Protection circuit and vehicle power utilization system

Abstract

The utility model provides a protection circuit and a vehicle power utilization system, and relates to the technical field of electronic circuits. The protection circuit comprises a voltage clamping unit, a voltage comparison unit and a first switch unit, wherein one end of the voltage clamping unit is connected with a power supply input end, the other end of the voltage clamping unit is connected with a first input end of the voltage comparison unit, and the voltage clamping unit is used for clamping the voltage of the power supply input end to a first voltage and outputting the first voltage to the voltage comparison unit; the second input end of the voltage comparison unit is connected with a preset voltage reference point, the output end of the voltage comparison unit is connected with the control end of the first switch unit, and the voltage comparison unit is used for turning off the first switch unit when the first voltage is larger than the voltage input by the preset voltage reference point; the first end of the first switch unit is connected with the power input end, and the second end of the first switch unit is connected with the voltage output end. Therefore, when a load throwing event occurs, high voltage is clamped, overvoltage protection is realized, and damage to electric equipment is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, and in particular to a protection circuit and a vehicle power system. Background Art

[0002] With the development of the automobile industry, there are more and more electrical devices in cars, and the internal structure is complex.

[0003] When debugging and using a car, the power supply system will generate a large-amplitude pulse (up to 200V) when the car engine is stopped, the windows are raised or lowered, the wipers are started, etc., and the instantaneous voltage can easily damage the electrical equipment at the back end.

[0004] Therefore, a protection circuit for an automobile is urgently needed. Utility Model Content

[0005] The purpose of the present invention is to address the deficiencies in the above-mentioned prior art and to provide a protection circuit and a vehicle power system to solve the problems in the prior art such as the damage to electrical equipment caused by instantaneous high voltage.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] In a first aspect, an embodiment of the present application provides a protection circuit, the protection circuit comprising: a voltage clamping unit, a voltage comparison unit, and a first switching unit;

[0008] Wherein, one end of the voltage clamping unit is connected to the power input end, and the other end of the voltage clamping unit is connected to the first input end of the voltage comparison unit, and the voltage clamping unit is used to clamp the voltage of the power input end to a first voltage and output it to the voltage comparison unit;

[0009] The second input terminal of the voltage comparison unit is connected to a preset voltage reference point, the output terminal of the voltage comparison unit is connected to the control terminal of the first switch unit, and the voltage comparison unit is used to turn off the first switch unit when the first voltage is greater than the voltage inputted at the preset voltage reference point;

[0010] A first end of the first switch unit is connected to the power input end, and a second end of the first switch unit is connected to the voltage output end.

[0011] Optionally, the voltage clamping unit is a transient voltage suppression device.

[0012] Optionally, the voltage comparison unit includes: an operational amplifier, a first voltage divider circuit, and a voltage stabilizing circuit;

[0013] One end of the first voltage divider circuit is the first input end of the voltage comparison unit, connected to the other end of the voltage clamping unit, the other end of the first voltage divider circuit is grounded, and the voltage dividing point of the first voltage divider circuit is connected to the non-inverting input end of the operational amplifier;

[0014] The input end of the voltage stabilizing circuit is connected to the first end of the first switch unit, and the first output end of the voltage stabilizing circuit is connected to the positive power supply end of the operational amplifier;

[0015] The negative power supply terminal of the operational amplifier is grounded, the inverting input terminal of the operational amplifier is the second input terminal of the voltage comparison unit, and is used to connect the second output terminal of the voltage stabilizing circuit, and the output terminal of the operational amplifier is the output terminal of the voltage comparison unit.

[0016] Optionally, the voltage stabilizing circuit includes: a current limiting resistor, a voltage stabilizing diode, and a second voltage divider circuit, the first end of the first switch unit is connected to the anode of the voltage stabilizing diode through the current limiting resistor, the cathode of the voltage stabilizing diode is grounded, and the anode of the voltage stabilizing diode is the first output end of the voltage stabilizing circuit;

[0017] The anode of the voltage stabilizing diode is also grounded through the second voltage dividing circuit, and the voltage dividing point of the second voltage dividing circuit is the second output end of the voltage stabilizing circuit.

[0018] Optionally, the protection circuit also includes: a switching circuit, the control end of the switching circuit is connected to the output end of the voltage comparison unit, the first end of the switching circuit is connected to the first end of the first switching unit, the second end of the switching circuit is grounded, and the third end of the switching circuit is connected to the control end of the first switching unit.

