Input / output protection circuit and circuit protection device
The signal electrical isolation is achieved through the optocoupler, which solves the isolation and protection problem between the main circuit and the external equipment in the circuit design, reduces the risk of damage and reduces the cost.
Patent Information
- Application Number
- CN202422260711.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-14
AI Technical Summary
In the existing circuit design, the main circuit and external equipment lack isolation protection, which is prone to burnout, and the cost of increasing the integrated IC optocoupling method is high.
Optocouplers are used to achieve electrical isolation of signals, and through isolation elements, switching elements, input protection units and output protection units, voltage and current are limited to achieve signal isolation transmission.
It effectively solves the problem of isolation and protection between the main circuit and external equipment, reduces the risk of circuit damage, and is low-cost, and is suitable for various IO protection circuit designs.
Smart Images
Figure CN223079752U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of circuits, and particularly relates to an input / output protection circuit and a circuit protection device. Background Art
[0002] At present, most circuits are designed by directly inputting / outputting through the IO of the CPU or MCU without isolation protection, which is very easy to burn out the circuit. Although there is an electrostatic ESD protection function inside the chip IO pin, it is impossible to achieve the isolation protection between the motherboard circuit and the peripheral circuit. However, by adding an integrated IC optocoupler to design the circuit, the cost will be much higher, increasing the manufacturing cost of the product. Content of the Utility Model
[0003] The purpose of the utility model is to provide an input / output protection circuit and a circuit protection device for the deficiencies of the existing technology, aiming to achieve the isolation protection of the circuit.
[0004] The utility model realizes the above purpose through the following technical solutions: An input / output protection circuit includes:
[0005] An isolation element, having an input end and an output end, for realizing the electrical isolation of the input signal and the output signal through an opto-coupling method;
[0006] A switching element, connected to the input end of the isolation element, for controlling the working state of the isolation element according to the control signal of the IO port. Specifically, the switching element is used to receive the control signal of the IO port to switch the isolation element between conduction and cut-off;
[0007] An input protection unit, for limiting the voltage or current of the input signal to prevent the input signal from damaging the circuit; and
[0008] An output protection unit, connected to the output end of the isolation element, for performing current-limiting protection on the output signal and providing a signal output port isolated by the isolation element.
[0009] As a further scheme of the utility model: The isolation element includes an opto-coupler. The input end of the isolation element is connected to a photosensitive device through a light-emitting diode (LED), and the output end of the isolation element realizes the opto-electric conversion of the signal through the photosensitive device.
[0010] As a further scheme of the utility model: The switching element includes a triode Q1. The collector of the triode Q1 is connected to the input end of the opto-coupler, the emitter of the triode Q1 is grounded, and the base of the triode Q1 is connected to the input end IO_CTRL for receiving the control signal of the IO port through a resistor R8.
[0011] As a further solution of the present utility model: the input protection unit includes a diode D1, a first resistor R1 and a second resistor R2. The negative electrode of the diode D1 is connected to the input signal terminal IO1, and the positive electrode is grounded. The first resistor R1 and the second resistor R2 are connected to the negative electrode of the diode D1 and are used to limit the magnitude of the current entering the input end of the optocoupler.
[0012] As a further solution of the present utility model: the input protection unit further includes a resistor R3. One end of the resistor R3 is connected to the negative electrode of the diode D1, and the other end is connected to the input end of the optocoupler. The resistor R3 is used to adjust the magnitude of the current flowing into the light-emitting diode (LED) inside the optocoupler to control the light-emitting intensity of the light-emitting diode (LED).
[0013] As a further solution of the present utility model: the output protection unit includes a resistor R5 and a resistor R6. The resistor R5 is connected to an output end of the optocoupler and serves as an open-drain output; the resistor R6 is connected to the other output end of the optocoupler and serves as a GPIO output.
[0014] As a further solution of the present utility model: the output protection unit further includes a resistor R9. One end of the resistor R9 is connected to the third pin of the optocoupler, and the other end is grounded. The resistor R9 is used to limit the current flowing to the ground.
[0015] As a further solution of the present utility model: the input-output protection circuit further includes a power supply module for providing a working voltage for the isolation element and the switching element.
[0016] As a further solution of the present utility model: the power supply module includes a resistor R4. The resistor R4 is connected between the fourth pin of the optocoupler and the power supply and is used to provide a stable working voltage.
