A surge protection method and a surge protection signal interface circuit

Abstract

This invention belongs to the field of electronic circuit technology and discloses a surge protection switch signal interface circuit and surge protection method, including a positive diode, a negative diode, a bypass switch circuit, and a signal isolation transmission circuit. The cathode of the positive diode and the bypass switch circuit are respectively connected to the signal input terminal. The bypass switch circuit is connected in parallel with the primary side of the signal isolation transmission circuit. The positive terminal of the bypass switch circuit is connected to the anode of the positive diode, and the negative terminal of the bypass switch circuit is connected to the anode of the negative diode. The cathode of the negative diode is connected to the reference ground of the signal input terminal. The secondary side of the signal isolation transmission circuit is the signal output terminal. This invention is compatible with both "ground / on" and "high / on" signal types. Different types of switch signals can use the same circuit structure, reducing the types of components and facilitating component selection. It also has surge protection functionality, avoids the use of TVS diodes, and has advantages such as high reliability, low cost, and small size.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit technology, and particularly relates to a surge protection switch signal interface circuit and surge protection method. Background Technology

[0002] Aerospace electronic and electrical equipment often uses "ground / on" or "high / on" type switching signals to exchange information with external devices or other devices in the system, transmitting commands or status information. Different switching signal types ("ground / on" or "high / on") employ different circuit structures. For lightning surge protection of interface circuits, transient voltage suppressor diodes (TVS) are often used, which are costly, and when high lightning protection requirements are needed, TVS are large in size, making selection difficult.

[0003] Based on the above analysis, the problems and defects of the existing technology are as follows: the lightning surge protection of the existing interface circuits often adopts transient suppression diodes, which are costly, and the TVS size is large when the lightning protection level requirement is high, making selection difficult. Summary of the Invention

[0004] To overcome the problems existing in related technologies, the present invention discloses an embodiment of a surge protection switch signal interface circuit and a surge protection method.

[0005] The technical solution of the present invention is as follows: A surge protection switch signal interface circuit includes: a positive terminal diode, a negative terminal diode, a bypass switch circuit, and a signal isolation transmission circuit;

[0006] The signal input terminal is connected to the cathode of the positive diode and the control terminal of the bypass switch circuit. The positive and negative terminals of the bypass switch circuit are connected in parallel with the primary side of the signal isolation transmission circuit. The positive terminal of the bypass switch circuit is connected to the anode of the positive diode, and the negative terminal of the bypass switch circuit is connected to the anode of the negative diode.

[0007] The cathode of the negative diode is connected to the reference ground of the signal input terminal;

[0008] The secondary side of the signal isolation transmission circuit is the signal output terminal, which transmits the signal to the relevant control circuit.

[0009] Furthermore, the signal isolation transmission circuit is equipped with an optocoupler OP1, which is connected to resistors R1, R2, and R4.

[0010] Furthermore, in the signal isolation transmission circuit, the primary anode of the optocoupler OP1 is connected to the 28V power supply through resistor R2, the secondary collector is connected to the control power supply Vcc through resistor R1, resistor R4 is connected in parallel with the primary light-emitting diode of OP1, and the secondary collector of optocoupler OP1 is the signal output pin.

[0011] Furthermore, the primary side of the signal isolation transmission circuit shares a common ground with the signal input terminal, and the secondary side references the control ground SGND.

[0012] The circuit includes a transistor Q1, resistors R3 and R5, and a Zener diode D2. Resistor R5 is connected in parallel between the base (B) and emitter (E) of transistor Q1. Resistor R3 is connected in series with the cathode of Zener diode D2. The anode of Zener diode D2 is connected to the base (B) of transistor Q1. The collector (C) of transistor Q1 is connected to the anode of the primary LED of optocoupler OP1 in the signal isolation circuit. The emitter (E) of transistor Q1 is connected to the cathode of the primary LED of optocoupler OP1.

[0013] Furthermore, the other end of the resistor R3 is connected to the cathode of the positive diode and the signal input terminal, and the anode of the positive diode is connected to the collector of Q1 and the anode of the primary-side light-emitting diode of OP1.

