Vehicle-mounted 28V surge suppression circuit

Abstract

The invention belongs to the technical field of surge suppression, and particularly discloses a vehicle-mounted 28V surge suppression circuit which mainly comprises a high-voltage surge suppression chip U1, MOS transistors VQ4 and VQ5, resistors R7, R8, R9 and R10 and a voltage stabilizing diode D7. Through the design of the whole circuit, input reverse connection protection, input under-voltage protection and input over-voltage protection can be realized on the basis of realizing input surge voltage clamping. The suppression of the input surge voltage can ensure that the vehicle-mounted equipment can bear up to 100V instantaneous voltage in GJB 298-87 Vehicle 28V DC electrical system characteristics, and the damage of an internal power supply and a rear-end load of the equipment due to overhigh input voltage is avoided. Meanwhile, compared with the mode of adopting a Schottky diode in the traditional application, the input reverse connection protection function realized by the circuit can effectively reduce the loss of the device and improve the efficiency of the power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of surge suppression, and in particular to a vehicle-mounted 28V surge suppression circuit. Background Art

[0002] Surge, also known as transient surge, is a sudden change in high voltage in the circuit. This change usually lasts for a very short time, but it may cause serious damage to electronic equipment and circuits. For the protection of surge circuits, it is necessary to design a built-in surge protection circuit. In previous designs, they were all designed based on an ideal state. The most common method is to use anti-reverse diodes, transient suppression diodes (TVS) or varistors. Summary of the invention

[0003] The purpose of the present invention is to solve the technical problems existing in the background technology. To this end, a vehicle-mounted 28V surge suppression circuit is provided.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A vehicle-mounted 28V surge suppression circuit, comprising a high-voltage surge suppression chip U1, MOS tubes VQ4 and VQ5, resistors R7, R8, R9 and R10, and a voltage stabilizing diode D7;

[0006] The drains of the MOS tube VQ4 and the MOS tube VQ5 are connected and electrically connected to the output end of the input reverse connection protection circuit;

[0007] The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of the MOS tube VQ4 through the resistor R7, and the GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of the MOS tube VQ5 through the resistor R8;

[0008] The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the cathode of the voltage stabilizing diode D7, and the anode of the voltage stabilizing diode D7 is electrically connected to the source of the MOS tube VQ4 and the source of the MOS tube VQ5 respectively;

[0009] The OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the source of the MOS tube VQ4 and the source of the MOS tube VQ5, and the OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the input end of the DC-DC conversion circuit;

[0010] The FB pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R9 and one end of the resistor R10 respectively, the other end of the resistor R9 is electrically connected to the OUT pin of the high-voltage surge suppression chip U1, and the other end of the resistor R10 is grounded.

[0011] The following is a technical solution further defined in the present invention: the TMR pin of the high-voltage surge suppression chip U1 is grounded through a capacitor C2, and the GND pin of the high-voltage surge suppression chip U1 is grounded.

[0012] The following is a technical solution further defined in the present invention: the OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the positive electrode of the electrolytic capacitor C3, and the negative electrode of the electrolytic capacitor C3 is grounded.

[0013] The following is a technical solution further defined in the present invention: the GATE pin of the high-voltage surge suppression chip U1 is grounded through a capacitor C1.

[0014] The following is a technical solution further defined in the present invention, wherein the input reverse connection protection circuit includes MOS tubes VQ2 and VQ3, resistors R1, R2, R3, R4 and R6, diodes D2 and D6, and a transistor VQ1;

[0015] The sources of the MOS tube VQ2 and the MOS tube VQ3 are connected and connected to the positive electrode of the 28V power supply voltage;

[0016] The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the positive electrode of the diode D6, the negative electrode of the diode D6 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R3 and one end of the resistor R4 respectively;

[0017] The other end of the resistor R3 is electrically connected to the gate of the MOS transistor VQ2, and the other end of the resistor R4 is electrically connected to the gate of the MOS transistor VQ3;

[0018] The drains of the MOS tube VQ2, the MOS tube VQ3, the MOS tube VQ4 and the MOS tube VQ5 are connected;

[0019] A resistor R1 is electrically connected between the positive and negative electrodes of the supply voltage, the negative electrode of the supply voltage is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is electrically connected to the base of the transistor VQ1, the collector of the transistor VQ1 is electrically connected to the line between the resistor R6 and the resistor R4, and the emitter of the transistor VQ1 is electrically connected to the positive electrode of the supply voltage.

