OVP withdrawing protection circuit

Abstract

The utility model discloses an OVP withdrawing protection circuit comprising an input unit, a detection unit and an output unit, and the input unit at least comprises a DC power supply; the detection unit is electrically connected to the input unit, the detection unit at least comprises a first switch tube, a second switch tube and a detection point, the first switch tube is electrically connected to the detection point, and the first switch tube is configured to be turned on / off according to a comparison result of a voltage value of the detection point and a pin voltage value of the first switch tube; the output unit is electrically connected to the second switch tube. According to the technical scheme, the input voltage is withdrawn after OVP protection, the voltage is prevented from repeatedly oscillating near a protection point to burn out circuit elements such as a protection switch, the OVP is achieved through hardware, the detection time is short, and the service life of the elements is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field, in particular to an OVP withdrawal protection circuit. Background Art

[0002] OVP (Over Voltage Protection) is an overvoltage protection. When the voltage exceeds the preset level, the power supply is turned off or the output is suspended, which protects the subsequent circuits and prevents damage to the subsequent circuits due to excessive input voltage. The principle is that when the input voltage is too large, the internal logic and drive circuit will turn off the MOSFET. At this time, the input and output will be disconnected, and there will be no output voltage, which plays a role in protecting the back end. When the input voltage returns to the normal working voltage, OVP turns on the MOSFET again and the output voltage is normal.

[0003] The existing OVP automatic protection has the following problems: after the automatic protection, the voltage does not retreat, which can easily cause repeated oscillations near the protection point, thereby burning circuit components such as protection switches; OVP is implemented using software, and the detection time is long, which can easily reduce the life of components. Utility Model Content

[0004] The main purpose of the utility model is to provide an OVP withdrawal protection circuit, which aims to withdraw the input voltage after OVP protection to prevent the voltage from repeatedly oscillating near the protection point and burning circuit components such as the protection switch. In addition, OVP is implemented using hardware, with a short detection time, which increases the life of components.

[0005] In order to achieve the above object, the utility model proposes an OVP withdrawal protection circuit, comprising:

[0006] An input unit, the input unit comprising at least a DC power supply;

[0007] A detection unit, the detection unit is electrically connected to the input unit, the detection unit at least comprises a first switch tube, a second switch tube and a detection point, the first switch tube is electrically connected to the detection point, and the first switch tube is configured to be turned on / off according to a comparison result between a voltage value of the detection point and a voltage value of a pin of the first switch tube;

[0008] An output unit, the output unit being electrically connected to the second switch tube;

[0009] Among them, when the voltage at the detection point is higher than the pin voltage of the first switch tube, the first switch tube and the second switch tube are turned off, and the output unit is powered off. After reducing the voltage value of the DC power supply, the voltage at the detection point is lower than the pin voltage of the first switch tube, and the first switch tube and the second switch tube are turned on to power on the output unit.

[0010] In one embodiment of the present invention, the detection unit further includes a first resistor, a second resistor and a third resistor, the first resistor is connected in series with the second resistor, the third resistor is connected in parallel with the second resistor, and the detection point is located between the first resistor and the second resistor.

[0011] In an embodiment of the present invention, the detection unit further includes a first MOS tube and a second MOS tube connected in parallel with each other, the first MOS tube is connected in parallel to the first switch tube, and the second MOS tube is connected in series to the third resistor.

[0012] In an embodiment of the present invention, the resistance of the third resistor is ten times the resistance of the second resistor.

[0013] In an embodiment of the present invention, the input unit further includes an MCU, and the MCU is electrically connected to the DC power supply and the detection unit.

[0014] The technical solution of the utility model compares the pin voltage of the first switch tube with the voltage of the detection point. If the DC power supply is higher than the set voltage protection value, the voltage at the detection point is higher than the pin voltage of the first switch tube. At this time, the pin of the first switch tube changes from the original high-impedance state to a low level, thereby turning off the second switch tube and disconnecting the output unit to protect the subsequent circuit from damage. The DC power supply needs to withdraw a part of the voltage to make the voltage at the detection point lower than the voltage of the pin of the first switch tube, so that the pin of the first switch tube can be changed to a high-impedance state and the second switch tube can be turned on, thereby avoiding repeated oscillations of the voltage near the protection point, thereby burning the first switch tube and other circuit components. In addition, OVP is implemented using hardware, with a short detection time and a prolonged life of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 The utility model is a circuit diagram of the OVP withdrawal protection circuit.