[0014] Furthermore, the emitter (E) of Q1 and the cathode of the primary-side LED of OP1 are connected to the anode of the negative-side LED, and the cathode of the negative-side LED is connected to the input signal reference ground.

[0015] Another objective of this invention is to provide a surge protection method for a surge protection switch signal interface circuit. Applied to the surge protection switch signal interface circuit, this method employs a high-voltage diode combined with a bypass switch to perform interface conversion for different types of switch signals, while eliminating the need for low-reliability surge suppression devices, thus achieving interface surge protection. Specifically, it includes:

[0016] When the input switch signal Signal is ground / open and grounded, the positive diode is turned on, and the primary side of the signal isolation transmission circuit is shorted to the input reference ground through the positive diode, so the input signal on the primary side of the signal isolation transmission circuit is low.

[0017] When the input switch signal Signal is high / on and high, the bypass switch circuit is closed, the primary side of the signal isolation transmission circuit is shorted to the input reference ground through the negative terminal diode, and the input signal on the primary side of the signal isolation transmission circuit is low.

[0018] Furthermore, the low-reliability surge suppression device is a transient voltage suppressor (TVS) or a varistor.

[0019] Furthermore, when the input switch signal Signal is open, the primary input signal of the signal isolation transmission circuit is high level;

[0020] When a positive or negative pulse surge occurs at the positive or negative terminal of the input signal, the surge voltage can be blocked by the two diodes at the positive and negative terminals. The surge current value that the bypass switch circuit can withstand is limited to a safe level by resistor R3.

[0021] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows: The surge protection switch signal interface circuit provided by this invention uses a high-voltage diode to achieve lightning surge protection of the interface, and is compatible with "ground / on" or "high / on" signal types, with high reliability, low cost and small size.

[0022] This invention is compatible with both "ground / on" and "high / on" signal types. Different types of switching signals can use the same circuit structure, reducing the types of components and facilitating component selection. It also has surge protection function, avoids the use of TVS diodes, and has the advantages of high reliability, low cost, and small size.

[0023] The technical solution of this invention uses a diode combined with a bypass switch to replace TVS to achieve interface surge protection, which can reduce the cost by 4-5 times. At the same time, it is compatible with different switch signal types, realizes the unification of interface circuits, and facilitates the implementation of three-dimensional design.

[0024] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the disclosure of the present invention. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0026] Figure 1 This is a structural block diagram of the surge protection switch signal interface circuit provided in an embodiment of the present invention;

[0027] Figure 2 This is a connection schematic diagram of the surge protection switch signal interface circuit provided in an embodiment of the present invention;

[0028] In the diagram: 1. Positive diode; 2. Negative diode; 3. Bypass switch circuit; 4. Signal isolation transmission circuit. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] The innovation of the surge protection switch signal interface circuit and surge protection method provided in this invention lies in the use of a high-voltage diode combined with a bypass switch. This allows for interface conversion of different types of switch signals without the need for high-cost surge suppression devices such as TVS (Transient Voltage Suppressors, also known as avalanche breakdown diodes, which are devices made using semiconductor technology that integrate single or multiple PN junctions) or low-reliability surge suppression devices such as varistors. This effectively achieves interface surge protection with low cost and high reliability.

[0031] Examples, such as Figure 1 As shown, the surge protection switch signal interface circuit provided in this embodiment of the invention includes a positive diode 1, a negative diode 2, a bypass switch circuit 3, and a signal isolation transmission circuit 4.

[0032] “Signal” is the input switch signal, which can be a “ground / on” type switch signal or a “high / on” type switch signal. It is connected to the cathode of the positive diode 1 and at the same time connected to the control terminal of the bypass switch circuit 3 to control the on and off of the bypass switch.

[0033] The positive and negative terminals of the bypass switch circuit 3 are connected in parallel with the primary side of the signal isolation transmission circuit 4. After parallel connection, the positive terminal is connected to the anode of the positive diode 1, and the negative terminal is connected to the anode of the negative diode 2.

[0034] The cathode of diode 2 is connected to the reference ground of the input signal;

[0035] The signal isolation transmission circuit 4 isolates and converts the primary-side input switching signal before outputting it to the relevant control circuit.