[0019] Optionally, the switch circuit includes: a third voltage divider circuit, a fourth voltage divider circuit, a first switch tube and a second switch tube;

[0020] One end of the third voltage divider circuit is the control end of the switch circuit, the other end of the third voltage divider circuit is grounded, and the voltage dividing point of the third voltage divider circuit is connected to the control end of the first switch tube;

[0021] The first end of the first switch unit is also grounded through the fourth voltage-dividing circuit, the voltage-dividing point of the fourth voltage-dividing circuit is respectively connected to the first end of the first switch tube and the control end of the second switch tube, the second end of the first switch tube and the second end of the second switch tube are both grounded, and the first end of the second switch tube is the third end of the switch circuit.

[0022] Optionally, the first switch tube and the second switch tube are both NPN transistors, the first end of the first switch tube and the second switch tube is the collector of the NPN transistor, the second end of the first switch tube and the second switch tube is the emitter of the NPN transistor, and the third end of the first switch tube and the second switch tube is the base of the NPN transistor.

[0023] Optionally, the protection circuit further includes: a second switch unit;

[0024] A first end of the second switch unit is connected to the power input end, a second end of the second switch unit is connected to the first end of the first switch unit, and a control end of the second switch unit is grounded.

[0025] Optionally, the first switch unit is a first PMOS switch unit, and the second switch unit is a second PMOS switch unit;

[0026] The first end of the first switch unit is the source of the first PMOS switch unit, the second end of the first switch unit is the drain of the first PMOS switch unit, and the control end of the first switch unit is the gate of the first PMOS switch unit;

[0027] The first end of the second switch unit is the drain of the second PMOS switch unit, the second end of the second switch unit is the source of the second PMOS switch unit, and the control end of the second switch unit is the gate of the second PMOS switch unit.

[0028] In a second aspect, an embodiment of the present application provides a vehicle power system, comprising: a vehicle power supply device, a vehicle power device, and a protection circuit as described in any one of the first aspects above; the vehicle power supply device is connected to the vehicle power device via the protection circuit.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] The present application provides a protection circuit and a vehicle power system, the protection circuit comprising: a voltage clamping unit, a voltage comparison unit, and a first switch unit; wherein one end of the voltage clamping unit is connected to a power input terminal, and the other end of the voltage clamping unit is connected to a first input terminal of the voltage comparison unit. The voltage clamping unit is configured to clamp the voltage at the power input terminal to a first voltage and output it to the voltage comparison unit; the second input terminal of the voltage comparison unit is connected to a preset voltage reference point, and the output terminal of the voltage comparison unit is connected to a control terminal of a first switch unit. The voltage comparison unit is configured to turn off the first switch unit when the first voltage is greater than the voltage input at the preset voltage reference point; the first end of the first switch unit is connected to the power input terminal, and the second end of the first switch unit is connected to the voltage output terminal. Thus, by providing the voltage clamping unit, the high voltage is clamped when a load dump event occurs, and overvoltage protection is implemented through the voltage comparison unit and the first switch unit, thereby preventing damage to electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A schematic diagram of the structure of a protection circuit provided in an embodiment of the present application;

[0033] Figure 2 A schematic structural diagram of another protection circuit provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the structure of another protection circuit provided in an embodiment of the present application;

[0035] Figure 4 A structural diagram of another protection circuit provided in an embodiment of the present application.

[0036] Icons: 1-voltage clamping unit, 2-voltage comparison unit, 3-first switch unit, D1-TVS device, U1-operational amplifier, 22-voltage regulator circuit, R1-first resistor, R2-second resistor, R3-current limiting resistor, D2-voltage regulator diode, R4-fourth resistor, R5-fifth resistor, 4-switch circuit, Q1-first switch tube, Q2-second switch tube, R6-sixth resistor, R7-seventh resistor, R8-eighth resistor, R9-ninth resistor, 5-second switch unit, R10-tenth resistor, R11-eleventh resistor, R12-twelfth resistor, C1-first capacitor, C2-second capacitor. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0040] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0041] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention can be combined with each other.

[0042] A protection circuit provided in this application is explained below through a specific example.