[0017] Description of Figure Numbers:

[0018] 1. Input unit; 2. Detection unit; 3. Output unit; Vin, DC power supply; Q1, first switch tube; Q2, second switch tube; Q3, first MOS tube; Q4, second MOS tube; R1, first resistor; R2, second resistor; R3, third resistor; U1, MCU; P, detection point.

[0019] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Reference Figure 1 The utility model proposes an OVP withdrawal protection circuit, including an input unit 1, a detection unit 2 and an output unit 3, wherein the input unit 1 at least includes a DC power supply Vin; the detection unit 2 is electrically connected to the input unit 1, and the detection unit 2 at least includes a first switch tube Q1, a second switch tube Q2 and a detection point P, the first switch tube Q1 is electrically connected to the detection point P, and the first switch tube Q1 is configured to be turned on / off according to a comparison result between a voltage value of the detection point P and a pin voltage value of the first switch tube Q1; the output unit 3 is electrically connected to the second switch tube Q2; wherein, when the voltage of the detection point P is higher than the pin voltage of the first switch tube Q1, the first switch tube Q1 and the second switch tube Q2 are turned off, the output unit 3 is powered off, and after reducing the voltage value of the DC power supply Vin, the voltage of the detection point P is lower than the pin voltage of the first switch tube Q1, the first switch tube Q1 and the second switch tube Q2 are turned on, so that the output unit 3 is powered on.

[0022] It can be understood that when the DC power supply Vin is connected, the first switch tube Q1 is normally turned on. The first switch tube Q1 has three pins, namely pin 1, pin 2 and pin 3. Pin 1 is connected to the detection point P, and the pin voltage of pin 1 is compared with the voltage of the detection point P. If the DC power supply Vin is higher than the set voltage protection value, the voltage of the detection point P is higher than the voltage of pin 1 of the first switch tube Q1. At this time, pins 2 and 3 of the first switch tube Q1 change from the original high impedance state to a low level, thereby turning off the second switch tube Q2 and disconnecting the output unit 3 to protect the subsequent circuit from damage. The DC power supply Vin needs to withdraw a part of the voltage to make the voltage of the detection point P lower than the voltage of the pin 1 of the first switch tube Q1, so that pins 2 and 3 of the first switch tube Q1 can become high impedance and the second switch tube Q2 can be turned on, thereby ensuring that the detection point P maintains the originally set safety voltage.

[0023] Reference Figure 1In one embodiment of the present application, the detection unit 2 also includes a first resistor R1, a second resistor R2 and a third resistor R3. The first resistor R1 is connected in series with the second resistor R2, the third resistor R3 is connected in parallel with the second resistor R2, and the detection point P is between the first resistor R1 and the second resistor R2.

[0024] It can be understood that the voltage of pin 1 of the first switch tube Q1 and the voltage of the second resistor R2 in parallel with the third resistor R3 are compared with the voltage divided by the first resistor R1. If the voltage of the detection point P is higher than the voltage of pin 1 of the first switch tube Q1, the pins 2 and 3 of the first switch tube Q1 are changed from the original high impedance state to a low level, thereby turning off the second switch tube Q2 and disconnecting the output unit 3 to protect the subsequent circuit from damage. When the input voltage drops, since the second switch tube Q2 is in a closed state, the original parallel impedance of the second resistor R2 and the third resistor R3 is changed to the single impedance of the second resistor R2, resulting in a higher voltage at the detection point P, so that the DC power supply Vin needs to withdraw a part of the voltage to make the potential of the detection point P lower than the potential of the first switch tube Q11 pin, so that the pins 2 and 3 of the first switch tube Q1 can be changed into a high impedance state, so that the turn-on impedance of the second switch tube Q2 is restored to the parallel impedance of the second resistor R2 and the third resistor R3, thereby ensuring that the detection point P maintains the original set safety voltage.

[0025] Reference Figure 1 In one embodiment of the present application, the detection unit 2 further includes a first MOS tube Q3 and a second MOS tube Q4 connected in parallel with each other, the first MOS tube Q3 is connected in parallel to the first switch tube Q1, and the second MOS tube Q4 is connected in series to the third resistor R3.

[0026] It can be understood that the provision of the first MOS tube Q3 and the second MOS tube Q4 can further control the on-off of the detection unit 2. If the voltage at the detection point P is higher than the voltage at the pin 1 of the first switch tube Q1, the pins 2 and 3 of the first switch tube Q1 are changed from the original high impedance state to a low level, and the first MOS tube Q3 and the second MOS tube Q4 are turned off, thereby turning off the second switch tube Q2 of the detection unit 2, disconnecting the output unit 3, and protecting the subsequent circuit from damage; when a part of the voltage is withdrawn from the DC power supply Vin, the potential of the detection point P is lower than the potential of the pin 1 of the first switch tube Q1, and the pins 2 and 3 of the first switch tube Q1 can be changed to a high impedance state, so that the first MOS tube Q3 and the second MOS tube Q4 are turned on, and the second switch tube Q2 is turned on.

