Adjustable overvoltage protection circuit

Abstract

The invention belongs to the technical field of overvoltage protection circuits, and particularly relates to an adjustable overvoltage protection circuit, which comprises a voltage input port VIN and a voltage output port VOUT, the voltage input port VIN is connected with a voltage feedback regulation circuit, the voltage feedback regulation circuit is connected with a control protection circuit, and the control protection circuit is connected with the voltage output port VOUT. The control protection circuit is connected with a voltage output port VOUT, the voltage feedback regulation circuit comprises resistors R1, R2, R4, R5 and R6, a PNP triode Q1 and a voltage reference chip U1, the resistor R4 is a slide rheostat with the resistance value of 1-100 K omega, the control protection circuit comprises a differential operational amplifier U1B, a comparator U2B and a P-type MOS tube M1, and the resistor R11 is a slide rheostat with the resistance value of 1-100 K omega. The protection function of over-voltage automatic cut-off is achieved; the function of an imported chip is achieved through the combination of domestic devices; the circuit is simplified; and the circuit maintainability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of overvoltage protection circuits, and specifically provides an adjustable overvoltage protection circuit. Background Art

[0002] An overvoltage protection circuit is a circuit used to prevent a circuit from being damaged due to an excessively high input voltage. Principle: It monitors the input voltage of the circuit in real time. When the voltage exceeds a pre-set threshold, it quickly takes measures to cut off the power supply or adjust the circuit state to avoid damage to sensitive components in the circuit caused by the excessive voltage.

[0003] The existing overvoltage protection circuits have the following defects: The current structure combination of overvoltage protection circuits is relatively complex. When performing overvoltage protection, the cut-off is not timely, and the protection effect on the circuit is not timely. Summary of the Invention

[0004] The purpose of the present invention is to provide an adjustable overvoltage protection circuit to solve the problems in the above background art that the current structure combination of overvoltage protection circuits is relatively complex, the cut-off is not timely when performing overvoltage protection, and the protection effect on the circuit is not timely.

[0005] To achieve the above purpose, the present invention provides the following technical solution: An adjustable overvoltage protection circuit includes:

[0006] A voltage input port VIN and a voltage output port VOUT;

[0007] Among them, the voltage input port VIN is connected to a voltage feedback adjustment circuit, the voltage feedback adjustment circuit is connected to a control protection circuit, and the control protection circuit is connected to the voltage output port VOUT.

[0008] Preferably, the voltage feedback adjustment circuit includes resistors R1, R2, R4, R5, R6, a PNP transistor Q1, and a voltage reference chip U1. The voltage input port VIN is connected to one end of resistor R4, one end of resistor R1, and the emitter of PNP transistor Q1. The other end of resistor R4 is connected to one end of resistor R6 and the voltage reference chip U1. The other end of resistor R6 is connected to the voltage reference chip U1 and one end of resistor R5. The voltage reference chip U1 is connected to the other end of resistor R1 and one end of resistor R2. The other end of resistor R2 is connected to the base of PNP transistor Q1. The other end of resistor R5 is connected to the collector of PNP transistor Q1.

[0009] Preferably, the resistor R4 is a sliding rheostat with a resistance value of 1 KΩ - 100 KΩ.

[0010] Preferably, the control and protection circuit includes a differential operational amplifier U1B, a comparator U2B, and a P-type MOS transistor M1. The positive input pin of the differential operational amplifier U1B is connected to one end of a resistor R9. The other end of the resistor R9 is connected to one end of a resistor R7 and the drain of the P-type MOS transistor M1. The other end of the resistor R7 is connected to a voltage output port VOUT and one end of a resistor R10. The other end of the resistor R10 is connected to the negative input pin of the differential operational amplifier U1B. The output end of the differential operational amplifier U1B is connected to the positive input pin of the comparator U2B. The negative input pin of the comparator U2B is connected to a resistor R11 and a resistor R12. The other end of the resistor R12 is grounded. The output end of the comparator U2B is connected to the base of a triode Q3. The emitter of the triode Q3 is grounded. The collector of the triode Q3 is connected to one end of a resistor R8. The other end of the resistor R8 is connected to the base of a triode Q2. The collector of the triode Q2 is connected to one end of a resistor R3, the collector of a PNP triode Q1, and the source of the P-type MOS transistor M1. The other end of the resistor R3 is connected to the emitter of the PNP triode Q1 and the emitter of the triode Q2. The emitter of the triode Q2 is connected to the gate of the P-type MOS transistor M1. The drain of the P-type MOS transistor M1 is connected to one end of the resistor R7.