[0020] The following is a technical solution further defined by the present invention, a diode D3 is electrically connected between the base and emitter of the transistor VQ1, wherein the emitter of the transistor VQ1 is electrically connected to the anode of the diode D3, and the base of the transistor VQ1 is electrically connected to the cathode of the diode D3.

[0021] The following is a technical solution further defined by the present invention, wherein a Zener diode D4 is electrically connected between the emitter and collector of the transistor VQ1, wherein the anode of the Zener diode D4 is electrically connected to the emitter of the transistor VQ1, and the cathode of the Zener diode D4 is electrically connected to the collector of the transistor VQ1.

[0022] The following is a technical solution further defined by the present invention, in which a bidirectional transient suppression diode D1 is electrically connected between the positive and negative electrodes of the power supply voltage, the VCC pin of the high-voltage surge suppression chip U1 is electrically connected to the drain of the MOS tube VQ2 through a resistor R5, and the VCC pin of the high-voltage surge suppression chip U1 is grounded through a parallel-connected voltage regulator diode D8 and a capacitor C4.

[0023] The following is a technical solution further defined in the present invention, further comprising an input undervoltage protection circuit, wherein the input undervoltage protection circuit comprises a resistor R11 and a resistor R13;

[0024] The UV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R11 and one end of the resistor R13 respectively, the other end of the resistor R13 is grounded, and the other end of the resistor R11 is electrically connected to the drain of the MOS tube VQ2.

[0025] The following is a technical solution further defined by the present invention, further comprising an input overvoltage protection circuit, wherein the input overvoltage protection circuit comprises a resistor R12 and a resistor R14;

[0026] The OV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R12 and one end of the resistor R14, the other end of the resistor R14 is grounded, and the other end of the resistor R12 is electrically connected to the drain of the MOS tube VQ2.

[0027] Compared with the prior art, the present invention has the following technical effects:

[0028] The present invention can realize input reverse connection protection, input undervoltage protection and input overvoltage protection at the same time on the basis of realizing input surge voltage clamping through the design of the overall circuit. The suppression of input surge voltage can ensure that the vehicle-mounted equipment can withstand the instantaneous voltage of up to 100V in GJB 298-87 "Characteristics of 28V DC Electrical System of Vehicles", and avoid damage to the internal power supply of the equipment and the rear-end load due to excessive input voltage. At the same time, the input reverse connection protection function realized by the circuit can effectively reduce the loss of the device and improve the efficiency of the power supply compared with the method of using Schottky diodes in traditional applications.

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a circuit connection principle diagram of the present invention. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0033] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a direct electrical connection or an indirect electrical connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0034] The on-board 28V DC power-consuming equipment is mainly composed of power boards and functional boards. The power boards usually convert the DC 28V voltage into the commonly used 12V, 5V, and 3.3V low-voltage outputs through isolated DC / DC conversion for use by subsequent functional boards.

[0035] like Figure 1 As shown, this embodiment proposes a vehicle-mounted 28V surge suppression circuit (also known as a vehicle-mounted 28V DC power supply surge suppression circuit), which can ensure that the equipment meets the surge voltage requirements in GJB 298-87 "Characteristics of 28V DC Electrical System of Vehicles". The circuit adopts a domestic surge suppression chip U1 (U1 model is SM4363MP), and uses the linear working area of ​​the MOS tube to control the conduction degree of the MOS tube, thereby limiting the output voltage. At the same time, the circuit can also realize input undervoltage, input overvoltage, and input reverse connection protection. Compared with the traditional processing method, this circuit design can not only realize input surge protection, but also realize input undervoltage, input overvoltage, input reverse connection protection, etc., and occupies a small volume, does not require complicated shunt circuits (TVS tubes, varistors, capacitors and inductors, etc.), and is more convenient to implement.