[0027] Reference Figure 1 In one embodiment of the present application, the resistance of the third resistor R3 is ten times the resistance of the second resistor R2.

[0028] It can be understood that by adjusting the resistance value of the resistor, the withdrawal voltage value of the DC power supply Vin when the first switch tube Q1 is turned off can be changed. In this example, the resistance value of the first resistor R1 is 100k ohms, the resistance value of the second resistor R2 is 4.7k ohms, and the resistance value of the third resistor R3 is 47k ohms. The input range of the DC power supply Vin is 12 to 60 volts. When the first switch tube Q1 is turned on, the voltage at the detection point P is the voltage obtained by dividing the second resistor R2 in parallel with the third resistor R3 and the first resistor R1, and the value is small. When the voltage of the DC power supply Vin is too large, the first switch tube Q1 is turned off, and the voltage at the detection point P becomes the voltage obtained by dividing the single impedance of the second resistor R2 and the first resistor R1, and the value is high. The DC power supply Vin needs to be withdrawn by about 5 volts to make the potential of the detection point P lower than the potential of the first switch tube Q11 pin, so that the voltage of the DC power supply Vin is within a safe range. After the voltage is withdrawn, the voltage is prevented from repeatedly oscillating near the set voltage protection value, thereby burning circuit components.

[0029] Reference Figure 1 In one embodiment of the present application, the input unit 1 further includes an MCUU1 , which is electrically connected to a DC power supply Vin and a detection unit 2 .

[0030] It can be understood that MCUU1 enables or activates the pin channel in the first switch tube Q1 through CH-EN (channel enable). Compared with the circuit that uses software to implement OVP, the detection time is shorter and it is not easy to cause damage to components.

[0031] The technical solution of the utility model compares the pin voltage of the first switch tube Q1 with the voltage of the detection point P. If the DC power supply Vin is higher than the set voltage protection value, the voltage of the detection point P is higher than the pin voltage of the first switch tube Q1. At this time, the pin of the first switch tube Q1 changes from the original high-impedance state to a low level, thereby turning off the second switch tube Q2 and disconnecting the output unit 3 to protect the subsequent circuit from damage. The DC power supply Vin needs to withdraw a part of the voltage to make the voltage of the detection point P lower than the voltage of the pin of the first switch tube Q1, so that the pin of the first switch tube Q1 can be changed to a high-impedance state and the second switch tube Q2 can be turned on, thereby avoiding repeated oscillations of the voltage near the protection point, thereby burning circuit components such as the first switch tube Q1. In addition, OVP is implemented using hardware, with a short detection time, which increases the life of components.

[0032] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An OVP retracement protection circuit, characterized in that: include: An input unit, the input unit comprising at least a DC power supply; A detection unit, the detection unit is electrically connected to the input unit, the detection unit at least comprises a first switch tube, a second switch tube and a detection point, the first switch tube is electrically connected to the detection point, and the first switch tube is configured to be turned on / off according to a comparison result between a voltage value of the detection point and a voltage value of a pin of the first switch tube; An output unit, the output unit being electrically connected to the second switch tube; Among them, when the voltage at the detection point is higher than the pin voltage of the first switch tube, the first switch tube and the second switch tube are turned off, and the output unit is powered off. After reducing the voltage value of the DC power supply, the voltage at the detection point is lower than the pin voltage of the first switch tube, and the first switch tube and the second switch tube are turned on to power on the output unit.

2. The OVP retracement protection circuit according to claim 1, characterized in that: The detection unit further includes a first resistor, a second resistor and a third resistor, the first resistor is connected in series with the second resistor, the third resistor is connected in parallel with the second resistor, and the detection point is located between the first resistor and the second resistor.

3. The OVP retracement protection circuit according to claim 2, characterized in that: The detection unit further includes a first MOS tube and a second MOS tube connected in parallel with each other, the first MOS tube is connected in parallel to the first switch tube, and the second MOS tube is connected in series to the third resistor.

4. The OVP retracement protection circuit according to claim 2, characterized in that: The resistance of the third resistor is ten times the resistance of the second resistor.

5. The OVP pullback protection circuit according to any one of claims 1 to 4, characterized in that: The input unit further includes an MCU, and the MCU is electrically connected to the DC power supply and the detection unit.

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