Protection circuit and communication equipment

Abstract

The utility model relates to the technical field of electronic circuits, and discloses a protection circuit and communication equipment, and the protection circuit comprises a transmission module and a control module. The input end of the transmission module is used for receiving an electric signal, and the transmission module is used for transmitting the electric signal from the input end to the output end in a conducting state; the control module comprises a control unit and a switch unit; the control unit comprises a voltage stabilizing tube; the anode of the voltage-regulator tube is connected with the first end of the switch unit, the cathode of the voltage-regulator tube is connected with the output end of the transmission module, the second end of the switch unit is connected with the control end of the transmission module and a voltage source, and the third end of the switch unit is grounded; when the voltage-regulator tube is reversely broken down, the switch unit is switched to the conducting state, and the transmission module is switched to the cut-off state from the conducting state. The protection circuit can effectively protect the communication chip when abnormal high voltage occurs.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technologies, and particularly to a protection circuit and a communication device. Background Art

[0002] Communication circuits generally use transient voltage suppressor diodes (TVS), discharge tubes, etc. to absorb high-voltage energy, so as to achieve the purpose of protecting the circuit.

[0003] During the use of electronic products, when the signal line is connected wrongly or the signal line is short-circuited with the power supply, an abnormal high voltage will occur, resulting in excessive absorbed energy, which will cause the TVS tube to burn out, and even cause the printed circuit board (PCB) to fail or be scrapped. Utility Model Content

[0004] In view of this, embodiments of this application provide a protection circuit and a communication device, which can effectively solve the problem that an abnormal high voltage may cause the PCB to fail or even be scrapped, etc.

[0005] In a first aspect, an embodiment of this application provides a protection circuit, including a transmission module and a control module;

[0006] The input end of the transmission module is used to receive an electrical signal, and the transmission module is used to transmit the electrical signal from the input end to the output end when in a conducting state;

[0007] The control module includes a control unit and a switch unit; the control unit includes a voltage stabilizing tube; the anode of the voltage stabilizing tube is connected to the first end of the switch unit, the cathode of the voltage stabilizing tube is connected to the output end of the transmission module, the second end of the switch unit is connected to the control end of the transmission module and a voltage source, and the third end of the switch unit is grounded;

[0008] When the voltage stabilizing tube breaks down reversely, the switch unit switches to a conducting state, and the transmission module switches from a conducting state to a cut-off state.

[0009] In some embodiments, the control module further includes a first resistor; the first end of the first resistor is connected to a voltage source, and the second end of the first resistor is connected to the control end of the transmission module and the second end of the switch unit.

[0010] In some embodiments, the control module further includes a second resistor and a third resistor;

[0011] The first end of the second resistor is connected to the first end of the switch unit, the second end of the second resistor is connected to the third end of the switch unit, the first end of the third resistor is connected to the first end of the switch unit, and the second end of the third resistor is connected to the anode of the voltage stabilizing tube.

[0012] In some embodiments, the control module further includes a fourth resistor and a filter capacitor;

[0013] The first end of the fourth resistor is connected to the anode of the voltage stabilizing diode, and the second end of the fourth resistor is grounded;

[0014] The first end of the filter capacitor is connected to the anode of the voltage stabilizing diode, and the second end of the filter capacitor is grounded.

[0015] In some embodiments, the switching unit includes a triode. The collector of the triode serves as the second end of the switching unit, the base of the triode serves as the first end of the switching unit, and the emitter of the triode serves as the third end of the switching unit.

[0016] In some embodiments, the transmission module includes a switching device, and the switching device includes at least one switching branch; when the switching branch is in a conducting state, the electrical signal is transmitted from one end of the switching branch to the other end.

[0017] In some embodiments, each switching branch includes a MOS transistor. The gate of the MOS transistor is connected to the control end of the transmission module, the source of the MOS transistor is connected to the input end of the transmission module, and the drain of the MOS transistor is connected to the output end of the transmission module.

