Overvoltage protection circuit

Abstract

The utility model relates to the technical field of overvoltage protection, and provides an overvoltage protection circuit, which comprises a first switch unit, a voltage comparison unit and a second switch unit, the first end of the first switch unit is connected with the first end of the voltage comparison unit, the second end of the first switch unit is connected with the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected with the first end of the second switch unit, and the second end of the second switch unit is connected with the second end of the first switch unit. The third end of the second switch unit is connected with the third end of the first switch unit; when the voltage of the first end of the first switch unit is larger than or equal to the voltage of the second end, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is connected. When the voltage of the first end of the first switch unit is smaller than the voltage of the second end of the first switch unit, the third end of the voltage comparison unit outputs a switch-on signal, and the second switch unit is switched on and outputs a signal for switching off the first switch unit.

Description

Technical Field

[0001] The utility model relates to the technical field of overvoltage protection, and more specifically, to an overvoltage protection circuit. Background Art

[0002] Overvoltage protection circuits are crucial safety features in electronic devices. Their primary purpose is to protect circuits from damage caused by excessive voltage. With the continuous advancement of electronic technology, the design of overvoltage protection circuits has also been continuously developed and improved to meet the needs of various application scenarios.

[0003] Take the automotive industry, for example. With its rapid development, automotive electronics are playing an increasingly important role in ensuring driver comfort, and are receiving increasing attention from automakers and infotainment system suppliers. Most in-vehicle infotainment systems now include features such as mobile phone connectivity and fast charging. According to research, high-end vehicles now have more than five USB ports, a testament to the growing breadth of USB applications. However, this widespread adoption has also led to various practical issues, such as compatibility and fault tolerance. For example, if a power bank's power supply is connected to an entertainment system's USB port, or a laptop's PD is simultaneously connected to an entertainment system's USB port, the output voltage of the USB port may be lower than the input voltage, resulting in voltage / current reverse flow. Even if the input voltage exceeds the maximum withstand voltage of the USB interface circuit, this can cause malfunctioning of the USB, the entire system, or even damage the system, impacting vehicle safety and user experience.

[0004] Therefore, the prior art proposes an overvoltage protection circuit to protect the circuit from damage caused by excessively high voltage. However, the prior art overvoltage protection circuit has difficulty in identifying the external voltage and quickly performing corresponding protection, and thus cannot achieve effective overvoltage protection. Utility Model Content

[0005] In order to overcome the defects of the above-mentioned prior art in that it is difficult to identify the external voltage and quickly perform corresponding protection, the utility model provides an overvoltage protection circuit that can quickly identify the external voltage and quickly perform corresponding protection.

[0006] In order to solve the above technical problems, the technical solutions of the present utility model are as follows:

[0007] An overvoltage protection circuit includes a first switch unit, a voltage comparison unit and a second switch unit;

[0008] The first end of the first switch unit is connected to the first end of the voltage comparison unit, the second end of the first switch unit is connected to the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to the second end of the first switch unit, and the third end of the second switch unit is connected to the third end of the first switch unit.

[0009] When the voltage at the first end of the first switch unit is greater than or equal to the voltage at the second end thereof, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is turned on;

[0010] When the voltage at the first end of the first switch unit is lower than the voltage at the second end thereof, the third end of the voltage comparison unit outputs a turn-on signal, and the second switch unit turns on and outputs a signal to turn off the first switch unit.

[0011] Compared with the prior art, the beneficial effects of the technical solution of the utility model are:

[0012] The present application utilizes a first switch unit, a voltage comparison unit, and a second switch unit for overvoltage protection. The voltage comparison unit is used to compare the voltage between the first end and the second end of the first switch unit. When the voltage is normal, the voltage of the first end of the first switch unit is greater than or equal to the voltage of its second end, the second switch unit is disconnected, and the voltage difference between the third end and the second end of the first switch unit is greater than the voltage that makes the first switch unit turn on. The first switch unit is turned on, and current flows from the first end to the second end of the first switch unit; when an overvoltage phenomenon occurs, the voltage of the first end of the first switch unit is less than the voltage of the second end of the first switch unit, the second switch unit is turned on, the voltage difference between the third end and the second end of the switch unit is less than or equal to the turn-on voltage of the first switch unit, the first switch unit is disconnected, and current cannot flow from the first end to the second end of the first switch unit, thereby achieving the purpose of overvoltage power off, and being able to quickly identify external voltage and quickly perform corresponding protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the first structure of the overvoltage protection circuit proposed in Example 1;