[0036] like Figure 2 As shown, diode D1 is the input signal blocking diode, corresponding to... Figure 1 Diode 1 is the positive terminal diode; Diode D3 is the input signal reference ground blocking diode, corresponding to... Figure 1 The negative terminal diode 2; the transistor Q1 (NPN), the Zener diode D2, the resistor R3, and the resistor R5 constitute the bypass switch circuit 3; the optocoupler OP1, the resistor R1, the resistor R2, and the resistor R4 constitute the signal isolation transmission circuit 4.

[0037] The working principle of this invention is:

[0038] The signal isolation transmission circuit 4, consisting of optocoupler OP1 and resistors R1, R2, and R4, is powered by 28V on its primary side and shares a common ground ("GND") with the input switch signal "Signal". The secondary side is powered by the control power supply "Vcc" and references the control ground "SGND". When the input signal "Signal" is in "ground / on" type and grounded, the anode of the LED on the primary side of optocoupler OP1 is shorted to the input reference ground "GND" through diode D1. The voltage is the diode's voltage drop, approximately 1V, which is less than the LED's on-state voltage threshold (minimum approximately 1.2V). Therefore, the LED is off, and the secondary side output signal "Sig_IN" of optocoupler OP1 is high. When the input signal "Signal" is in "28V / on" type and is 28V, the "Signal" signal voltage is higher than the stable voltage. When diode D2 operates at its threshold voltage, transistor Q1 conducts, and the primary-side LED of optocoupler OP1 is bypassed, with the voltage across it less than 1V, which is below the LED's conduction threshold voltage. The LED is then off, and the secondary-side output signal "Sig_IN" is high. When the input signal "Signal" is "ground / on" or "28V / on" and is in an open-circuit state, the input signal terminal is in a high-impedance state. Both diode D1 and transistor Q1 are off, and the 28V power supply is applied to the primary-side LED of optocoupler OP1 through resistor R2, turning the LED on. The secondary-side output signal "Sig_IN" is low. Thus, the secondary-side output is consistent regardless of whether the input signal is in "ground" or "28V" state, achieving interface compatibility for both "ground / on" and "28V / on" switching signal types.

[0039] When a positive pulse transient voltage surge occurs at the input signal terminal, diode D1, due to its high withstand voltage, is reverse-biased, protecting transistor Q1 and optocoupler OP1 from the high voltage surge. Resistor R3, with its high withstand voltage and large resistance, can limit the surge current to a relatively low value, ensuring that the Zener diode D2 and the base-emitter junction of transistor Q1 are not damaged by the surge current. Resistor R5 is bypassed by the base-emitter junction of transistor Q1 and is not affected by the surge voltage and current. When a negative pulse transient voltage surge occurs at the input signal terminal, diode D3, due to its high withstand voltage, is reverse-biased, protecting all circuits and devices on the primary side of the optocoupler from the high voltage surge.

[0040] Example 2: This embodiment of the invention provides a surge protection method for a surge protection switch signal interface circuit, the method comprising:

[0041] When the input switch signal "Signal" is "ground / on" and grounded, the positive diode 1 conducts, and the primary side of the signal isolation transmission circuit 4 is shorted to the input reference ground through the positive diode 1, resulting in a low-level input signal on the primary side of the signal isolation transmission circuit 4. When the input switch signal "Signal" is "high / on" and is "high," the bypass switch circuit 3 closes, and the primary side of the signal isolation transmission circuit 4 is shorted to the input reference ground through the negative diode 2, resulting in a low-level input signal on the primary side of the signal isolation transmission circuit 4. When the input switch signal "Signal" is "open circuit (high impedance state)," the primary side input signal of the signal isolation transmission circuit 4 is high. In this way, the same circuit achieves compatibility between "ground / on" and "high / on" signal types. Furthermore, when positive or negative pulse surges occur at the positive or negative input signal terminals, they can be blocked by the two diodes, positive diode 1 and negative diode 2. The bypass switch circuit 3 has a larger input impedance and can withstand surges generated at the input terminal.