[0018] In some embodiments, the transmission module includes a first switching device and a second switching device arranged in series. The first switching device includes at least one switching branch, the second switching device includes at least one switching branch, and the number of switching branches of the first switching device is the same as that of the second switching device;

[0019] Each switching branch of the first switching device is respectively connected in series with each switching branch of the second switching device to form a transmission branch of the transmission module.

[0020] In some embodiments, each switching branch of the first switching device includes a first MOS transistor, and each switching branch of the second switching device includes a second MOS transistor; the gate of the first MOS transistor is connected to the gate of the second MOS transistor, the source of the first MOS transistor is connected to the source of the second MOS transistor, the drain of the first MOS transistor is connected to the input end of the transmission module, and the drain of the second MOS transistor is connected to the output end of the transmission module.

[0021] In a second aspect, an embodiment of the present application provides a communication device, which includes a communication chip and the above protection circuit. The first end of the protection circuit is connected to the communication chip, and the second end of the protection circuit is connected to the communication port; an electrical signal is transmitted between the communication chip and the communication port, and the protection circuit is used to control the transmission or cut-off of the electrical signal.

[0022] The embodiments of the present application have the following beneficial effects:

[0023] When the communication is normal in the protection circuit of the present application, the control end of the transmission module is at a high level, and the transmission module is in a conducting state. The transmission module transmits the electrical signal from the input end of the transmission module to the output end; when an abnormal high voltage occurs at the output end of the transmission module, that is, the voltage at the output end suddenly becomes higher than the upper limit of the normal voltage range, the voltage stabilizing diode of the control unit is reversely broken down under the influence of the high voltage. Then, the voltage at the control end of the switch unit becomes high level, making the control switch unit conduct. Since the third end of the switch unit is grounded, under the conduction effect of the switch unit, the voltage at the control end of the transmission module is pulled down from high level to low level. At this time, the transmission module switches from the conducting state to the cut-off state and can no longer transmit the electrical signal from the input end to the output end, that is, it has a cut-off effect on the conduction of the electrical signal. Moreover, the cut-off state of the transmission module prevents the abnormal high voltage at the output end from affecting the communication chip at the input end of the transmission module and the electrical components in the transmission module in reverse, thus achieving a good protection effect and ensuring the safety and reliability of the printed circuit board. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 Shows the schematic diagram of the principle structure of the protection circuit in the embodiment of the present application;

[0026] Figure 2 Shows the first connection schematic diagram of the protection circuit in the embodiment of the present application;

[0027] Figure 3 Shows the second connection schematic diagram of the protection circuit in the embodiment of the present application;

[0028] Figure 4 Shows an application schematic diagram of the protection circuit in the embodiment of the present application.

[0029] Description of the main component numbers:

[0030] 10 - Transmission module; 20 - Control module; 21 - Switch unit; 22 - Control unit. Detailed implementation manners

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0032] Generally, the components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0033] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are only intended to represent specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0034] Unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as those commonly understood by those of ordinary skill in the art to which various embodiments of the present application belong. The terms (such as those defined in a commonly used dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in various embodiments of the present application.

[0035] The following will describe in detail some implementation manners of the present application with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] In view of the problem that when electronic products are in use currently, when the signal line is connected wrongly or the signal line is short - circuited with the power supply, an abnormal high voltage will occur, resulting in too high absorbed energy, and then causing the TVS tube to burn out, and even causing the printed circuit board (PCB board) to fail or be scrapped, thus damaging the communication circuit, the present application proposes a protection circuit and a communication device that can cut off the circuit under abnormal high voltage.

[0037] The protection circuit is described below in conjunction with some specific embodiments.