[0011] Preferably, the resistor R11 is a sliding rheostat with a resistance value of 1KΩ - 100KΩ.

[0012] Preferably, the voltage input port VIN obtains a voltage UA through voltage division by resistors R4 and R6. The voltage UA detection point is at the connection between the resistors R4 and R6. The resistance value of the resistor R3 is 30KΩ, and the resistance value of the resistor R5 is 30KΩ.

[0013] The resistors R3 and R5 provide a VGS voltage for the P-type MOS transistor M1. When the VGS voltage is greater than 1.5V, the P-type MOS transistor M1 conducts.

[0014] When VGS is less than 1.5V, the P-type MOS transistor M1 is turned off.

[0015] The resistance value of the resistor R1 is 2KΩ, and the resistance value of the resistor R2 is 10KΩ. When the voltage reference chip U1 conducts in the reverse direction, the PNP triode Q1 conducts. When the voltage reference chip U1 does not conduct, the PNP triode Q1 is cut off.

[0016] When the voltage of the voltage UA is less than or equal to 2.5V, the voltage reference chip U1 does not work, and the P-type MOS transistor M1 conducts.

[0017] When the voltage of the voltage UA is greater than 2.5V, the voltage reference chip U1 works, the triode Q2 conducts, resulting in VGS being less than 1.5V, and then the P-type MOS transistor M1 is turned off.

[0018] The resistor R4 is an adjustable resistor, and the threshold of overvoltage protection is adjusted by adjusting the resistance value of the resistor R4;

[0019] Formula: When VIN*R6 / (R4 + R6) is greater than 2.5V, the circuit will start the overvoltage protection action, where VIN is the input voltage of the voltage input port VIN, and R4 and R6 respectively represent the resistance values of the resistors R4 and R6.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] A protection circuit with automatic overvoltage cut-off is composed of discrete devices such as resistors, P-type MOS transistors, PNP transistors, and sliding rheostats. It has the protection function of automatic overvoltage cut-off; the function of imported chips is achieved through the combination of domestic devices; the circuit is simplified; and the maintainability of the circuit is increased. Description of the Drawings

[0022] Figure 1 It is the overvoltage protection circuit diagram of the present invention. Detailed Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention 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, and therefore should not be construed as a limitation of the present invention.

[0025] Embodiment 1:

[0026] Please refer to Figure 1 , the present invention provides a technical solution: an adjustable overvoltage protection circuit, characterized in that it includes: a voltage input port VIN and a voltage output port VOUT;

[0027] Among them, the voltage input port VIN is connected to the voltage feedback adjustment circuit, the voltage feedback adjustment circuit is connected to the control protection circuit, and the control protection circuit is connected to the voltage output port VOUT.

[0028] The voltage feedback regulation circuit includes resistors R1, R2, R4, R5, R6, a PNP transistor Q1, and a voltage reference chip U1. The voltage input port VIN is connected to one end of resistor R4, one end of resistor R1, and the emitter of the PNP transistor Q1. The other end of resistor R4 is connected to one end of resistor R6 and the voltage reference chip U1. The other end of resistor R6 is connected to the voltage reference chip U1 and one end of resistor R5. The voltage reference chip U1 is connected to the other end of resistor R1 and one end of resistor R2. The other end of resistor R2 is connected to the base of the PNP transistor Q1. The other end of resistor R5 is connected to the collector of the PNP transistor Q1. Resistor R4 is a slide rheostat with a resistance value of 1KΩ - 100KΩ.