[0014] Figure 2 This is a second structural diagram of the overvoltage protection circuit proposed in Example 1;

[0015] Figure 3 This is a third structural diagram of the overvoltage protection circuit proposed in Example 1. DETAILED DESCRIPTION

[0016] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting this patent;

[0017] In order to better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size;

[0018] It is understandable to those skilled in the art that some well-known structures and descriptions thereof may be omitted in the drawings.

[0019] The technical solution of the present utility model is further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] This embodiment provides an overvoltage protection circuit. Figure 1 This is a schematic diagram of the first structure of the overvoltage protection circuit proposed in this embodiment.

[0022] like Figure 1 As shown, this embodiment provides an overvoltage protection circuit, including a first switch unit, a voltage comparison unit and a second switch unit;

[0023] The first end of the first switch unit is connected to the first end of the voltage comparison unit, the second end of the first switch unit is connected to the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to the second end of the first switch unit, and the third end of the second switch unit is connected to the third end of the first switch unit.

[0024] When the voltage at the first end of the first switch unit is greater than or equal to the voltage at the second end thereof, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is turned on;

[0025] When the voltage at the first end of the first switch unit is lower than the voltage at the second end thereof, the third end of the voltage comparison unit outputs a turn-on signal, and the second switch unit turns on and outputs a signal to turn off the first switch unit.

[0026] In the specific implementation process, the present application utilizes a first switch unit, a voltage comparison unit and a second switch unit for overvoltage protection. The voltage comparison unit is used to compare the voltage between the first end and the second end of the first switch unit. When the voltage is normal, the voltage of the first end of the first switch unit is greater than or equal to the voltage of its second end, the second switch unit is disconnected, and the voltage difference between the third end and the second end of the first switch unit is greater than the voltage that makes the first switch unit turn on. The first switch unit is turned on, and the current flows from the first end to the second end of the first switch unit; when an overvoltage phenomenon occurs, the voltage of the first end of the first switch unit is less than the voltage of its second end, the second switch unit is turned on, the voltage difference between the third end and the second end of the switch unit is less than or equal to the turn-on voltage of the first switch unit, the first switch unit is disconnected, and the current cannot flow from the first end to the second end of the first switch unit, thereby achieving the purpose of overvoltage power off, and being able to quickly identify the external voltage and quickly perform corresponding protection.

[0027] In an optional embodiment, the first switch unit includes a first switch element Q1 and a resistor R1;

[0028] The first end, the second end and the third end of the first switch unit are respectively the first end, the second end and the third end of the first switch element Q1, and the third end of the first switch unit is connected to the first end of the resistor R1, and the second end of the resistor R1 is grounded.

[0029] In an optional embodiment, the first switching element Q1 includes a PMOS tube;

[0030] The first end, the second end and the third end of the first switch element Q1 are the drain, the source and the gate of the PMOS tube respectively.

[0031] In an optional embodiment, the voltage comparison unit includes a comparator;

[0032] The first end, the second end and the third end of the voltage comparison unit are respectively the inverting input port, the non-inverting input port and the output port of the comparator CT.

[0033] Example 2

[0034] This embodiment makes improvements based on the overvoltage protection circuit proposed in Embodiment 1.

[0035] This embodiment provides an overvoltage protection circuit, including a first switch unit, a voltage comparison unit, and a second switch unit;

[0036] The first end of the first switch unit is connected to the first end of the voltage comparison unit, the second end of the first switch unit is connected to the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to the second end of the first switch unit, and the third end of the second switch unit is connected to the third end of the first switch unit.

