An overvoltage protection circuit

Abstract

This utility model relates to the field of overvoltage protection technology and discloses an overvoltage protection circuit, including a voltage detection unit, a reference voltage generation unit, a comparison unit, a drive unit, and a switch unit. The voltage detection unit detects the battery voltage and inputs the detected voltage to the positive input terminal of the comparison unit. The reference voltage generation unit generates a reference voltage that is input to the negative input terminal of the comparison unit. The drive unit controls the switch unit to turn on and off based on the output signal of the comparison unit, and the battery voltage is input to the input terminal of the switch unit. In use, when the battery voltage is too high, the comparison unit outputs a high-level signal, and the drive unit controls the switch unit to turn off, so the battery voltage will not be input to the load through the switch unit. When the battery voltage returns to normal, the comparison unit outputs a low-level signal, and the drive unit controls the switch unit to turn on, so the battery voltage is input to the load through the switch unit to supply power. This achieves both overvoltage protection and power supply self-recovery.

Description

Technical Field

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

[0002] In the field of power electronics, batteries are mostly used for power supply. For example, the ECU of a car draws power from the battery. However, due to the inductive coil loads connected to the battery, such as solenoid valves and motors, the battery voltage may rise. This rise in battery voltage will cause the current of the electronic devices that are powered to increase, affecting the normal operation of the electronic devices.

[0003] To suppress overvoltage, a TVS (Transient Voltage Suppressor) device is usually placed at the power port of the car's ECU. However, the TVS device can only suppress transient or short-term high voltage. Since the battery is unpredictable when high voltage changes suddenly, the ECU is at high risk of damage when it operates under various complex conditions for a long time. Utility Model Content

[0004] In view of the shortcomings of the prior art, the present invention provides an overvoltage protection circuit for disconnecting the battery from the load when the battery voltage is too high, and reconnecting the battery to the load when the battery voltage returns to normal.

[0005] To solve the above technical problems, this utility model provides the following technical solution: an overvoltage protection circuit, including a voltage detection unit, a reference voltage generation unit, a comparison unit, a driving unit, and a switching unit; The voltage detection unit is used to detect the battery voltage and input the detected voltage to the positive input terminal of the comparison unit; The reference voltage generation unit generates a reference voltage based on the battery voltage, which is input to the negative input terminal of the comparison unit. The drive unit is electrically connected to the output terminal of the comparator unit, and controls the switching unit to open or close based on the signal output from the output terminal of the comparator unit. The input terminal of the switch unit is used to input the battery voltage.

[0006] In one embodiment, the driving unit drives the switching unit to turn on when it outputs a low-level signal at the output terminal of the comparison unit, and drives the switching unit to turn off when it outputs a high-level signal at the output terminal of the comparison unit.

[0007] In one embodiment, the voltage detection unit includes resistors R1 and R2. One end of resistor R1 is used to input the battery voltage, and the other end of resistor R1 is electrically connected to the positive input terminal of the comparison unit and grounded through the battery R2.

[0008] In one embodiment, the reference voltage generating unit includes a resistor R3 and a Zener diode V1. One end of the resistor R3 is used to input the battery voltage, and the other end of the resistor R3 is electrically connected to the negative input terminal of the comparator unit and the cathode of the Zener diode V1. The anode of the Zener diode V1 is grounded.

[0009] In one embodiment, the comparison unit includes a comparator CMP1 and a resistor R4. The negative input terminal of the comparator CMP1 is the negative input terminal of the comparison unit, and the positive input terminal of the comparator CMP1 is the positive input terminal of the comparison unit. The comparator CMP1 is connected to the output terminal of the comparator unit through the resistor R4. The output terminal of the comparator CMP1 is the output terminal of the comparison unit.

[0010] In one embodiment, the driving unit includes resistors R5 and R6, transistors Q1 and Q2. The base of transistor Q1 is electrically connected to the output terminal of the comparator unit, the collector of transistor Q1 is electrically connected to the base of transistor Q2, the emitter of transistor Q1 is grounded, the emitter of transistor Q2 is electrically connected to one end of resistor R5 for inputting battery voltage, and the collector of transistor Q2 is electrically connected to the control terminal of the switching unit and the other end of resistor R5, and is grounded through resistor R6.

[0011] In one embodiment, the transistor Q1 is an NPN transistor.

[0012] In one embodiment, the transistor Q2 is a PNP transistor.

[0013] In one embodiment, the switching unit includes a switching transistor Q3, the input terminal of the switching transistor Q3 is the input terminal of the switching unit, the control terminal of the switching transistor Q3 is the control terminal of the switching unit, and the output terminal of the switching transistor Q3 is the output terminal of the switching unit.