[0043] Figure 1 This is a schematic diagram of the structure of a protection circuit provided in an embodiment of the present application. Figure 1 As shown, the protection circuit includes: a voltage clamping unit 1 , a voltage comparing unit 2 and a first switching unit 3 .

[0044] Among them, one end of the voltage clamping unit 1 is connected to the power input terminal (VCC IN), and the other end of the voltage clamping unit 1 is grounded and connected to the first input terminal of the voltage comparison unit 2. The voltage clamping unit 1 is used to clamp the voltage of the power input terminal to a first voltage and output it to the voltage comparison unit 2.

[0045] The second input end of the voltage comparison unit 2 is connected to a preset voltage reference point, the output end of the voltage comparison unit 2 is connected to the control end of the first switch unit 3, and the voltage comparison unit 2 is used to turn off the first switch unit 3 when the first voltage is greater than the voltage input at the preset voltage reference point.

[0046] A first end of the first switch unit 3 is connected to the power input end, and a second end of the first switch unit 3 is connected to the voltage output end (VCC OUT).

[0047] For example, a ground terminal of the voltage comparison unit 2 is connected to the other terminal of the voltage clamping unit 1 and is grounded.

[0048] The main current of the protection circuit flows to: the power input terminal, the first switch unit 3, and the voltage output terminal.

[0049] When a load dump event occurs in a vehicle, a power pulse up to 200V first passes through voltage clamping unit 1, which clamps the voltage to a preset clamping voltage (the preset clamping voltage is determined by the structural characteristics of voltage clamping unit 1). The clamped voltage is then transmitted to voltage comparison unit 2, which compares the clamped voltage with a preset voltage. If the clamped voltage is greater than the preset voltage, indicating an overvoltage, voltage comparison unit 2 outputs a high level, turning off the first switch unit and implementing overvoltage protection. If the clamped voltage is less than or equal to the preset voltage, indicating no overvoltage, voltage comparison unit 2 outputs a low level, turning on the first switch unit.

[0050] Therefore, by providing the voltage clamping unit 1, the high voltage is clamped when a load dump event occurs, and the voltage comparison unit 2 and the first switch unit 3 are used to protect the electrical equipment in the entire path from overvoltage, thereby avoiding damage to the electrical equipment.

[0051] In summary, in this embodiment, the protection circuit includes: a voltage clamping unit, a voltage comparison unit, and a first switch unit; wherein one end of the voltage clamping unit is connected to the power input terminal, and the other end of the voltage clamping unit is connected to the first input terminal of the voltage comparison unit. The voltage clamping unit is used to clamp the voltage at the power input terminal to a first voltage and output it to the voltage comparison unit; the second input terminal of the voltage comparison unit is connected to a preset voltage reference point, and the output terminal of the voltage comparison unit is connected to the control terminal of the first switch unit. The voltage comparison unit is used to turn off the first switch unit when the first voltage is greater than the voltage input at the preset voltage reference point; the first end of the first switch unit is connected to the power input terminal, and the second end of the first switch unit is connected to the voltage output terminal. Thus, by providing the voltage clamping unit, the high voltage is clamped when a load dump event occurs, and overvoltage protection is implemented through the voltage comparison unit and the first switch unit, thereby preventing damage to the electrical equipment.

[0052] In the above Figure 1 Based on the corresponding embodiment, the embodiment of the present application also provides another protection circuit. Figure 2 A schematic diagram of the structure of another protection circuit provided in an embodiment of the present application.

[0053] like Figure 2As shown, the voltage clamping unit 1 is a TVS (Transient Voltage Suppressor) device D1. The TVS device D1 can clamp high voltage.

[0054] Continue to refer to Figure 2 In another embodiment of the present application, the voltage comparison unit 2 includes: an operational amplifier U1 , a first voltage divider circuit, and a voltage stabilizing circuit 22 .

[0055] One end of the first voltage divider circuit is the first input end of the voltage comparison unit 2, connected to the other end of the voltage clamping unit 1, the other end of the first voltage divider circuit is grounded, and the voltage dividing point of the first voltage divider circuit is connected to the non-inverting input end of the operational amplifier U1.