[0036] The circuit principle of this embodiment is to add a surge suppression chip, MOS tube, resistor and capacitor and other devices to the input end of the power board in the electrical equipment. This circuit can achieve: meet the 100V surge voltage requirement in GJB 298-87 "Characteristics of 28V DC Electrical System in Vehicles", avoid serious damage to electronic equipment and circuits, and ensure the normal operation of the functional board in the electrical equipment. Figure 1 The figure shows the principle of DC 28V surge suppression circuit.

[0037] A vehicle-mounted 28V surge suppression circuit is mainly composed of a high-voltage surge suppression chip U1 (U1 model is SM4363MP), a transistor VQ1, NMOS tubes VQ2, VQ3, VQ4, VQ5 (MOS tube: metal oxide semiconductor field effect transistor), resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, a bidirectional transient suppression diode D1, diodes D2, D3, D6, voltage regulator diodes D4, D7, D8, capacitors C1, C2, C4, an electrolytic capacitor C3, and the like.

[0038] The drains of MOS tubes VQ2, VQ3, VQ4 and VQ5 are connected. The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of MOS tube VQ4 through resistor R7, and the GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of MOS tube VQ5 through resistor R8.

[0039] The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the negative electrode of the voltage-stabilizing diode D7, and the positive electrode of the voltage-stabilizing diode D7 is electrically connected to the source electrode of the MOS tube VQ4 and the source electrode of the MOS tube VQ5. The OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the source electrode of the MOS tube VQ4 and the source electrode of the MOS tube VQ5, and the OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the input end of the DC-DC conversion circuit (DC-DC: DC input to DC output). The FB pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R9 and one end of the resistor R10, respectively, and the other end of the resistor R9 is electrically connected to the OUT pin of the high-voltage surge suppression chip U1, and the other end of the resistor R10 is grounded. The TMR pin of the high-voltage surge suppression chip U1 is grounded through the capacitor C2, and the GND pin of the high-voltage surge suppression chip U1 is grounded. The OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the positive electrode of the electrolytic capacitor C3, and the negative electrode of the electrolytic capacitor C3 is grounded. The GATE pin of the high-voltage surge suppression chip U1 is grounded through a capacitor C1.

[0040] Figure 1In the figure, 28VIN is the 28V power supply voltage, D1 is a bidirectional transient suppression diode, which is used to absorb the peak voltage with a pulse width of μs at the input end, VQ2 and VQ3 and their peripheral control circuits realize the input reverse connection protection function, and VQ4 and VQ5 and their peripheral control circuits realize input surge voltage suppression.

[0041] When the input is positive, Figure 1 The medium and high voltage surge suppression chip U1 works, the GATE pin outputs the MOS tube drive voltage, and the NMOS tubes VQ2~VQ5 are fully turned on to supply power to the rear-end load. According to the requirements of GJB 298-87 "Characteristics of 28V DC Electrical System of Vehicles", when a 100V surge voltage appears at the 28VIN terminal, Figure 1 The FB pin of the U1 chip detects that the pin voltage is higher than the reference voltage VREF1 inside the chip through the resistor R9 and R10 voltage divider, thereby quickly reducing the driving voltage of the GATE pin. The MOS tubes VQ4 and VQ5 are now working in the linear working area. Through the closed-loop adjustment inside the chip, the output end 28V+ voltage is finally clamped at VREF1*(R9+R10) / R10. The clamping time of the overvoltage surge can be set through the TMR pin of the U1 chip and the capacitor C2. When the input is positively connected, due to Figure 1 With the addition of diode D3, the voltage VBE between the base and emitter of transistor VQ1 is clamped at about -0.3V to -0.7V, which is lower than the conduction threshold voltage of VBE. Transistor VQ1 is not turned on and will not affect the driving voltage of VQ2 and VQ3.