[0014] In one embodiment, the switch Q3 is a PMOS transistor, with the source of the PMOS transistor being the input terminal of the switch Q3, the gate of the PMOS transistor being the control terminal of the switch Q3, and the drain of the PMOS transistor being the output terminal of the switch Q3.

[0015] The advantages of this invention compared to the prior art are as follows: In actual use, when the battery voltage is too high, the comparator outputs a high-level signal, at which time the drive unit controls the switch unit to turn off, and the battery voltage will not be input to the load through the switch unit; when the battery voltage returns to normal, the comparator outputs a low-level signal, at which time the drive unit controls the switch unit to turn on, and the battery voltage is input to the load for power supply through the switch unit. This achieves overvoltage protection while also realizing power supply self-recovery. Attached Figure Description

[0016] Figure 1This is a circuit diagram of the present invention as shown in the embodiments. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0018] like Figure 1 As shown, the overvoltage protection circuit provided in this embodiment includes a voltage detection unit 1, a reference voltage generation unit 2, a comparison unit 3, a driving unit 4, and a switching unit 5; Voltage detection unit 1 is used to detect the battery voltage and input the detected voltage to the positive input terminal of comparison unit 3; The reference voltage generation unit 2 generates a reference voltage based on the battery voltage and inputs it to the negative input terminal of the comparison unit 3; The drive unit 4 is electrically connected to the output of the comparator unit 3. The switch unit 5 is turned on and off based on the signal output from the output of the comparator unit 3. The input of the switch unit 5 is used to input the battery voltage.

[0019] In practical use, when the battery voltage is too high, the comparison unit 3 outputs a high-level signal. At this time, the drive unit 4 controls the switch unit 5 to turn off, and the battery voltage will not be input to the load through the switch unit 5. When the battery voltage returns to normal, the comparison unit 3 outputs a low-level signal. At this time, the drive unit 4 controls the switch unit 5 to turn on, and the battery voltage is input to the load through the switch unit 5 to supply power. This achieves both overvoltage protection and power supply self-recovery.

[0020] Specifically, in this embodiment, the process by which the driving unit 4 controls the switching unit 5 based on the comparison unit 3 is as follows: When the output of the comparison unit 3 is low, the driving unit 4 drives the switching unit 5 to turn on; when the output of the comparison unit 3 is high, the driving unit 4 drives the switching unit 5 to turn off.

[0021] Specifically, in this embodiment, in Figure 1 In the middle, the voltage detection unit 1 includes resistor R1 and resistor R2. One end of resistor R1 is used to input the battery voltage, and the other end of resistor R1 is electrically connected to the positive input terminal of the comparison unit and grounded through the battery R2.

[0022] Resistors R1 and R2 form a voltage divider circuit. The voltage division ratio of resistors R1 and R2 can be set according to actual needs. For example, by making the resistance values ​​of resistors R1 and R2 the same, the voltage division ratio is set to one-half, so that the detected voltage is one-half of the battery voltage.

[0023] Specifically, in this embodiment, in Figure 1 In the reference voltage generation unit 2, there are resistor R3 and Zener diode V1. One end of resistor R3 is used to input the battery voltage, and the other end of resistor R3 is electrically connected to the negative input terminal of the comparator unit and the cathode of Zener diode V1. The anode of Zener diode V1 is grounded.

[0024] In one implementation, the remaining circuitry can be configured to generate a reference voltage as needed, for example, by generating a voltage drop across the load resistor using a current source.

[0025] Specifically, in this embodiment, in Figure 1 In the comparison unit, there are comparator CMP1 and resistor R4. The negative input terminal of comparator CMP1 is the negative input terminal of the comparison unit, and the positive input terminal of comparator CMP1 is the positive input terminal of the comparison unit. The output terminal of comparator CMP1 is connected to the output terminal of the comparison unit through resistor R4.

[0026] In practical use, when the detection voltage input to the positive input terminal of comparator CMP1 is greater than the reference voltage input to the negative input terminal of comparator CMP1, the output terminal of comparator CMP1 outputs a high-level signal, and vice versa.

[0027] In addition, resistor R4 is a hysteresis state regulating resistor, which prevents the switching unit 5 from being frequently activated when the battery voltage repeatedly changes between the normal operating voltage range and overvoltage, thereby ensuring the stability of the subsequent circuit.