[0056] An input terminal of the voltage stabilizing circuit 22 is connected to a first terminal of the first switch unit 3 , and a first output terminal of the voltage stabilizing circuit 22 is connected to a positive power supply terminal of the operational amplifier U1 ;

[0057] The negative power supply terminal of the operational amplifier U1 is grounded. The inverting input terminal of the operational amplifier U1 is the second input terminal of the voltage comparison unit 2 and is used to connect to the second output terminal of the voltage stabilizing circuit 22. The output terminal of the operational amplifier U1 is the output terminal of the voltage comparison unit 2.

[0058] For example, the first voltage divider circuit includes: a first resistor R1 and a second resistor R2. The power input terminal is grounded through the first resistor R1 and the second resistor R2. The voltage dividing point of the first voltage divider circuit is between the first resistor R1 and the second resistor R2.

[0059] The voltage divided by the first voltage divider is input to PIN3 of the operational amplifier U1, and the preset voltage output by the voltage stabilizing circuit 22 is input to PIN4 of the operational amplifier U1.

[0060] If the voltage at PIN3 is greater than that at PIN4, indicating an overvoltage condition, PIN1 of operational amplifier U1 outputs a high level, turning off the first switch unit and implementing overvoltage protection. If the voltage at PIN3 is less than or equal to that at PIN4, indicating no overvoltage condition, PIN1 of operational amplifier U1 outputs a low level, turning on the first switch unit. This circuit design provides a voltage-regulated input and voltage comparison for the protection circuit while reducing costs.

[0061] The maximum overvoltage protection value of the entire protection circuit is determined by the parameters of the operational amplifier U1. The maximum overvoltage protection value can be adjusted by adjusting the operational amplifier U1.

[0062] In summary, in this embodiment, the voltage comparison unit includes: an operational amplifier, a first voltage divider circuit, and a voltage stabilizing circuit; one end of the first voltage divider circuit serves as the first input of the voltage comparison unit, connected to the other end of the voltage clamping unit; the other end of the first voltage divider circuit is grounded; and the voltage dividing point of the first voltage divider circuit is connected to the non-inverting input of the operational amplifier; the input of the voltage stabilizing circuit is connected to the first end of the first switching unit; the first output of the voltage stabilizing circuit is connected to the positive power supply of the operational amplifier; the negative power supply of the operational amplifier is grounded; the inverting input of the operational amplifier serves as the second input of the voltage comparison unit, connected to the second output of the voltage stabilizing circuit; and the output of the operational amplifier serves as the output of the voltage comparison unit. Thus, while reducing costs, the protection circuit is provided with a regulated voltage input and voltage comparison.

[0063] Continue to refer to Figure 2 In another embodiment of the present application, the voltage stabilizing circuit 22 includes: a current limiting resistor R3, a voltage stabilizing diode D2 and a second voltage divider circuit. The first end of the first switch unit 3 is connected to the anode of the voltage stabilizing diode D2 through the current limiting resistor, the cathode of the voltage stabilizing diode D2 is grounded, and the anode of the voltage stabilizing diode D2 is the first output end of the voltage stabilizing circuit 22.

[0064] The anode of the voltage stabilizing diode D2 is also grounded through a second voltage dividing circuit, and the voltage dividing point of the second voltage dividing circuit is the second output end of the voltage stabilizing circuit 22 .

[0065] For example, the second voltage divider circuit includes: a fourth resistor R4 and a fifth resistor R5. The anode of the Zener diode D2 is grounded through the fourth resistor R4 and the fifth resistor R5. The voltage dividing point of the second voltage divider circuit is between the fourth resistor R4 and the fifth resistor R5.

[0066] Therefore, the current limiting resistor R3 performs current limiting protection on the voltage regulator diode D2, and a voltage regulated output is achieved through the voltage regulator diode D2 and the voltage divider circuit, thereby providing a stable preset voltage for the operational amplifier.

[0067] In summary, in this embodiment, the voltage-stabilizing circuit includes: a current-limiting resistor, a voltage-stabilizing diode, and a second voltage-divider circuit. The first end of the first switch unit is connected to the anode of the voltage-stabilizing diode via the current-limiting resistor, the cathode of the voltage-stabilizing diode is grounded, and the anode of the voltage-stabilizing diode serves as the first output end of the voltage-stabilizing circuit. The anode of the voltage-stabilizing diode is also grounded via the second voltage-divider circuit, and the voltage-dividing point of the second voltage-divider circuit serves as the second output end of the voltage-stabilizing circuit. Thus, the voltage-stabilizing diode and the voltage-divider circuit achieve a regulated output, providing a stable preset voltage for the operational amplifier.