[0017] As a further solution of the present utility model: an input-output protection circuit includes an optocoupler, a diode D1, a triode Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9;
[0018] The common end of the seventh resistor R7 and the eighth resistor R8 is electrically connected to the base of the triode Q1, and the other end of the seventh resistor R7 is grounded; the emitter of the triode Q1 is grounded; the collector of the triode Q1 is electrically connected to the second pin of the optocoupler; the control signal is input from the other end of the eighth resistor R8;
[0019] The common terminal of the first resistor R1, the second resistor R2, and the cathode of the diode D1 is electrically connected to one end of the third resistor R3. The anode of the diode D1 is grounded, and the other end of the third resistor R3 is electrically connected to the first pin of the optocoupler; the other end of the first resistor R1 is connected to the power supply;
[0020] The common terminal of the fourth resistor R4 and the fifth resistor R5 is electrically connected to the fourth pin of the optocoupler; the other end of the fourth resistor R4 is connected to the power supply; the other end of the fifth resistor R5 is used as an open-drain output;
[0021] The common terminal of the sixth resistor R6 and the ninth resistor R9 is electrically connected to the third pin of the optocoupler, and the other end of the ninth resistor R9 is grounded; the other end of the seventh resistor R6 outputs the GPIO2 signal.
[0022] As a further solution of the present invention: The control signal is input from the other end of the eighth resistor R8 as the input terminal to control the conduction and cutoff of the triode Q1; when the triode Q1 is cutoff, the cathode of the LED inside the optocoupler is at a high level, and the LED inside the optocoupler is cutoff and does not emit light;
[0023] By adjusting the resistance value of the third resistor R3, the intensity of the light emitted by the LED inside the optocoupler is adjusted. By controlling the intensity of the light, the conduction and cutoff of the triode Q1 inside the optocoupler are controlled, thereby controlling the open-drain output state of the fourth pin of the optocoupler.
[0024] The present invention also provides another technical solution: A circuit protection device includes the input-output protection circuit as described in any one of the foregoing.
[0025] Working principle of the input-output protection circuit:
[0026] When the input signal terminal IO1 receives an input signal, the input protection unit (resistors R1, R2, and diode D1) will protect the input signal and limit excessive voltage or current;
[0027] The control signal of the IO port enters from the input terminal IO_CTRL, passes through the resistor R8 and enters the base of the triode Q1 to determine the switching state of the triode Q1. If the control signal is at a high level, the triode Q1 conducts, and the light-emitting diode (LED) inside the optocoupler will emit light;
[0028] When the LED emits light, the output terminal of the optocoupler will generate an electrical signal corresponding to the input terminal. This signal is output to an external device after passing through the output protection unit (resistors R5 and R6);
[0029] In this way, through the transmission of optoelectronic signals, the input signal realizes isolated transmission from the main circuit to the external circuit, avoiding direct contact of current and protecting the safety of the main circuit.
[0030] Advantages of the present utility model:
[0031] The present utility model realizes isolation of the optocoupler through the input-output protection circuit, effectively solving the problem of lack of isolation protection between the main circuit and external devices in the existing circuit design, and further enhancing the anti-interference ability of the circuit and reducing the risk of circuit damage through the input protection unit and the output protection unit. In addition, the present utility model is low in cost and easy to implement, and has a wide application prospect in various circuit designs requiring IO protection. Description of the drawings
[0032] Figure 1 It is a circuit diagram of the input-output protection circuit of the present utility model. Detailed implementation manners
[0033] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model. It can be understood that the drawings are only for reference and description, and are not used to limit the present invention. The connection relationships shown in the drawings are only for clear description and do not limit the connection manner.
[0034] In order to make the above objects, features and advantages of the present application more obvious and understandable, the following detailed description of the specific implementation manners of the present application will be made in conjunction with the drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.
[0035] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present application.
[0036] In addition, if there is a term "and / or", "and / or" is merely a correlative relationship describing related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the related objects before and after. If there are terms such as "first" and "second", these terms are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if there is a term "plurality", the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0037] In the present application, unless otherwise clearly specified and limited, if there are terms such as "mounted", "connected", "coupled", "fixed", etc., these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0038] In the present application, unless otherwise clearly specified and limited, if there is a description such as a first feature being "on" or "under" a second feature, etc., the meaning can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath", and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.
[0039] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If present, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.