[0037] When the voltage at the first end of the first switch unit is greater than or equal to the voltage at the second end thereof, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is turned on;

[0038] When the voltage at the first end of the first switch unit is lower than the voltage at the second end thereof, the third end of the voltage comparison unit outputs a turn-on signal, and the second switch unit turns on and outputs a signal to turn off the first switch unit.

[0039] In the specific implementation process, the present application utilizes a first switch unit, a voltage comparison unit and a second switch unit for overvoltage protection. The voltage comparison unit is used to compare the voltage between the first end and the second end of the first switch unit. When the voltage is normal, the voltage of the first end of the first switch unit is greater than or equal to the voltage of its second end, the second switch unit is disconnected, and the voltage difference between the third end and the second end of the first switch unit is greater than the voltage that makes the first switch unit turn on. The first switch unit is turned on, and the current flows from the first end to the second end of the first switch unit; when an overvoltage phenomenon occurs, the voltage of the first end of the first switch unit is less than the voltage of its second end, the second switch unit is turned on, the voltage difference between the third end and the second end of the switch unit is less than or equal to the turn-on voltage of the first switch unit, the first switch unit is disconnected, and the current cannot flow from the first end to the second end of the first switch unit, thereby achieving the purpose of overvoltage power off, and being able to quickly identify the external voltage and quickly perform corresponding protection.

[0040] In an optional embodiment, the second switch unit includes a second switch element Q2, a third switch element Q3, a resistor R2 and a resistor R5;

[0041] The first end, the second end and the third end of the second switch unit are respectively the first end of the third switch element Q3, the third end of the second switch element Q2 and the second end of the second switch element Q2;

[0042] A first end of the resistor R5 is grounded, a second end of the resistor R5 is connected to a first end of the third switch element Q3, a second end of the third switch element Q3 is grounded, a third end of the third switch element Q3 is connected to a first end of the resistor R2 and a first end of the second switch element Q2, and a second end of the resistor R2 is connected to a third end of the second switch element Q2.

[0043] In an optional embodiment, the second switching element Q2 is an N-type transistor;

[0044] The third switch element Q3 is a P-type transistor;

[0045] The first end, the second end and the third end of the second switching element Q2 are respectively the base, the collector and the emitter of the N-type transistor;

[0046] The first end, the second end and the third end of the third switch element Q3 are respectively the base, the emitter and the collector of a P-type transistor.

[0047] In an optional embodiment, the third end of the third switch element Q3 is connected to the first end of the resistor R2 and the first end of the second switch element Q2 through the resistor R3.

[0048] As an exemplary illustration, the resistor R3 plays a role of current limiting.

[0049] In an optional embodiment, the voltage comparison unit is connected to the first end of the second switch unit through a resistor R4.

[0050] As an exemplary illustration, the resistor R4 serves to limit the current.

[0051] It can be understood that the overvoltage protection circuit of this embodiment is an improvement on the overvoltage protection circuit of Embodiment 1. The options in Embodiment 1 are also applicable to this embodiment, so they will not be described again here.

[0052] Example 3

[0053] This embodiment makes improvements based on the overvoltage protection circuits proposed in Embodiments 1 and 2.

[0054] This embodiment provides an overvoltage protection circuit, including a first switch unit, a voltage comparison unit, and a second switch unit;

[0055] The first end of the first switch unit is connected to the first end of the voltage comparison unit, the second end of the first switch unit is connected to the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to the second end of the first switch unit, and the third end of the second switch unit is connected to the third end of the first switch unit.

[0056] When the voltage at the first end of the first switch unit is greater than or equal to the voltage at the second end thereof, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is turned on;

[0057] When the voltage at the first end of the first switch unit is lower than the voltage at the second end thereof, the third end of the voltage comparison unit outputs a turn-on signal, and the second switch unit turns on and outputs a signal to turn off the first switch unit.