[0068] In the above Figure 1 On the basis of the corresponding embodiment, the embodiment of the present application also provides another protection circuit. Figure 3 A structural diagram of another protection circuit provided in an embodiment of the present application.

[0069] like Figure 3 As shown, the protection circuit also includes: a switch circuit 4, the control end of the switch circuit 4 is connected to the output end of the voltage comparison unit 2, the first end of the switch circuit 4 is connected to the first end of the first switch unit 3, the second end of the switch circuit 4 is grounded, and the third end of the switch circuit 4 is connected to the control end of the first switch unit 3.

[0070] By providing a switch circuit 4, the high / low level output by the voltage comparison unit 2 can more accurately control the first switch unit 3. When the voltage comparison unit 2 outputs a high level, the switch circuit 4 is turned on, controlling the first switch unit 3 to be turned off. When the voltage comparison unit 2 outputs a low level, the switch circuit 4 is turned off, controlling the first switch unit 3 to be turned on.

[0071] In summary, in this embodiment, the protection circuit further includes a switch circuit, wherein a control terminal of the switch circuit is connected to the output terminal of the voltage comparison unit, a first terminal of the switch circuit is connected to the first terminal of the first switch unit, a second terminal of the switch circuit is grounded, and a third terminal of the switch circuit is connected to the control terminal of the first switch unit. Thus, by providing the switch circuit, the high / low level output by the voltage comparison unit can be used to more accurately control the first switch unit.

[0072] Continue to refer to Figure 2 In another embodiment of the present application, the switch circuit 4 includes: a third voltage divider circuit, a fourth voltage divider circuit, a first switch tube Q1 and a second switch tube Q2.

[0073] One end of the third voltage-dividing circuit is the control end of the switch circuit 4 , the other end of the third voltage-dividing circuit is grounded, and a voltage dividing point of the third voltage-dividing circuit is connected to the control end of the first switch tube Q1 .

[0074] The first end of the first switch unit 3 is also grounded through a fourth voltage-dividing circuit. The voltage-dividing point of the fourth voltage-dividing circuit is respectively connected to the first end of the first switch tube Q1 and the control end of the second switch tube Q2. The second end of the first switch tube Q1 and the second end of the second switch tube Q2 are both grounded. The first end of the second switch tube Q2 serves as the third end of the switch circuit 4.

[0075] When the voltage comparison unit 2 outputs a high level, the first switch tube Q1 is turned on, and the second switch tube Q2 is turned off, thereby controlling the first switch unit 3 to be turned off. When the voltage comparison unit 2 outputs a low level, the first switch tube Q1 is turned off, and the second switch tube Q2 is turned on, thereby controlling the first switch unit 3 to be turned on.

[0076] For example, the third voltage divider circuit includes: a sixth resistor R6 and a seventh resistor R7. The control end of the switch circuit 4 is grounded through the sixth resistor R6 and the seventh resistor R7. The voltage dividing point of the third voltage divider circuit is the position between the sixth resistor R6 and the seventh resistor R7.

[0077] For example, the fourth voltage divider circuit includes: an eighth resistor R8 and a ninth resistor R9. The control end of the switch circuit 4 is grounded through the eighth resistor R8 and the ninth resistor R9. The voltage dividing point of the fourth voltage divider circuit is between the eighth resistor R8 and the ninth resistor R9.

[0078] Continue to refer to Figure 2 In another embodiment of the present application, the first switch tube Q1 and the second switch tube Q2 are both NPN transistors, the first ends of the first switch tube Q1 and the second switch tube Q2 are collectors of the NPN transistors, the second ends of the first switch tube Q1 and the second switch tube Q2 are emitters of the NPN transistors, and the third ends of the first switch tube Q1 and the second switch tube Q2 are bases of the NPN transistors.

[0079] In the above Figure 1 On the basis of the corresponding embodiment, the embodiment of the present application further provides a protection circuit. Figure 4 A structural diagram of another protection circuit provided in the embodiment of the present application is shown below. Figure 4 As shown, the protection circuit further includes: a second switch unit 5 .

[0080] A first end of the second switch unit 5 is connected to the power input end, a second end of the second switch unit 5 is connected to the first end of the first switch unit 3 , and a control end of the second switch unit 5 is grounded.