[0040] In the related art, at present, most circuits are designed by directly inputting / outputting through the IO of the CPU or MCU without isolation protection, and it is very easy to burn out the circuit. Although there is an electrostatic ESD protection function inside the chip IO pin, it is impossible to achieve the isolation protection between the motherboard circuit and the peripheral circuit. However, by adding an integrated IC optocoupler to design the circuit, the cost will be much higher, increasing the manufacturing cost of the product.
[0041] Therefore, the embodiments of this application provide an input / output protection circuit that can achieve isolation protection for the circuit.
[0042] As Figure 1 shown, in the embodiments of the present utility model, an input / output protection circuit is provided, including: an isolation element, a switching element, an input protection unit, and an output protection unit. Among them:
[0043] The isolation element has an input end and an output end, and is used to achieve electrical isolation between the input signal and the output signal through an opto-coupling method;
[0044] The switching element is connected to the input end of the isolation element, and is used to control the working state of the isolation element according to the control signal of the IO port. Specifically, the switching element is used to receive the control signal of the IO port to switch the conduction and cut-off of the isolation element;
[0045] The input protection unit is used to limit the voltage or current of the input signal to prevent the input signal from damaging the circuit;
[0046] The output protection unit is connected to the output end of the isolation element, and is used to perform current limiting protection on the output signal and provide a signal output port isolated by the isolation element. Specifically, the isolated signal output port refers to the signal port that is transmitted from the output end of the circuit to the external device after the electrical isolation process of the opto-coupler. Simply put, it is the signal output part after the opto-coupler completes electrical isolation, and is used to transmit the information in the circuit to other circuits or devices.
[0047] Working principle of the input / output protection circuit:
[0048] When the input signal terminal IO1 receives an input signal, the input protection unit (resistors R1, R2, and diode D1) protects the input signal and limits excessive voltage or current;
[0049] The control signal of the IO port enters from the input terminal IO_CTRL, passes through resistor R8 and enters the base of transistor Q1 to determine the switching state of transistor Q1. If the control signal is high level, transistor Q1 conducts, and the light-emitting diode (LED) inside the optocoupler will emit light;
[0050] When the LED emits light, the output terminal of the optocoupler generates an electrical signal corresponding to the input terminal. After this signal passes through the output protection unit (resistors R5 and R6), it is output to external devices;
[0051] In this way, through the transmission of optical signals, the input signal realizes isolated transmission from the main circuit to the external circuit, avoiding direct contact of current and protecting the safety of the main circuit.
[0052] The present utility model realizes optocoupler isolation through an input-output protection circuit, effectively solves the problem of lack of isolation protection between the main circuit and external devices in the existing circuit design, further enhances the anti-interference ability of the circuit through the input protection unit and the output protection unit, and reduces the risk of circuit damage. In addition, the present utility model has low cost and is easy to implement, and has a wide application prospect in various circuit designs that require IO protection.
[0053] In one embodiment, the isolation element includes an optocoupler. The input terminal of the isolation element is connected to a photosensitive device through a light-emitting diode (LED), and the output terminal of the isolation element realizes photoelectric conversion of signals through the photosensitive device.
[0054] In another embodiment, the switching element includes a transistor Q1. The collector of transistor Q1 is connected to the input terminal of the optocoupler, the emitter of transistor Q1 is grounded, and the base of transistor Q1 is connected to the input terminal IO_CTRL for receiving the control signal of the IO port through resistor R8.
[0055] In yet another embodiment, the input protection unit includes diode D1, first resistor R1, and second resistor R2. The negative pole of diode D1 is connected to the input signal terminal IO1, the positive pole is grounded, one end of first resistor R1 is connected to the input signal terminal, the other end is connected to the power supply VCC3V3 - SYS, and one end of second resistor R2 is connected to the collector of transistor Q1, and the other end is connected to the negative pole of diode D1 to limit the magnitude of the current entering the input terminal of the optocoupler.
[0056] In yet another embodiment, the input protection unit further includes a resistor R3. One end of the resistor R3 is connected to the negative electrode of the diode D1, and the other end is connected to the input end of the optocoupler. The resistor R3 is used to adjust the magnitude of the current flowing into the light-emitting diode (LED) inside the optocoupler to control the light-emitting intensity of the light-emitting diode (LED).