[0029] The control and protection circuit includes a differential operational amplifier U1B, a comparator U2B, and a P-type MOS transistor M1. The positive input pin of the differential operational amplifier U1B is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R7 and the drain of the P-type MOS transistor M1. The other end of resistor R7 is connected to the voltage output port VOUT and one end of resistor R10. The other end of resistor R10 is connected to the negative input pin of the differential operational amplifier U1B. The output end of the differential operational amplifier U1B is connected to the positive input pin of the comparator U2B. The negative input pin of the comparator U2B is connected to resistors R11 and R12. The other end of resistor R12 is grounded. The output end of the comparator U2B is connected to the base of the transistor Q3. The emitter of the transistor Q3 is grounded. The collector of the transistor Q3 is connected to one end of resistor R8. The other end of resistor R8 is connected to the base of the transistor Q2. The collector of the transistor Q2 is connected to one end of resistor R3, the collector of the PNP transistor Q1, and the source of the P-type MOS transistor M1. The other end of resistor R3 is connected to the emitter of the PNP transistor Q1 and the emitter of the transistor Q2. The emitter of the transistor Q2 is connected to the gate of the P-type MOS transistor M1. The drain of the P-type MOS transistor M1 is connected to one end of resistor R7. Resistor R11 is a slide rheostat with a resistance value of 1KΩ - 100KΩ.

[0030] Analysis of the above content: The voltage input port VIN obtains voltage UA through voltage division by resistors R4 and R6. The voltage UA detection point is at the connection between resistors R4 and R6. The resistance value of resistor R3 is 30KΩ, and the resistance value of resistor R5 is 30KΩ.

[0031] Voltage division by resistors R3 and R5 provides the VGS voltage for the P-type MOS transistor M1. When the VGS voltage is greater than 1.5V, the P-type MOS transistor M1 conducts.

[0032] When VGS is less than 1.5V, the P-type MOS transistor M1 is turned off.

[0033] The resistance value of resistor R1 is 2KΩ, and the resistance value of resistor R2 is 10KΩ. When the voltage reference chip U1 conducts in the reverse direction, the PNP transistor Q1 conducts. When the voltage reference chip U1 does not conduct, the PNP transistor Q1 is cut off and disconnected.

[0034] When the voltage of voltage UA is less than or equal to 2.5V, the voltage reference chip U1 does not work, and the P-type MOS transistor M1 conducts.

[0035] When the voltage of voltage UA is greater than 2.5V, the voltage reference chip U1 works, the transistor Q2 conducts, resulting in VGS being less than 1.5V, and then the P-type MOS transistor M1 is disconnected.

[0036] Resistor R4 is an adjustable resistor, and the overvoltage protection threshold is adjusted by adjusting the resistance value of resistor R4.

[0037] Formula: When VIN*R6 / (R4 + R6) is greater than 2.5V, the circuit will start the overvoltage protection action, where VIN is the input voltage of the voltage input port VIN, and R4 and R6 represent the resistance values of resistor R4 and resistor R6 respectively.

[0038] This solution is based on the existing technology, with new functions: adjustable overcurrent protection function

[0039] New circuit:

[0040] Differential op-amp: The voltage across resistor R7 can be output to the non-inverting terminal of comparator U2B through the differential operation of differential op-amp U1B with a gain of 1:1.

[0041] Comparator U2B: 5V is divided by resistor R11 and resistor R12 and applied to the inverting terminal of comparator U2B. When the voltage at the non-inverting terminal is greater than the inverting terminal, comparator U2B outputs high.

[0042] New transistors Q2, transistor Q3, resistor R8: When comparator U2B outputs high, transistor Q3 conducts. If transistor Q3 conducts, transistor Q2 conducts. If transistor Q2 conducts, VGS of P-type MOS transistor M1 = 0V. Therefore, at this time, P-type MOS transistor M1 is disconnected.

[0043] Overcurrent protection calculation: (Important technical key)

[0044] When the voltage of UD (between the output terminal of differential op-amp U1B in the figure and the positive input pin of comparator U2B) is less than or equal to UE (the connection point between the negative input pin of comparator U2B and resistor R12), comparator U2B outputs low, transistors Q2 and transistor Q3 are cut off, and the P-type MOS transistor conducts.

[0045] When the voltage at UD (between the output terminal of the differential operational amplifier U1B and the positive input pin of the comparator U2B in the figure) is greater than UE, the comparator U2B outputs high, and the triodes Q2 and Q3 conduct, resulting in VGS being less than 1.5V, and then the P-type MOS transistor M1 is turned off.

[0046] Since the resistor R11 is an adjustable resistor, the threshold value of the overcurrent protection can be adjusted by adjusting the resistance value of the resistor R11.