[0081] In this embodiment, the main current of the protection circuit flows to: the power input terminal, the second switch unit 5, the first switch unit 3, and the voltage output terminal.

[0082] When the power supply is connected in a positive direction, the second switch unit 5 is turned on, and the main circuit of the protection circuit is turned on. When the power supply is connected in a reverse direction, the second switch unit 5 is turned off, and the main circuit of the protection circuit is turned off. Thus, the reverse connection protection is achieved by providing the second switch unit 5.

[0083] In summary, in this embodiment, the protection circuit further includes a second switch unit; a first terminal of the second switch unit is connected to the power input terminal, a second terminal of the second switch unit is connected to the first terminal of the first switch unit, and a control terminal of the second switch unit is grounded. Thus, reverse connection protection is achieved by providing the second switch unit.

[0084] exist Figure 4 On the basis of the corresponding embodiment, in another embodiment of the present application, the first switch unit 3 is a first PMOS switch unit, and the second switch unit 5 is a second PMOS switch unit.

[0085] The first end of the first switch unit 3 is the source (S) of the first PMOS switch unit, the second end of the first switch unit 3 is the drain (D) of the first PMOS switch unit, and the control end of the first switch unit 3 is the gate (G) of the first PMOS switch unit.

[0086] The first end of the second switch unit 5 is the drain (D) of the second PMOS switch unit, the second end of the second switch unit 5 is the source (S) of the second PMOS switch unit, and the control end of the second switch unit 5 is the gate (G) of the second PMOS switch unit. By providing the first PMOS switch unit and the second PMOS switch unit, control accuracy is improved.

[0087] Continue to refer to Figure 2 In another embodiment of the present application, the second switch unit 5 further includes: a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first capacitor C1, and a second capacitor C2.

[0088] One end of the tenth resistor R10 is connected to the power input end through the first capacitor C1, the other end of the tenth resistor R10 is connected to the source of the second PMOS switch unit in parallel with the second capacitor C2 through the eleventh resistor R11, and the other end of the tenth resistor R10 is also connected to the gate of the second PMOS switch unit through the twelfth resistor R12.

[0089] When the power supply is connected to the positive terminal, the positive terminal of the power supply is connected to the power output terminal, and the negative terminal of the power supply is connected to the voltage output terminal through the power-consuming device. The voltage is transmitted to the source and gate of the second PMOS switch unit through the first capacitor C1, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12, respectively. Since the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12 are different, the voltage difference between the source and gate of the second PMOS switch unit satisfies the conduction condition of the second PMOS switch unit, causing the second PMOS switch unit to conduct.

[0090] When the power supply is reversed, the negative electrode of the power supply is connected to the power output terminal, and the positive electrode of the power supply is connected to the voltage output terminal through the power-consuming device. A low level (voltage of 0) is transmitted to the gate of the second PMOS switch unit through the first capacitor C1, the tenth resistor R10, and the twelfth resistor R12. Meanwhile, the positive electrode of the power supply transmits a high level to the source of the second PMOS switch unit through the first switch unit 3. As a result, the voltage difference between the source and gate of the second PMOS switch unit is large, meeting the shutdown condition of the second PMOS switch unit and causing the second PMOS switch unit to shut down. Thus, reverse connection protection is achieved.

[0091] On the basis of the above embodiments, the embodiments of the present application further provide a vehicle power system. The vehicle power system.

[0092] The invention comprises a vehicle power supply device, a vehicle electrical device, and a protection circuit according to any of the above embodiments; the vehicle power supply device is connected to the vehicle electrical device via the protection circuit. Thus, by providing a voltage clamping unit, when a load dump event occurs, the high voltage is clamped to achieve overvoltage protection, thereby preventing damage to the electrical device.

[0093] For example, the vehicle electrical equipment includes at least 24V electrical equipment.