[0042] The input reverse connection protection circuit is specifically as follows: the source electrodes of the MOS tube VQ2 and the MOS tube VQ3 are connected and connected to the positive electrode of the power supply voltage. The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the positive electrode of the diode D6, the negative electrode of the diode D6 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R3 and one end of the resistor R4. The other end of the resistor R3 is electrically connected to the gate of the MOS tube VQ2, and the other end of the resistor R4 is electrically connected to the gate of the MOS tube VQ3. A resistor R1 is electrically connected between the positive and negative electrodes of the power supply voltage, the negative electrode of the power supply voltage is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is electrically connected to the base of the transistor VQ1, the collector of the transistor VQ1 is electrically connected to the line between the resistor R6 and the resistor R4, and the emitter of the transistor VQ1 is electrically connected to the positive electrode of the power supply voltage.

[0043] A diode D3 is electrically connected between the base and emitter of the transistor VQ1, wherein the emitter of the transistor VQ1 is electrically connected to the positive electrode of the diode D3, and the base of the transistor VQ1 is electrically connected to the negative electrode of the diode D3. A voltage regulator diode D4 is electrically connected between the emitter and collector of the transistor VQ1, wherein the positive electrode of the voltage regulator diode D4 is electrically connected to the emitter of the transistor VQ1, and the negative electrode of the voltage regulator diode D4 is electrically connected to the collector of the transistor VQ1. A bidirectional transient suppression diode D1 is electrically connected between the positive and negative electrodes of the power supply voltage, and the VCC pin of the high-voltage surge suppression chip U1 is electrically connected to the drain of the MOS tube VQ2 through the resistor R5, and the VCC pin of the high-voltage surge suppression chip U1 is grounded through the parallel voltage regulator diode D8 and the capacitor C4.

[0044] When the input is reversed, the reverse voltage passes through Figure 1 The middle resistor R2 and the diode D2 are input to the base of the transistor VQ1, the transistor VQ1 is turned on, and the GATE pin voltage of the high-voltage surge suppression chip U1 is continuously pulled down through the resistor R6 and the diode D6. The MOS tubes VQ2~VQ5 have no driving voltage and are not turned on, thereby realizing the input reverse connection protection function.

[0045] This circuit can realize input undervoltage and overvoltage protection functions, specifically:

[0046] The input undervoltage protection circuit is specifically as follows: the UV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R11 and one end of the resistor R13, the other end of the resistor R13 is grounded, and the other end of the resistor R11 is electrically connected to the drain of the MOS tube VQ2.

[0047] Therefore, the input undervoltage protection circuit is realized through the UV pin of the high-voltage surge suppression chip U1 and the voltage division of resistors R11 and R13. The overvoltage comparison reference value inside the chip is VREF2. When the input voltage is higher than VREF2*(R11+R13) / R13, the GATE pin of U1 is pulled low, and the MOS tubes VQ2~VQ5 have no driving voltage and are not turned on, thereby realizing the input undervoltage protection function.

[0048] The input overvoltage protection circuit is specifically as follows: the OV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R12 and one end of the resistor R14, the other end of the resistor R14 is grounded, and the other end of the resistor R12 is electrically connected to the drain of the MOS tube VQ2.

[0049] Therefore, the input overvoltage protection circuit is realized through the OV pin of the high-voltage surge suppression chip U1 and the voltage division of resistors R12 and R14. The overvoltage comparison reference value inside the chip is VREF3. When the input voltage is higher than VREF3*(R12+R14) / R14, Figure 1When the circuit in the middle works in the input surge suppression state, the GATE pin of U1 is pulled low, and the MOS tubes VQ2~VQ5 have no driving voltage and are not turned on, thereby realizing the input overvoltage protection function.

[0050] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention without departing from the content of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A vehicle-mounted 28V surge suppression circuit, characterized in that: Including high-voltage surge suppression chip U1, MOS tubes VQ4, VQ5, resistors R7, R8, R9, R10, and voltage regulator diode D7; The drains of the MOS tube VQ4 and the MOS tube VQ5 are connected and electrically connected to the output end of the input reverse connection protection circuit; The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of the MOS tube VQ4 through the resistor R7, and the GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the gate of the MOS tube VQ5 through the resistor R8; The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the source of the MOS tube VQ4 and the source of the MOS tube VQ5 through the voltage stabilizing diode D7; The OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the source of the MOS tube VQ4 and the source of the MOS tube VQ5, and the OUT pin of the high-voltage surge suppression chip U1 is electrically connected to the input end of the DC-DC conversion circuit; The FB pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R9 and one end of the resistor R10 respectively, the other end of the resistor R9 is electrically connected to the OUT pin of the high-voltage surge suppression chip U1, and the other end of the resistor R10 is grounded.