[0058] In the specific implementation process, the present application utilizes a first switch unit, a voltage comparison unit and a second switch unit for overvoltage protection. The voltage comparison unit is used to compare the voltage between the first end and the second end of the first switch unit. When the voltage is normal, the voltage of the first end of the first switch unit is greater than or equal to the voltage of its second end, the second switch unit is disconnected, and the voltage difference between the third end and the second end of the first switch unit is greater than the voltage that makes the first switch unit turn on. The first switch unit is turned on, and the current flows from the first end to the second end of the first switch unit; when an overvoltage phenomenon occurs, the voltage of the first end of the first switch unit is less than the voltage of its second end, the second switch unit is turned on, the voltage difference between the third end and the second end of the switch unit is less than or equal to the turn-on voltage of the first switch unit, the first switch unit is disconnected, and the current cannot flow from the first end to the second end of the first switch unit, thereby achieving the purpose of overvoltage power off, and being able to quickly identify the external voltage and quickly perform corresponding protection.

[0059] In an optional embodiment, the overvoltage protection circuit further includes a power input unit, a voltage stabilization unit, and a power output unit;

[0060] Wherein, the power input unit is connected to the first end of the first switch unit via the voltage stabilizing unit;

[0061] The power output unit is connected to the second end of the first switch unit.

[0062] As an example, Figure 2 This is a second schematic diagram of the overvoltage protection circuit proposed in this embodiment; Figure 2 A schematic diagram of an overvoltage protection circuit having a power input unit, a voltage regulation unit, and a power output unit is shown.

[0063] In an optional embodiment, the voltage stabilizing unit includes a BUCK circuit.

[0064] As an example, Figure 3 This is a third schematic diagram of the overvoltage protection circuit proposed in this embodiment; Figure 3 As shown, the power input unit includes a vehicle battery; the BUCK circuit is arranged inside a USB charger (Charger), and the BUCK circuit can interact with the MCU; the power output unit includes a USB connector (Connector); the second end of the first switch unit is also connected to a grounding capacitor.

[0065] As an example, the vehicle battery input voltage range is: 9V~16V.

[0066] As an example, the voltage is converted to USB standard voltage (4.97V~5.25V) through the BUCK circuit.

[0067] As an exemplary illustration, G represents a gate, S represents a source, and D represents a drain.

[0068] When no overvoltage occurs and the USB Charger is turned on, the parasitic diode of MOS transistor Q1 conducts, forming a loop at the interface. The potential of source S is approximately -0.7V, the buck output voltage. Due to the pull-down resistor R1, the potential of gate G approaches 0V. Therefore, VGS>VGS(th), and DS of PMOS (Q1) conducts. Here, VGS represents the gate voltage relative to the source, and VGS(th) represents the turn-on voltage of Q1. Because DS is on, the voltage at drain D is ≥ the voltage at gate S. The negative input terminal (inverting input port) of the comparator is ≥ the positive input terminal (non-inverting input port), so the output is low. Due to the low input of transistor Q3, the transistor Q3 is disconnected through the current-limiting resistor R4 and the pull-down resistor R5. Because transistor Q3 is disconnected, the base of N-type transistor Q2 is pulled up to VBUS through resistor R4, and transistor Q2 is disconnected.

[0069] As an example, when an overvoltage occurs, take the overvoltage at the USB port as an example. When an overvoltage occurs at the USB port, the interface voltage is greater than the output voltage of the USB Charger. At this time, the negative electrode of the comparator input terminal is less than the positive electrode, and the comparator outputs a high level. The comparator outputs a high level, and the transistor Q3 is turned on through the current limiting resistor R4 and the pull-down resistor R5. When Q3 is turned on, the base of the N-type transistor Q2 is generated to generate a current through the current limiting resistor R3, causing the CE of the transistor Q2 to be turned on. After the transistor Q2 is turned on, the gate G potential of the MOS tube is pulled up. At this time, VGS is less than VGS(th), and the MOS tube Q1 is disconnected. Because the MOS tube Q1 is disconnected, the USB Charger is disconnected from the USB interface, thereby forming a protection.

