Interface circuit with protection function

Abstract

The utility model relates to interface circuit technical field, concretely relates to an interface circuit with protection function, including connector J1, connector J2, thyristor Q2, resistance R2, resistance R4 and stabilivolt diode VT2, the anode of thyristor Q2 is connected with connector J1 and connector J2 respectively, the cathode of thyristor Q2 is grounded, the grid of thyristor Q2 is connected with one end of resistance R2, the other end of resistance R2 is grounded through resistance R4, the other end of resistance R2 is connected with the anode of stabilivolt diode VT2, the cathode of stabilivolt diode VT2 is connected with the anode of thyristor Q2, the utility model discloses that the overvoltage trigger loop that stabilivolt diode VT2 and thyristor Q2 constitute, realize overvoltage threshold accurate control, when overvoltage, thyristor Q2 fast conduction, bypass and form big current loop to load, instantaneous fuse F1, cut off power supply thoroughly, avoid continuous overvoltage damage load.

Description

Technical Field

[0001] This utility model relates to the field of interface circuit technology, and specifically to an interface circuit with protection function. Background Technology

[0002] In the mining environment, electronic products must withstand complex conditions such as high dust, high humidity, electromagnetic interference, and mechanical vibration over long periods. Their operational reliability directly affects mine production safety and operational efficiency, thus imposing stringent requirements on the reliability of circuit design. According to relevant national coal mine safety standards, electronic products used in mines must, while fulfilling basic functions, reserve sufficient electrical safety margins to withstand the impact of extreme environments on the circuits.

[0003] As the connection node between electronic products and external power supply systems, the power input interface is the primary link to ensure the normal startup and stable operation of equipment. Its protection performance directly determines whether the product can pass the initial power supply test and be put into actual use. Therefore, the design of the power protection circuit is regarded as the core link of the overall circuit design of mining electronic products.

[0004] Currently, conventional DC power supply protection circuits generally adopt a protection scheme that combines TVS (Transient Voltage Suppressor) diodes with fuses. The working principle is to use the avalanche breakdown characteristics of TVS diodes to clamp transient overvoltages, while the fuse melts and cuts off the circuit during overcurrent. However, this scheme has significant reliability defects in the application of electronic products in mines and cannot meet the safety requirements of the mine environment.

[0005] The clamping voltage of commonly used TVS diodes is as high as 21.5V, which is much higher than the normal operating voltage of the 12V system commonly used in mining electronic products. When a small overvoltage occurs, the TVS diode cannot activate protection in time, which may damage the downstream circuit. In addition, in the continuous overvoltage scenario that may occur in the mining power supply system, although the TVS diode will break down and conduct, the current in the circuit is still lower than the fusing current of a conventional fuse. The fuse cannot melt and cut off the circuit in time. The continuous overvoltage will directly affect the downstream load chip, eventually causing the chip to burn out, leading to equipment failure or even safety accidents. Utility Model Content

[0006] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing an interface circuit with protective functions.

[0007] The purpose of this utility model is achieved through the following technical solution: an interface circuit with protection function, including connector J1, connector J2, thyristor Q2, resistor R2, resistor R4 and Zener diode VT2;

[0008] The anode of the thyristor Q2 is connected to connector J1 and connector J2 respectively; the cathode of the thyristor Q2 is grounded; the gate of the thyristor Q2 is connected to one end of resistor R2; the other end of resistor R2 is grounded through resistor R4; the other end of resistor R2 is connected to the anode of Zener diode VT2; the cathode of Zener diode VT2 is connected to the anode of thyristor Q2.

[0009] The present invention is further configured such that the interface circuit with protection function also includes a capacitor C5; the capacitor C5 is connected in parallel with the resistor R4.

[0010] The present invention is further configured such that the interface circuit with protection function also includes a unidirectional diode D1; the anode of the unidirectional diode D1 is connected to the connector J1; and the cathode of the unidirectional diode D1 is connected to the anode of the thyristor Q2.

[0011] The present invention is further configured such that the interface circuit with protective function also includes a fuse F1; the fuse F1 is disposed between the anode of the unidirectional diode D1 and the connector J1.

[0012] The present invention is further configured such that the interface circuit with protection function also includes a TVS diode D4; the cathode of the TVS diode D4 is connected to the cathode of the unidirectional diode D1; and the anode of the TVS diode D4 is grounded.

[0013] The present invention is further configured such that the interface circuit with protection function also includes a capacitor C1; one end of the capacitor C1 is connected to the cathode of the unidirectional diode D1; and the other end of the capacitor C1 is grounded.

[0014] The present invention is further configured such that the interface circuit with protection function also includes capacitor C2; capacitor C2 is connected in parallel with capacitor C1.

[0015] The present invention is further configured such that the interface circuit with protection function also includes capacitor C3; capacitor C3 is connected in parallel with capacitor C1.