[0047] Formula: When I*R7 is greater than R12 / (R2 + R11)*5V, the circuit will start the overcurrent protection operation, where R7, R12, R2, and R11 respectively represent the resistance values of the resistors R7, R12, R2, and R11.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present invention, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0049] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An adjustable overvoltage protection circuit, characterized in that: include: Voltage input port VIN, voltage output port VOUT; The voltage input port VIN is connected to a voltage feedback regulation circuit, the voltage feedback regulation circuit is connected to a control protection circuit, and the control protection circuit is connected to a voltage output port VOUT.

2. The adjustable overvoltage protection circuit according to claim 1, characterized in that: The voltage feedback regulation circuit includes resistors R1, R2, R4, R5, R6, a PNP transistor Q1, and a voltage reference chip U1. The voltage input port VIN is connected to one end of the resistor R4, one end of the resistor R1, and the emitter of the PNP transistor Q1. The other end of the resistor R4 is connected to one end of the resistor R6 and the voltage reference chip U1. The other end of the resistor R6 is connected to the voltage reference chip U1 and one end of the resistor R5. The voltage reference chip U1 is connected to the other end of the resistor R1 and one end of the resistor R2. The other end of the resistor R2 is connected to the base of the PNP transistor Q1. The other end of the resistor R5 is connected to the collector of the PNP transistor Q1.

3. The adjustable overvoltage protection circuit according to claim 2, characterized in that: The resistor R4 is a sliding resistor with a resistance value of 1KΩ-100KΩ.

4. The adjustable overvoltage protection circuit according to claim 3, characterized in that: The control protection circuit includes a differential operational amplifier U1B, a comparator U2B, and a P-type MOS tube M1. The positive input pin of the differential operational amplifier U1B is connected to one end of a resistor R9, the other end of the resistor R9 is connected to one end of a resistor R7 and the drain of the P-type MOS tube M1, the other end of the resistor R7 is connected to a voltage output port VOUT and one end of a resistor R10, the other end of the resistor R10 is connected to a negative input pin of the differential operational amplifier U1B, the output end of the differential operational amplifier U1B is connected to the positive input pin of the comparator U2B, the negative input pin of the comparator U2B is connected to resistors R11 and R12, and the resistor R1 2 is grounded, the output end of the comparator U2B is connected to the base of the transistor Q3, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to one end of the resistor R3, the collector of the PNP transistor Q1, and the source of the P-type MOS tube M1, the other end of the resistor R3 is connected to the emitter of the PNP transistor Q1 and the emitter of the transistor Q2, the emitter of the transistor Q2 is connected to the gate of the P-type MOS tube M1, and the drain of the P-type MOS tube M1 is connected to one end of the resistor R7.

5. The adjustable overvoltage protection circuit according to claim 4, characterized in that: The resistor R11 is a sliding resistor with a resistance value of 1KΩ-100KΩ.

6. The adjustable overvoltage protection circuit according to claim 4, characterized in that: The voltage input port VIN obtains the voltage UA through the voltage division of the resistors R4 and R6. The voltage UA detection point is at the connection between the resistors R4 and R6. The resistance value of the resistor R3 is 30KΩ, and the resistance value of the resistor R5 is 30KΩ. The resistors R3 and R5 divide the voltage to provide the VGS voltage for the P-type MOS tube M1. When the VGS voltage is greater than 1.5V, the P-type MOS tube M1 is turned on. When VGS is less than 1.5V, the P-type MOS tube M1 is disconnected; The resistance value of the resistor R1 is 2KΩ, and the resistance value of the resistor R2 is 10KΩ. When the voltage reference chip U1 is reversely conducting, the PNP transistor Q1 is conducting. When the voltage reference chip U1 is not conducting, the PNP transistor Q1 is cut off and disconnected. When the voltage UA is less than or equal to 2.5V, the voltage reference chip U1 does not work, and the P-type MOS tube M1 is turned on; When the voltage UA is greater than 2.5V, the voltage reference chip U1 works, the transistor Q2 is turned on, causing VGS to be less than 1.5V, and then the P-type MOS tube M1 is disconnected; Resistor R4 is an adjustable resistor, and the threshold of overvoltage protection is adjusted by adjusting the resistance value of resistor R4; Formula: When VIN*R6 / (R4+R6) is greater than 2.5V, the circuit will start the overvoltage protection action, where VIN is the input voltage of the voltage input port VIN, and R4 and R6 represent the resistance values ​​of resistors R4 and R6 respectively.

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