[0070] It can be understood that the overvoltage protection circuit of this embodiment improves the overvoltage protection circuits of Embodiments 1 and 2. The options in Embodiments 1 and 2 are also applicable to this embodiment, so they will not be described again here.

[0071] The same or similar reference numerals correspond to the same or similar components;

[0072] The terms used in the drawings to describe positional relationships are for illustrative purposes only and should not be construed as limiting this patent;

[0073] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. An overvoltage protection circuit, characterized in that: comprising a first switching unit, a voltage comparison unit and a second switching unit; The first end of the first switch unit is connected to the first end of the voltage comparison unit, the second end of the first switch unit is connected to the second end of the voltage comparison unit, the third end of the voltage comparison unit is connected to the first end of the second switch unit, the second end of the second switch unit is connected to the second end of the first switch unit, and the third end of the second switch unit is connected to the third end of the first switch unit. When the voltage at the first end of the first switch unit is greater than or equal to the voltage at the second end thereof, the third end of the voltage comparison unit outputs a disconnection signal, the second switch unit is disconnected, and the first switch unit is turned on; When the voltage at the first end of the first switch unit is lower than the voltage at the second end thereof, the third end of the voltage comparison unit outputs a turn-on signal, and the second switch unit turns on and outputs a signal to turn off the first switch unit.

2. The overvoltage protection circuit according to claim 1, wherein: The first switch unit includes a first switch element Q1 and a resistor R1; The first end, the second end and the third end of the first switch unit are respectively the first end, the second end and the third end of the first switch element Q1, and the third end of the first switch unit is connected to the first end of the resistor R1, and the second end of the resistor R1 is grounded.

3. The overvoltage protection circuit according to claim 2, characterized in that: The first switching element Q1 includes a PMOS tube; The first end, the second end and the third end of the first switch element Q1 are the drain, the source and the gate of the PMOS tube respectively.

4. The overvoltage protection circuit according to claim 1, wherein: The voltage comparison unit includes a comparator; The first end, the second end and the third end of the voltage comparison unit are respectively the inverting input port, the non-inverting input port and the output port of the comparator CT.

5. The overvoltage protection circuit according to claim 1, wherein: The second switch unit includes a second switch element Q2, a third switch element Q3, a resistor R2 and a resistor R5; The first end, the second end and the third end of the second switch unit are respectively the first end of the third switch element Q3, the third end of the second switch element Q2 and the second end of the second switch element Q2; A first end of the resistor R5 is grounded, a second end of the resistor R5 is connected to a first end of the third switch element Q3, a second end of the third switch element Q3 is grounded, a third end of the third switch element Q3 is connected to a first end of the resistor R2 and a first end of the second switch element Q2, and a second end of the resistor R2 is connected to a third end of the second switch element Q2.

6. The overvoltage protection circuit according to claim 5, characterized in that: The second switching element Q2 is an N-type transistor; The third switch element Q3 is a P-type transistor; The first end, the second end and the third end of the second switching element Q2 are respectively the base, the collector and the emitter of the N-type transistor; The first end, the second end and the third end of the third switch element Q3 are respectively the base, the emitter and the collector of a P-type transistor.

7. The overvoltage protection circuit according to claim 5 or 6, characterized in that: The third end of the third switch element Q3 is connected to the first end of the resistor R2 and the first end of the second switch element Q2 through the resistor R3.

8. The overvoltage protection circuit according to any one of claims 1 to 6, characterized in that: The voltage comparison unit is connected to the second switch unit via a resistor R4.

9. The overvoltage protection circuit according to any one of claims 1 to 6, characterized in that: The overvoltage protection circuit further includes a power input unit, a voltage stabilizing unit and a power output unit; Wherein, the power input unit is connected to the first end of the first switch unit via the voltage stabilizing unit; The power output unit is connected to the second end of the first switch unit.

10. The overvoltage protection circuit according to claim 9, characterized in that: The voltage stabilizing unit includes a BUCK circuit.

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