[0016] The beneficial effects of this utility model are as follows: This utility model achieves precise control of the overvoltage threshold through an overvoltage triggering circuit composed of a Zener diode VT2 and a thyristor Q2; when overvoltage occurs, the thyristor Q2 quickly conducts, bypassing the load and forming a large current circuit, instantly blowing the fuse F1, completely cutting off the power supply, and avoiding continuous overvoltage damage to the load. Attached Figure Description

[0017] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0018] The present invention will be further described in conjunction with the following embodiments.

[0019] Depend on Figure 1 As can be seen, the interface circuit with protection function described in this embodiment includes connector J1, connector J2, silicon controlled rectifier Q2, resistor R2, resistor R4, and Zener diode VT2;

[0020] The anode of the thyristor Q2 is connected to connector J1 and connector J2 respectively; the cathode of the thyristor Q2 is grounded; the gate of the thyristor Q2 is connected to one end of resistor R2; the other end of resistor R2 is grounded through resistor R4; the other end of resistor R2 is connected to the anode of Zener diode VT2; the cathode of Zener diode VT2 is connected to the anode of thyristor Q2.

[0021] Specifically, in the interface circuit with protection function described in this embodiment, the anode of the thyristor Q2 serves as the core node, simultaneously receiving the input of connector J1 and the output of connector J2. The gate of the thyristor Q2 forms a voltage divider circuit through resistors R2 and R4, and resistor R2 is connected to the anode of the Zener diode VT2. The cathode of the Zener diode VT2 is connected back to the anode of the thyristor Q2, thus forming an overvoltage detection and triggering closed loop.

[0022] When the input voltage of connector J1 is normal, the voltage across Zener diode VT2 does not reach its reverse breakdown threshold (12.4V-14.1V), causing Zener diode VT2 to be cut off. The gate of thyristor Q2 has no trigger voltage, and thyristor Q2 remains in the off state. At this time, the current flows normally to the load through the anode of thyristor Q2 and connector J2. When the input voltage is overvoltage (e.g., ≥12.4V), Zener diode VT2 breaks down in reverse and clamps the voltage. The current flows to ground through Zener diode VT2 and resistor R4. After the voltage is divided by resistors R2 and R4, the gate of thyristor Q2 receives a voltage greater than the trigger voltage, causing thyristor Q2 to conduct, bypassing the load and forming a large current loop.

[0023] This embodiment relies on the voltage regulation characteristics of the Zener diode VT2 to achieve controllable overvoltage threshold (maximum 15.1V, minimum >12.4V), avoiding false triggering due to voltage fluctuations and activating protection only for actual overvoltage scenarios. Furthermore, the thyristor Q2 has extremely low internal resistance (milliohms) after conduction, which can instantly generate a large current exceeding the rated current of fuse F1 (e.g., 1.5A). This provides crucial conditions for subsequently blowing fuse F1 and completely cutting off the power supply circuit, fundamentally preventing continuous damage to the load from overvoltage.

[0024] This embodiment describes an interface circuit with a protective function, which further includes a capacitor C5; the capacitor C5 is connected in parallel with the resistor R4. Specifically, the parallel connection of capacitor C5 and resistor R4 utilizes the characteristic of capacitor C5 to pass high frequencies and block low frequencies, absorbing high-frequency interference signals coupled in the power supply line (such as instantaneous high-frequency voltage generated by electromagnetic radiation); under normal overvoltage scenarios, the capacitance value of capacitor C5 (10N) is moderate and will not affect the voltage divider logic of resistor R4 or the triggering speed of the thyristor Q2, only filtering high-frequency interference.

[0025] Capacitor C5 can effectively suppress the false breakdown of Zener diode VT2 and the false triggering of SCR Q2 caused by high-frequency interference, avoid protection actions in non-overvoltage scenarios (such as the false blowing of fuse F1), and ensure the stability of normal operation of the equipment; in addition, it can ensure that SCR Q2 is triggered only in the event of actual overvoltage, eliminate the false influence of interference signals on the protection circuit, and improve the applicability of the circuit in complex electromagnetic environments (such as mines).

[0026] This embodiment describes an interface circuit with a protective function, which further includes a unidirectional diode D1. The anode of the unidirectional diode D1 is connected to connector J1, and the cathode of the unidirectional diode D1 is connected to the anode of the silicon controlled rectifier (SCR) Q2. Specifically, the unidirectional diode D1 has the characteristic of forward conduction and reverse cutoff, allowing current to flow unidirectionally only from connector J1, diode D1 anode, diode D1 cathode, SCR Q2 anode, and connector J2. If the positive and negative terminals of the input power supply to connector J1 are reversed, the current path can be blocked, preventing reverse power supply from causing reverse breakdown damage to the downstream load chip.

