first end of the first resistor R1; The second end of the first resistor R1 is connected to the first end of the second resistor R2 and the control end of the first switch element at the same time, and the second end of the second resistor R2 is connected to the ground.

5. The protection circuit for a communication interface according to claim 4, characterized in that: The control unit includes a processor IC1, and the discharge unit includes a second switch element and a bias resistor RD; The input end of the processor IC1 is connected to the output end of the first switch element, the output end of the processor IC1 is connected to the control end of the second switch element, the first end of the second switch element is connected to the first end of the external interface, the second end of the second switch element is connected to the ground, the first end of the bias resistor RD is connected to the control end of the second switch element, and the second end of the bias resistor RD is connected to the ground; When the signal sent by the output terminal of the first switch element received by the processor IC1 is lower than a preset threshold, the processor IC1 controls the output terminal of the second switch element to be turned on to input the current of the external interface to the ground.

6. The protection circuit for a communication interface according to claim 5, characterized in that: The circuit also includes a third resistor R3, a fourth resistor, a first safety device and a second safety device; The third resistor R3 is connected in parallel with the first safety device, the fourth resistor is connected in parallel with the second safety device, the first end of the first safety device is connected to the first end of the external interface, the first end of the second safety device is connected to the second end of the external interface, the second end of the first safety device is simultaneously connected to the first end of the first transient voltage suppression diode TVS1, the first end of the second transient voltage suppression diode TVS2 and the first end of the second switch element, the second end of the second safety device is simultaneously connected to the second end of the first transient voltage suppression diode TVS1 and the second end of the third transient voltage suppression diode TVS3, wherein the safety device is closed when the current passing through the safety device is greater than a preset condition.

7. The protection circuit for a communication interface according to claim 5, characterized in that: The clamping unit also includes a pull-up resistor RS and a pull-up power supply. The first end of the pull-up resistor RS is connected to the output end of the pull-up power supply, and the second end of the pull-up resistor RS is connected to the second end of the first switch element and the input end of the processor IC1 at the same time, wherein the voltage at the second end of the pull-up resistor RS is a clamping voltage, and when the first switch element is in the on state, the voltage at the second end of the pull-up resistor RS decreases.

8. The protection circuit for a communication interface according to claim 7, characterized in that: The circuit further includes a first capacitor C1 and a second capacitor C2. The first end of the first capacitor C1 is connected to the control end of the first switch element, the second end of the first resistor R1 and the first end of the second resistor R2, and the second end of the first capacitor C1 is connected to the ground; A first end of the second capacitor C2 is connected to the second end of the pull-up resistor RS, and a second end of the second capacitor C2 is connected to the ground.

9. The protection circuit for a communication interface according to claim 2, characterized in that: When the second switch element is an IGBT, the circuit further includes an integrated power module or a drive circuit consisting of an isolated power supply, a drive IC and a protection circuit.

10. The protection circuit for a communication interface according to claim 5, characterized in that: The input end of the processor IC1 acquires the signal sent by the output end of the first switch element within a period of time, and obtains the interference frequency based on the signal sent by the output end of the first switch element within a period of time; The processor IC1 dynamically adjusts the on and off time of the second switch element using the frequency and duty cycle of the pulse width modulation based on the interference frequency.

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