[0094] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application. It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A protection circuit, characterized in that: The protection circuit includes: a voltage clamping unit, a voltage comparison unit and a first switch unit; Wherein, one end of the voltage clamping unit is connected to the power input end, and the other end of the voltage clamping unit is connected to the first input end of the voltage comparison unit, and the voltage clamping unit is used to clamp the voltage of the power input end to a first voltage and output it to the voltage comparison unit; The second input terminal of the voltage comparison unit is connected to a preset voltage reference point, the output terminal of the voltage comparison unit is connected to the control terminal of the first switch unit, and the voltage comparison unit is used to turn off the first switch unit when the first voltage is greater than the voltage inputted at the preset voltage reference point; A first end of the first switch unit is connected to the power input end, and a second end of the first switch unit is connected to the voltage output end; The voltage comparison unit includes: an operational amplifier, a first voltage divider circuit, and a voltage stabilizing circuit; One end of the first voltage divider circuit is the first input end of the voltage comparison unit, connected to the other end of the voltage clamping unit, the other end of the first voltage divider circuit is grounded, and the voltage dividing point of the first voltage divider circuit is connected to the non-inverting input end of the operational amplifier; The input end of the voltage stabilizing circuit is connected to the first end of the first switch unit, and the first output end of the voltage stabilizing circuit is connected to the positive power supply end of the operational amplifier; The negative power supply terminal of the operational amplifier is grounded, the inverting input terminal of the operational amplifier is the second input terminal of the voltage comparison unit, and is used to connect the second output terminal of the voltage stabilizing circuit, and the output terminal of the operational amplifier is the output terminal of the voltage comparison unit.

2. The protection circuit according to claim 1, wherein: The voltage clamping unit is a transient voltage suppression device.

3. The protection circuit according to claim 1, wherein: The voltage stabilizing circuit includes: a current limiting resistor, a voltage stabilizing diode and a second voltage divider circuit, the first end of the first switch unit is connected to the anode of the voltage stabilizing diode through the current limiting resistor, the cathode of the voltage stabilizing diode is grounded, and the anode of the voltage stabilizing diode is the first output end of the voltage stabilizing circuit; The anode of the voltage stabilizing diode is also grounded through the second voltage dividing circuit, and the voltage dividing point of the second voltage dividing circuit is the second output end of the voltage stabilizing circuit.

4. The protection circuit according to claim 1, wherein: The protection circuit also includes: a switching circuit, wherein the control end of the switching circuit is connected to the output end of the voltage comparison unit, the first end of the switching circuit is connected to the first end of the first switching unit, the second end of the switching circuit is grounded, and the third end of the switching circuit is connected to the control end of the first switching unit.

5. The protection circuit according to claim 4, characterized in that: The switch circuit includes: a third voltage divider circuit, a fourth voltage divider circuit, a first switch tube and a second switch tube; One end of the third voltage divider circuit is the control end of the switch circuit, the other end of the third voltage divider circuit is grounded, and the voltage dividing point of the third voltage divider circuit is connected to the control end of the first switch tube; The first end of the first switch unit is also grounded through the fourth voltage-dividing circuit, the voltage-dividing point of the fourth voltage-dividing circuit is respectively connected to the first end of the first switch tube and the control end of the second switch tube, the second end of the first switch tube and the second end of the second switch tube are both grounded, and the first end of the second switch tube is the third end of the switch circuit.

6. The protection circuit according to claim 5, characterized in that: The first switching tube and the second switching tube are both NPN transistors, the first ends of the first switching tube and the second switching tube are the collectors of the NPN transistors, the second ends of the first switching tube and the second switching tube are the emitters of the NPN transistors, and the third ends of the first switching tube and the second switching tube are the bases of the NPN transistors.

7. The protection circuit according to claim 1, wherein: The protection circuit further includes: a second switch unit; A first end of the second switch unit is connected to the power input end, a second end of the second switch unit is connected to the first end of the first switch unit, and a control end of the second switch unit is grounded.

8. The protection circuit according to claim 7, wherein: The first switch unit is a first PMOS switch unit, and the second switch unit is a second PMOS switch unit; The first end of the first switch unit is the source of the first PMOS switch unit, the second end of the first switch unit is the drain of the first PMOS switch unit, and the control end of the first switch unit is the gate of the first PMOS switch unit; The first end of the second switch unit is the drain of the second PMOS switch unit, the second end of the second switch unit is the source of the second PMOS switch unit, and the control end of the second switch unit is the gate of the second PMOS switch unit.

9. A vehicle power system, characterized in that: include: Vehicle power supply equipment, vehicle electrical equipment, and the protection circuit according to any one of claims 1 to 8 above; The vehicle power supply device is connected to the vehicle electrical device via the protection circuit.

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