[0057] In another embodiment, the output protection unit includes a resistor R5 and a resistor R6. The resistor R5 is connected to an output end of the optocoupler and serves as an open-drain output; the resistor R6 is connected to the other output end of the optocoupler and serves as a GPIO output. Specifically, the output end of the optocoupler has an open-drain characteristic. The resistor R5 is connected to the 4th pin of the optocoupler, and its function is to pull-up the resistor, raising the floating state of the output end of the optocoupler to help generate the correct signal level and ensure the correct transmission of the signal to GPIO1. The resistor R6 is connected to the 3rd pin of the optocoupler and serves as a standard GPIO output signal for controlling the level of GPIO2.
[0058] In another embodiment, the output protection unit further includes a resistor R9. The resistor R9 is connected to the third pin of the optocoupler, and the other end is grounded. The resistor R9 is used to limit the current flowing to the ground.
[0059] In another embodiment, the input-output protection circuit further includes a power supply module for providing a working voltage for the isolation element and the switching element.
[0060] In another embodiment, the power supply module includes a resistor R4. The resistor R4 is connected between the fourth pin of the optocoupler and the power supply for providing a stable working voltage.
[0061] A circuit protection device includes the input-output protection circuit according to any one of the present solutions.
[0062] The working principle of optocoupler isolation protection:
[0063] Optocoupler isolation protection is a technology that achieves electrical isolation and signal transmission through an optocoupler (photoelectric coupler). The optocoupler mainly consists of a light-emitting diode (LED) and a photosensitive element (such as a photosensitive transistor or a photosensitive diode). They are encapsulated in a housing and transmit information through optical signals. The working principle of the optocoupler is as follows:
[0064] 1. The IO1 or 3.3V input signal, IO_CTRL controls and drives the LED: At the input end, the electrical signal drives the LED to emit light. The parameter changes of the input signals of the resistors R1, R2, R3 and the change of IO_CTRL will affect the light intensity emitted by the LED.
[0065] 2. Optical signal transmission: The light emitted by the LED passes through the transparent medium of the optocoupler and reaches the photosensitive element inside the package.
[0066] 3. Photoelectric conversion: After the photosensitive element (such as a photosensitive transistor) receives the optical signal, it generates an electrical signal proportional to the light intensity. This process realizes the photoelectric conversion of the signal.
[0067] 4. Output signal: The photosensitive element converts the optical signal into an electrical signal and outputs it to the external circuit. GPIO1 is used as an open-drain output, with the change of high and low levels to control the external circuit; GPIO2 can be used as a voltage output, and the output signal can be a voltage or current signal, depending on the hardware parameters set by the circuit.
[0068] In this way, the optocoupler realizes electrical isolation between the input and the output. This isolation can prevent high voltage or noise from being conducted from the input end to the output end, protecting sensitive electronic devices from electrical interference or damage. In addition, the electrical isolation ability of the optocoupler also makes them very suitable for use in circuits that need to isolate different potentials, such as power management, signal conditioning, and communication interfaces.
[0069] Such as Figure 1 As shown, in the embodiment of the present invention, an input-output protection circuit is further provided, including an optocoupler, a diode D1, a triode Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9.
[0070] The common end of the seventh resistor R7 and the eighth resistor R8 is electrically connected to the base of the triode Q1, and the other end of the seventh resistor R7 is grounded; the emitter of the triode Q1 is grounded; the collector of the triode Q1 is electrically connected to the second pin of the optocoupler; the control signal is input from the other end of the eighth resistor R8 as the input end.
[0071] The common end of the first resistor R1, the second resistor R2, and the negative electrode of the diode D1 is electrically connected to one end of the third resistor R3, the positive electrode of the diode D1 is grounded, the other end of the third resistor R3 is electrically connected to the first pin of the optocoupler, and the other end of the first resistor R1 is connected to the power supply.
[0072] In this embodiment, the 3.3V power supply supplies power to the optocoupler through the first resistor R1 and the third resistor R3, causing the LED inside the optocoupler to emit light and trigger the working state.
[0073] The common end of the fourth resistor R4 and the fifth resistor R5 is electrically connected to the fourth pin of the optocoupler, the other end of the fourth resistor R4 is connected to the power supply, and the other end of the fifth resistor R5 is used as an open-drain output.
[0074] The common terminal of the seventh resistor R6 and the ninth resistor R9 is electrically connected to the third pin of the optocoupler, and the other end of the ninth resistor R9 is grounded; the other end of the seventh resistor R6 outputs the GPIO2 signal.