[0042] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A surge protection switch signal interface circuit, characterized in that, The surge protection switch signal interface circuit is provided with: a positive diode (1), a negative diode (2), a bypass switch circuit (3), and a signal isolation transmission circuit (4); The signal input terminal is connected to the cathode of the positive diode (1) and the control terminal of the bypass switch circuit (3); the bypass switch circuit (3) is connected in parallel with the primary side of the signal isolation transmission circuit (4); the positive terminal of the bypass switch circuit (3) is connected to the anode of the positive diode (1); and the negative terminal of the bypass switch circuit (3) is connected to the anode of the negative diode (2). The cathode of the negative diode (2) is connected to the reference ground of the signal input terminal; The secondary side of the signal isolation transmission circuit (4) is the signal output terminal, which outputs the signal to the control circuit.

2. The surge protection switch signal interface circuit according to claim 1, characterized in that, The signal isolation transmission circuit (4) is equipped with an optocoupler OP1, which is connected to resistors R1, R2 and R4.

3. The surge protection switch signal interface circuit according to claim 2, characterized in that, The primary anode of the optocoupler OP1 in the signal isolation transmission circuit (4) is connected to the 28V power supply through resistor R2, and the secondary collector is connected to the control power supply Vcc through resistor R1. The secondary collector of optocoupler OP1 is the signal output pin.

4. The surge protection switch signal interface circuit according to claim 2, characterized in that, The primary side of the signal isolation transmission circuit (4) shares a common ground with the signal input terminal, and the secondary side references the control ground SGND.

5. The surge protection switch signal interface circuit according to claim 1, characterized in that, The bypass switch circuit (3) is equipped with a transistor Q1, resistors R3 and R5 and a Zener diode D2. The resistor R5 is connected in parallel between the base (B) and emitter (E) of the transistor Q1. The resistor R3 is connected in series with the cathode of the Zener diode D2. The anode of the Zener diode D2 is connected to the base (B) of the transistor Q1. The collector (C) of the transistor Q1 is connected to the anode of the primary-side LED of the optocoupler OP1 in the signal isolation circuit (4). The emitter (E) of the transistor Q1 is connected to the cathode of the primary-side LED of the optocoupler OP1.

6. The surge protection switch signal interface circuit according to claim 5, characterized in that, The other end of the resistor R3 is connected to the cathode of the positive diode (1) and the signal input terminal. The anode of the positive diode (1) is connected to the collector of the transistor Q1 and the anode of the primary-side light-emitting diode of the optocoupler OP1.

7. The surge protection switch signal interface circuit according to claim 5, characterized in that, The emitter of transistor Q1 and the cathode of the primary-side light-emitting diode of optocoupler OP1 are connected to the anode of the negative diode (2), and the cathode of the negative diode (2) is connected to the input signal reference ground.

8. A surge protection method for a surge protection switch signal interface circuit, characterized in that, Applied to the surge protection switch signal interface circuit according to any one of claims 1-7, this method uses a high-voltage diode combined with a bypass switch to perform interface conversion for different types of switch signals, while eliminating the need for low-reliability surge suppression devices, thus achieving interface surge protection; specifically including: When the input switch signal Signal is ground / open and grounded, the positive diode (1) is turned on, and the primary side of the signal isolation transmission circuit (4) is shorted to the input reference ground through the positive diode (1), and the input signal of the primary side of the signal isolation transmission circuit (4) is low. When the input switch signal Signal is high / on and high, the bypass switch circuit (3) is closed, and the primary side of the signal isolation transmission circuit (4) is shorted to the input reference ground through the negative terminal diode (2), and the input signal of the primary side of the signal isolation transmission circuit (4) is low.

9. The surge protection method for the surge protection switch signal interface circuit according to claim 8, characterized in that, The low-reliability surge suppression device is a transient voltage suppressor (TVS) or a varistor.

10. The surge protection method for the surge protection switch signal interface circuit according to claim 8, characterized in that, When the input switch signal Signal is open, the primary input signal of the signal isolation transmission circuit (4) is high level; When a positive pulse surge or a negative pulse surge occurs at the positive or negative terminal of the input signal, the surge voltage can be blocked by the two diodes, the positive terminal diode (1) and the negative terminal diode (2). The surge current value of the bypass switch circuit (3) is limited to a safe level by the resistor R3.

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