[0027] This embodiment describes an interface circuit with a protective function, which further includes a fuse F1. The fuse F1 is located between the anode of the unidirectional diode D1 and the connector J1. The fuse F1 is a one-time overcurrent protection device, with a rated current (e.g., 1.5A) matching the upper limit of the normal operating current of the load. When the load is short-circuited or the thyristor Q2 is turned on (overvoltage scenario), causing the loop current to be greater than 1.5A, the fuse F1 melts rapidly due to Joule heating, cutting off the power input path from the connector J1 to the subsequent circuit.

[0028] This embodiment describes an interface circuit with a protective function, which further includes a TVS diode D4. The cathode of the TVS diode D4 is connected to the cathode of the unidirectional diode D1, and the anode of the TVS diode D4 is grounded. Specifically, the TVS diode D4 has avalanche breakdown characteristics. When transient static electricity (e.g., thousands of volts) is coupled to the circuit through connector J1 or the line, the voltage across the TVS diode D4 rises sharply. When the voltage reaches the TVS diode avalanche breakdown threshold (14.4V-15.9V), the TVS diode D4 conducts instantaneously, rapidly discharging the static current to ground and clamping the voltage to the transient maximum value (e.g., 21.5V) to prevent static voltage from impacting the load. To address electrostatic interference that is prone to occur in dry environments such as mines, a millisecond-level response discharge channel is provided to prevent electrostatic discharge from damaging the precision pins of load chips (such as the signal pins of image sensors). In addition, under normal voltage and overvoltage scenarios, the voltage across the TVS diode D4 does not reach the breakdown threshold and remains in the cutoff state, without affecting the normal operation logic of devices such as unidirectional diode D1, thyristor Q2, and fuse F1.

[0029] This embodiment describes an interface circuit with a protective function, which further includes a capacitor C1. One end of the capacitor C1 is connected to the cathode of a unidirectional diode D1, and the other end of the capacitor C1 is grounded. By connecting the capacitor C1 in parallel between the cathode of the unidirectional diode D1 and ground, the energy storage characteristics of the capacitor C1 are used to filter the power supply rectified by the unidirectional diode D1.

[0030] This embodiment describes an interface circuit with a protective function, which further includes a capacitor C2; the capacitor C2 is connected in parallel with the capacitor C1. By connecting the capacitor C2 in parallel between the cathode of the unidirectional diode D1 and ground, the energy storage characteristics of the capacitor C2 are utilized to further filter the power supply rectified by the unidirectional diode D1.

[0031] This embodiment describes an interface circuit with a protective function, which further includes a capacitor C3; the capacitor C3 is connected in parallel with the capacitor C1. By connecting the capacitor C3 in parallel between the cathode of the unidirectional diode D1 and ground, the energy storage characteristics of the capacitor C3 are utilized to further filter the power supply rectified by the unidirectional diode D1.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. An interface circuit with protective function, characterized in that: This includes connector J1, connector J2, silicon controlled rectifier Q2, resistor R2, resistor R4, and Zener diode VT2; The anode of the thyristor Q2 is connected to connector J1 and connector J2 respectively; the cathode of the thyristor Q2 is grounded; the gate of the thyristor Q2 is connected to one end of resistor R2; the other end of resistor R2 is grounded through resistor R4; the other end of resistor R2 is connected to the anode of Zener diode VT2; the cathode of Zener diode VT2 is connected to the anode of thyristor Q2.

2. The interface circuit with protection function according to claim 1, characterized in that: The interface circuit with protection function also includes capacitor C5; capacitor C5 is connected in parallel with resistor R4.

3. The interface circuit with protection function according to claim 1, characterized in that: The interface circuit with protection function also includes a unidirectional diode D1; the anode of the unidirectional diode D1 is connected to the connector J1; the cathode of the unidirectional diode D1 is connected to the anode of the thyristor Q2.

4. The interface circuit with protection function according to claim 3, characterized in that: The interface circuit with protective function also includes a fuse F1; the fuse F1 is located between the anode of the unidirectional diode D1 and the connector J1.

5. The interface circuit with protection function according to claim 3, characterized in that: The interface circuit with protection function also includes a TVS diode D4; the cathode of the TVS diode D4 is connected to the cathode of the unidirectional diode D1; the anode of the TVS diode D4 is grounded.

6. The interface circuit with protection function according to claim 3, characterized in that: The interface circuit with protection function also includes a capacitor C1; one end of the capacitor C1 is connected to the cathode of the unidirectional diode D1; the other end of the capacitor C1 is grounded.

7. An interface circuit with protection function according to claim 6, characterized in that: The interface circuit with protection function also includes capacitor C2; capacitor C2 is connected in parallel with capacitor C1.

8. An interface circuit with protection function according to claim 7, characterized in that: The interface circuit with protection function also includes capacitor C3; capacitor C3 is connected in parallel with capacitor C1.

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