[0028] Specifically, in this embodiment, in Figure 1 In the drive unit 4, there are resistors R5 and R6, transistors Q1 and Q2. The base of transistor Q1 is electrically connected to the output terminal of the comparator unit, the collector of transistor Q1 is electrically connected to the base of transistor Q2, the emitter of transistor Q1 is grounded, the emitter of transistor Q2 is electrically connected to one end of resistor R5 for inputting battery voltage, and the collector of transistor Q2 is electrically connected to the control terminal of the switch unit and the other end of resistor R5, and is grounded through resistor R6.

[0029] In addition, transistor Q1 is an NPN transistor; transistor Q2 is a PNP transistor.

[0030] Specifically, in this embodiment, in Figure 1 In the middle, the switching unit 5 includes a switching transistor Q3. The input terminal of the switching transistor Q3 is the input terminal of the switching unit, the control terminal of the switching transistor Q3 is the control terminal of the switching unit, and the output terminal of the switching transistor Q3 is the output terminal of the switching unit.

[0031] In addition, the switch Q3 is a PMOS transistor. The source of the PMOS transistor is the input terminal of the switch Q3, the gate of the PMOS transistor is the control terminal of the switch Q3, and the drain of the PMOS transistor is the output terminal of the switch Q3. In practical use, when the output of comparator CMP1 outputs a high-level signal, transistors Q1 and Q2 are turned on, thereby pulling up the control terminal voltage of switch Q3 and turning off switch Q3. When the output of comparator CMP1 is low, transistors Q1 and Q2 are turned off. The battery voltage is then divided by resistors R5 and R6 and input to the control terminal of switch Q3, causing switch Q3 to turn on.

[0032] Based on the above description and inspired by this utility model, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An overvoltage protection circuit, characterized by, It includes a voltage detection unit, a reference voltage generation unit, a comparison unit, a drive unit, and a switching unit; The voltage detection unit is used to detect the battery voltage and input the detected voltage to the positive input terminal of the comparison unit; The reference voltage generation unit generates a reference voltage based on the battery voltage, which is input to the negative input terminal of the comparison unit. The driving unit is electrically connected to the output terminal of the comparator unit, and controls the switching unit to open and close based on the signal output from the output terminal of the comparator unit. The input terminal of the switching unit is used to input the battery voltage. The driving unit drives the switching unit to turn on when it outputs a low-level signal at the output terminal of the comparison unit, and drives the switching unit to turn off when it outputs a high-level signal at the output terminal of the comparison unit. The driving unit includes resistors R5 and R6, transistors Q1 and Q2. The base of transistor Q1 is electrically connected to the output terminal of the comparator unit, the collector of transistor Q1 is electrically connected to the base of transistor Q2, the emitter of transistor Q1 is grounded, and the emitter of transistor Q2 is electrically connected to one end of resistor R5 for inputting the battery voltage. The collector of transistor Q2 is electrically connected to the control terminal of the switching unit and the other end of resistor R5, and is grounded through resistor R6. Transistor Q1 is an NPN transistor, and transistor Q2 is a PNP transistor. The switching unit includes a switching transistor Q3. The input terminal of the switching transistor Q3 is the input terminal of the switching unit, the control terminal of the switching transistor Q3 is the control terminal of the switching unit, and the output terminal of the switching transistor Q3 is the output terminal of the switching unit. The switch Q3 is a PMOS transistor. The source of the PMOS transistor is the input terminal of the switch Q3, the gate of the PMOS transistor is the control terminal of the switch Q3, and the drain of the PMOS transistor is the output terminal of the switch Q3.

2. An overvoltage protection circuit according to claim 1, characterized in that The voltage detection unit includes resistors R1 and R2. One end of resistor R1 is used to input the battery voltage, and the other end of resistor R1 is electrically connected to the positive input terminal of the comparison unit and grounded through the battery R2.

3. The overvoltage protection circuit of claim 1, wherein, The reference voltage generating unit includes a resistor R3 and a Zener diode V1. One end of the resistor R3 is used to input the battery voltage, and the other end of the resistor R3 is electrically connected to the negative input terminal of the comparator unit and the cathode of the Zener diode V1. The anode of the Zener diode V1 is grounded.

4. The overvoltage protection circuit of claim 1, wherein The comparison unit includes a comparator CMP1 and a resistor R4. The negative input terminal of the comparator CMP1 is the negative input terminal of the comparison unit, and the positive input terminal of the comparator CMP1 is the positive input terminal of the comparison unit. The comparator CMP1 is connected to the output terminal of the comparator through the resistor R4. The output terminal of the comparator CMP1 is the output terminal of the comparison unit.

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