[0038] Figure 1 A schematic diagram of the principle structure of the protection circuit of the embodiment of the present application is shown. Exemplarily, the protection circuit includes a transmission module 10 and a control module 20; the input end of the transmission module 10 is used to receive an electrical signal, and the output end of the transmission module 10 is used to output an electrical signal; the transmission module 10 is used to transmit an electrical signal when in a conducting state; the control module 20 includes a control unit 22 and a switch unit 21; the control unit 22 includes a voltage regulator; the anode of the voltage regulator is connected to the control end of the switch unit 21, the cathode of the voltage regulator is connected to the output end of the transmission module 10, the input end of the switch unit 21 is respectively connected to the control end of the transmission module 10 and the voltage source, and the output end of the switch unit 21 is grounded; when the voltage regulator reversely breaks down, the switch unit 21 switches to the conducting state, and the transmission module 10 switches from the conducting state to the cut-off state.

[0039] In the present application, when the voltage at the output end of the transmission module 10 is suddenly higher than the upper limit of the normal voltage range of the output end of the transmission module 10, that is, when abnormally high voltage occurs, the voltage regulator connected to the output end of the transmission module 10 will be broken down by the high voltage, which can turn on the switch unit 21 and cut off the transmission module 10, thereby protecting the communication chip and the transmission module that output the electrical signal.

[0040] When the protection circuit of the present application communicates normally, the control end of the transmission module 10 is at a high level, and the transmission module 10 is in a conducting state at this time, and the transmission module 10 transmits the electrical signal; when the protection circuit detects that there is an abnormally high voltage at the output end of the transmission module 10, wherein the abnormally high voltage refers to a voltage suddenly higher than the upper limit of the normal voltage range of the output end of the transmission module 10; the voltage regulator of the control unit 22 reversely breaks down, and the control end voltage of the switch unit 21 becomes a high level, and the switch unit 21 is turned on, so that the voltage at the input end of the switch unit 21 is pulled down, and at the same time, the voltage at the control end of the transmission module 10 is pulled down from a high level to a low level, and the transmission module 10 switches from the conducting state to the cut-off state, and no longer transmits the electrical signal, thereby protecting the communication chip that outputs the electrical signal.

[0041] In one embodiment of the present application, the transmission module 10 includes a switching device, the switching device includes at least one switching branch; the switching branch includes a MOS tube, the gate of the MOS tube is connected to the control end of the transmission module 10, the source of the MOS tube is connected to the input end of the transmission module 10, and the drain of the MOS tube is connected to the output end of the transmission module 10.

[0042] Specifically, Figure 2As shown, the transmission module 10 includes a switching device Q2. The switching device Q2 includes two switching branches. Each switching branch includes a MOS transistor. The gate G(1,3) of the MOS transistor is connected to the control end of the transmission module 10. The source S(2,5) of the MOS transistor is connected to the input end (INA, INB) of the transmission module 10. The drain D(4,6) of the MOS transistor is connected to the output end (OUTA, OUTB) of the transmission module 10. Based on the two MOS transistors, the two switching branches form two transmission branches of the transmission module 10.

[0043] In the example of this application, the switching device includes two switching branches. As other embodiments, it may also include one or more than two, as long as the transmission requirements of the electrical signal are met.

[0044] The MOS transistor in the embodiment of this application includes a body diode and has unidirectional conductivity. There may still be an output after cut-off protection, that is, it may affect the protection. Therefore, in this application, the same MOS transistors are connected in series in reverse. That is, in another embodiment of this application, the transmission module 10 includes a first switching device and a second switching device arranged in series. Among them, the first switching device includes at least one switching branch, and the second switching device includes at least one switching branch. The number of switching branches of the first switching device is the same as that of the second switching device; the switching branches of the first switching device and the switching branches of the second switching device are connected in series to form the transmission branches of the transmission module 10.