2. A vehicle-mounted 28V surge suppression circuit as claimed in claim 1, characterized in that: The TMR pin of the high-voltage surge suppression chip U1 is grounded through the capacitor C2, and the GND pin of the high-voltage surge suppression chip U1 is grounded.

3. The vehicle-mounted 28V surge suppression circuit according to claim 1, characterized in that: The OUT pin of the high-voltage surge suppression chip U1 is grounded via an electrolytic capacitor C3.

4. The vehicle-mounted 28V surge suppression circuit according to claim 1, characterized in that: The GATE pin of the high-voltage surge suppression chip U1 is grounded through a capacitor C1.

5. The vehicle-mounted 28V surge suppression circuit according to claim 1, characterized in that: The input reverse connection protection circuit includes MOS tubes VQ2 and VQ3, resistors R1, R2, R3, R4 and R6, diodes D2 and D6, and transistor VQ1; The sources of the MOS tube VQ2 and the MOS tube VQ3 are connected and connected to the positive electrode of the power supply voltage; The GATE pin of the high-voltage surge suppression chip U1 is electrically connected to the positive electrode of the diode D6, the negative electrode of the diode D6 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to one end of the resistor R3 and one end of the resistor R4 respectively; The other end of the resistor R3 is electrically connected to the gate of the MOS transistor VQ2, and the other end of the resistor R4 is electrically connected to the gate of the MOS transistor VQ3; The drains of the MOS tube VQ2, the MOS tube VQ3, the MOS tube VQ4 and the MOS tube VQ5 are connected; A resistor R1 is electrically connected between the positive and negative electrodes of the supply voltage, the negative electrode of the supply voltage is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is electrically connected to the base of the transistor VQ1, the collector of the transistor VQ1 is electrically connected to the line between the resistor R6 and the resistor R4, and the emitter of the transistor VQ1 is electrically connected to the positive electrode of the supply voltage.

6. A vehicle-mounted 28V surge suppression circuit as claimed in claim 5, characterized in that: A diode D3 is electrically connected between the base and the emitter of the transistor VQ1 .

7. A vehicle-mounted 28V surge suppression circuit as claimed in claim 5, characterized in that: A voltage stabilizing diode D4 is electrically connected between the emitter and the collector of the transistor VQ1 .

8. The vehicle-mounted 28V surge suppression circuit as claimed in claim 5, characterized in that: A bidirectional transient suppression diode D1 is electrically connected between the positive and negative poles of the supply voltage, and the VCC pin of the high-voltage surge suppression chip U1 is electrically connected to the drain of the MOS tube VQ2 through a resistor R5. The VCC pin of the high-voltage surge suppression chip U1 is grounded through a parallel-connected zener diode D8 and a capacitor C4.

9. The vehicle-mounted 28V surge suppression circuit according to claim 1, characterized in that: It also includes an input undervoltage protection circuit, which includes a resistor R11 and a resistor R13; The UV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R11 and one end of the resistor R13 respectively, the other end of the resistor R13 is grounded, and the other end of the resistor R11 is electrically connected to the output end of the input reverse connection protection circuit.

10. The vehicle-mounted 28V surge suppression circuit according to claim 1, characterized in that: Also included is an input overvoltage protection circuit, the input overvoltage protection circuit includes a resistor R12 and a resistor R14; The OV pin of the high-voltage surge suppression chip U1 is electrically connected to one end of the resistor R12 and one end of the resistor R14, the other end of the resistor R14 is grounded, and the other end of the resistor R12 is electrically connected to the output end of the input reverse connection protection circuit.

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