[0075] The control signal is input from the other end of the eighth resistor R8 as the input terminal to control the conduction and cut-off of the triode Q1. Specifically, when the control signal is at a high level, the emitter of the triode Q1 conducts, and at this time, the triode Q1 conducts. At this time, the negative electrode of the LED inside the optocoupler is at a low level, and the LED inside the optocoupler emits light.
[0076] When the control signal is at a low level, the emitter of the triode Q1 is cut off, and at this time, the triode Q1 is turned off. When the triode Q1 is cut off, the negative electrode of the LED inside the optocoupler is at a high level, and the LED inside the optocoupler is cut off and does not emit light.
[0077] By adjusting the resistance value of the third resistor R3, the intensity of the light emitted by the LED inside the optocoupler is adjusted. By controlling the intensity of the light, the conduction and cut-off of the triode Q1 inside the optocoupler are controlled, thereby controlling the open-drain output state of the fourth pin of the optocoupler.
[0078] When the resistance of the third resistor R3 increases, the intensity of the light emitted by the LED inside the optocoupler decreases, and the triode Q1 inside the optocoupler is cut off. On the contrary, when the resistance of the third resistor R3 decreases, the intensity of the light emitted by the LED inside the optocoupler increases, and the triode Q1 inside the optocoupler conducts.
[0079] In the description and claims of this application, the words "comprising / including" and the words "having / including" and their variants are used to specify the presence of the stated features, values, steps or components, but do not exclude the presence or addition of one or more other features, values, steps, components or combinations thereof.
[0080] Some features of the present invention are described separately in different embodiments for clarity. However, these features can also be described in combination in a single embodiment. On the contrary, some features of the present invention are described only in a single embodiment for brevity. However, these features can also be described separately or in any suitable combination in different embodiments.
[0081] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.
Claims
1. An input-output protection circuit, characterized in that, Comprising: An isolation element, having an input end and an output end, for electrically isolating an input signal and an output signal through an opto - coupling manner; A switching element, connected to the input end of the isolation element, for controlling the working state of the isolation element; An input protection unit, for limiting the voltage or current of the input signal; And An output protection unit, connected to the output end of the isolation element, for performing current - limiting protection on the output signal and providing a signal output port isolated by the isolation element.
2. The input / output protection circuit according to claim 1, characterized in that The isolation element includes an opto - coupler. The input end of the isolation element is connected to a photosensitive device through a light - emitting diode, and the output end of the isolation element realizes photoelectric conversion of the signal through the photosensitive device.
3. The input-output protection circuit according to claim 2, wherein The switching element includes a triode Q1. The collector of the triode Q1 is connected to the input end of the opto - coupler. The emitter of the triode Q1 is grounded. The base of the triode Q1 is connected to the input end IO_CTRL for receiving a control signal of an IO port through a resistor R8.
4. The input-output protection circuit according to claim 3, wherein The input protection unit includes a diode D1, a first resistor R1, and a second resistor R2. The negative electrode of the diode D1 is connected to the input signal terminal IO1, and the positive electrode is grounded. The first resistor R1 and the second resistor R2 are connected to the negative electrode of the diode D1 and are used for limiting the magnitude of the current entering the input end of the opto - coupler.
5. The input-output protection circuit according to claim 4, wherein The input protection unit further includes a resistor R3. One end of the resistor R3 is connected to the negative electrode of the diode D1, and the other end is connected to the input end of the opto - coupler. The resistor R3 is used for adjusting the magnitude of the current flowing into the light - emitting diode inside the opto - coupler to control the light - emitting intensity of the light - emitting diode.
6. The input-output protection circuit according to claim 5, wherein The output protection unit includes a resistor R5 and a resistor R6. The resistor R5 is connected to an output end of the opto - coupler and serves as an open - drain output; the resistor R6 is connected to the other output end of the opto - coupler and serves as a GPIO output.
7. The input / output protection circuit according to claim 6, characterized in that, The output protection unit further includes a resistor R9. The resistor R9 is connected to the third pin of the opto - coupler, and the other end is grounded. The resistor R9 is used for limiting the current flowing to the ground.
8. The input-output protection circuit according to claim 7, characterized in that This input - output protection circuit further includes a power supply module for providing a working voltage for the isolation element and the switching element.
9. The input-output protection circuit according to claim 8, wherein, The power supply module includes a resistor R4. The resistor R4 is connected between the fourth pin of the opto - coupler and the power supply and is used for providing a stable working voltage.
10. A circuit protection device, characterized in that, Including the input - output protection circuit according to any one of claims 1 - 9.