[0045] For example, as Figure 3 shown, the first switching device Q2-1 includes two switching branches. Each switching branch includes a first MOS transistor, that is, the first switching device Q2-1 includes two first MOS transistors; the second switching device Q2-2 includes two switching branches. Each switching branch includes two second MOS transistors, that is, the second switching device Q2-2 includes two second MOS transistors; the gate G(1,3) of the first MOS transistor is connected to the gate G(1,3) of the second MOS transistor, the source S(5,2) of the first MOS transistor is connected to the source S(5,2) of the second MOS transistor, the drain D(6,4) of the first MOS transistor is connected to the input end (INA, INB) of the transmission module 10, and the drain D(6,4) of the second MOS transistor is connected to the output end (OUTA, OUTB) of the transmission module 10. That is, by connecting the first MOS transistor (1,5,6) and the second MOS transistor (1,5,6) in series and connecting the first MOS transistor (2,3,4) and the second MOS transistor (2,3,4) in series, the two switching branches of the first switching device and the two switching branches of the second switching device are connected in series in reverse, thereby forming two transmission branches of the transmission module 10.

[0046] Taking one of the transmission branches as an example to introduce its working process: During normal operation, the electrical signal is transmitted bidirectionally between the input and output ends of the transmission module 10 through the first MOS transistor and the second MOS transistor. When a high voltage occurs at the output end of the transmission module 10, the zener diode of the control unit 22 is reversely broken down, and the switch unit 21 is turned on, thereby pulling down the level of the control end of the transmission module 10. The first MOS transistor and the second MOS transistor in the transmission branch are turned off. Due to the unidirectional conduction of the body diode in the first MOS transistor or the second MOS transistor, the electrical signal cannot be transmitted from the first MOS transistor to the second MOS transistor, that is, the transmission module 10 cannot transmit the electrical signal, thereby protecting the communication chip.

[0047] In the embodiment of the present application, the control module 20 further includes a first resistor R1; the first end of the first resistor R1 is connected to the voltage source VCC, and the second end of the first resistor R1 is connected to the control end of the transmission module 10 and the input end of the switch unit 21. The first resistor R1 is used in the present application to prevent the high voltage from being directly connected to the control end of the transmission module or the input end of the switch unit 21, effectively preventing the direct connection from being burned out, thereby playing a voltage stabilizing role.

[0048] The control module 20 of the present application connects the voltage source VCC to the control end of the transmission module 10 through the first resistor R1 to provide a control voltage for the transmission module 10.

[0049] In the embodiment of the present application, the control module 20 further includes a second resistor R2 and a third resistor R3;

[0050] The first end of the second resistor R2 is connected to the control end of the switch unit 21, the second end of the second resistor R2 is connected to the output end of the switch unit 21, the first end of the third resistor R3 is connected to the control end of the switch unit 21, and the second end of the third resistor R3 is connected to the anode of the zener diode (ZD1, ZD2).

[0051] In the embodiment of the present application, the switch unit 21 includes a triode Q1. The collector of the triode Q1 is used as the input end of the switch unit 21, the base of the triode Q1 is used as the control end of the switch unit 21, and the source of the triode Q1 is used as the output end of the switch unit 21.

[0052] In the embodiment of the present application, the control module 20 further includes a fourth resistor R4 and a filter capacitor C1; the first end of the fourth resistor R4 is connected to the anode of the zener diode (ZD1, ZD2), and the second end of the fourth resistor R4 is grounded; the first end of the filter capacitor C1 is connected to the anode of the zener diode (ZD1, ZD2), and the second end of the filter capacitor C1 is grounded. The present application filters the signal through the filter unit formed by the fourth resistor R4 and the filter capacitor C1 to improve the reliability of the signal.

[0053] The embodiment of the present application also proposes a communication device. Exemplarily, such asFigure 4 As shown, the communication device includes a communication chip and a protection circuit. The first end of the protection circuit is connected to the communication chip, and the second end of the protection circuit is connected to the communication port. An electrical signal is transmitted between the communication chip and the communication port, and the protection circuit is used to control the transmission or cut-off of the electrical signal.

[0054] The communication device of the present application can perform communication transmission in ways such as RS485 and RS232. The communication chip is used to transmit various electrical signals, such as voltage signals, current signals, etc. The communication interface is used to receive electrical signals. For example, the communication interface is the receiving end of various processing circuits / chips such as a detection circuit and a comparison circuit.

[0055] It can be understood that the optional items in the above embodiments are equally applicable to this embodiment, so they will not be described repeatedly here.

[0056] In several embodiments provided by the present application, it should be understood that the disclosed circuit can also be implemented in other ways. The circuit embodiments described above are merely illustrative. For example, the connection schematic diagram and the structural diagram in the drawings show the applications according to multiple embodiments of the present application.

[0057] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application.

Claims

1. A protection circuit, characterized in that, It includes a transmission module and a control module; The transmission module is used to receive an electrical signal and transmit the electrical signal when the transmission module is in a conducting state; The control module includes a control unit and a switching unit; the control unit includes a zener diode; the anode of the zener diode is connected to the first end of the switching unit, the cathode of the zener diode is connected to the output end of the transmission module, the output end of the switching unit is connected to the control end of the transmission module and a voltage source, and the third end of the switching unit is grounded; When the zener diode is reversely broken down, the switching unit switches to a conducting state, and the transmission module switches from a conducting state to a cut-off state.

2. The protection circuit according to claim 1, wherein The control module further includes a first resistor; the first end of the first resistor is connected to a voltage source, and the second end of the first resistor is connected to the control end of the transmission module and the second end of the switching unit.

3. The protection circuit according to claim 2, characterized in that, The control module further includes a second resistor and a third resistor; The first end of the second resistor is connected to the first end of the switching unit, the second end of the second resistor is connected to the third end of the switching unit, the first end of the third resistor is connected to the first end of the switching unit, and the second end of the third resistor is connected to the anode of the zener diode.

4. The protection circuit according to claim 3, characterized in that, The control module further includes a fourth resistor and a filter capacitor; The first end of the fourth resistor is connected to the anode of the zener diode, and the second end of the fourth resistor is grounded; The first end of the filter capacitor is connected to the anode of the zener diode, and the second end of the filter capacitor is grounded.

5. The protection circuit according to claim 1, wherein The switching unit includes a triode, the collector of the triode serves as the second end of the switching unit, the base of the triode serves as the first end of the switching unit, and the emitter of the triode serves as the third end of the switching unit.

6. The protection circuit according to claim 1, characterized in that, The transmission module includes a switching device, and the switching device includes at least one switching branch; when the switching branch is in a conducting state, the electrical signal is transmitted from one end of the switching branch to the other end.

7. The protection circuit according to claim 6, wherein Each switching branch includes a MOS transistor, the gate of the MOS transistor is connected to the control end of the transmission module, the source of the MOS transistor is connected to the input end of the transmission module, and the drain of the MOS transistor is connected to the output end of the transmission module.

8. The protection circuit according to claim 1, characterized in that The transmission module includes a first switching device and a second switching device connected in series, the first switching device includes at least one switching branch, the second switching device includes at least one switching branch, and the number of switching branches of the first switching device and the second switching device is the same; Each switching branch of the first switching device is respectively connected in series with each switching branch of the second switching device to form a transmission branch of the transmission module.

9. The protection circuit according to claim 8, wherein Each switching branch of the first switching device includes a first MOS transistor, and each switching branch of the second switching device includes a second MOS transistor; the gate of the first MOS transistor is connected to the gate of the second MOS transistor, the source of the first MOS transistor is connected to the source of the second MOS transistor, the drain of the first MOS transistor is connected to the input end of the transmission module, and the drain of the second MOS transistor is connected to the output end of the transmission module.

10. A communication device, characterized in that, The communication device includes a communication chip and the protection circuit according to any one of claims 1-9. A first end of the protection circuit is connected to the communication chip, and a second end of the protection circuit is connected to a communication port. An electrical signal is transmitted between the communication chip and the communication port, and the protection circuit is configured to control the transmission or cutoff of the electrical signal.

Images