Overvoltage protection circuit and electric equipment power supply system thereof
By introducing a voltage divider unit and a reference voltage control unit into the overvoltage protection circuit, combined with the rapid switching of PMOS transistors and triodes, the problem of misjudgment or missed judgment in existing circuits is solved, and higher accuracy and efficiency overvoltage protection is achieved.
Patent Information
- Application Number
- CN202520299654.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2035-02-21
AI Technical Summary
Existing overvoltage protection circuits use simple voltage comparators, which can lead to false alarms or missed alarms, resulting in low protection accuracy.
Design an overvoltage protection circuit that divides the device output voltage through a first voltage divider unit and transmits the divided voltage to a reference voltage control unit. When the obtained divided voltage differs from its own reference voltage, the reference voltage control unit can accurately control the conduction/cutoff of the first switching unit. Combined with the rapid switching of PMOS transistors and transistors, the circuit can quickly respond to overvoltage events.
It improves the accuracy and efficiency of overvoltage protection, ensures that electrical equipment is protected from overvoltage damage, simplifies the circuit structure, and reduces costs.
Smart Images
Figure CN223884944U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of circuit protection, in particular to an overvoltage protection circuit and an electric equipment power supply system thereof. BACKGROUND
[0002] The overvoltage protection circuit is a circuit design for protecting electronic devices and circuits from overvoltage damage, which has been widely used in power supply protection, communication equipment, household appliances, battery management systems and other application occasions. Its main function is to protect, shunt or limit the voltage through specific components to ensure that the circuit, device and its components are not affected by overvoltage when the voltage in the circuit exceeds the safe working range. Generally, the overvoltage protection circuit is installed at the power input end or important load end, which can quickly respond to voltage changes, thereby achieving the effect of preventing the device from being damaged.
[0003] At present, there are some overvoltage protection circuits on the market, but these circuits often have the problem of low protection accuracy. For example, some overvoltage protection circuits use a simple voltage comparator to detect overvoltage conditions, but due to the limited accuracy of the voltage comparator itself, misjudgment or omission may occur. Therefore, a more accurate and relatively simple overvoltage protection circuit is needed to meet the needs of practical applications. CONTENT OF THE INVENTION
[0004] The purpose of the embodiments of the present application is to provide an overvoltage protection circuit and an electric equipment power supply system thereof, to solve the problem of low overvoltage protection accuracy caused by misjudgment or omission of overvoltage conditions in the overvoltage protection circuit on the market using a simple voltage comparator.
[0005] In a first aspect, the utility model provides an overvoltage protection circuit, comprising: a reference voltage control unit, a first switching unit and a first voltage dividing unit;The input end of the first switching unit is used for being electrically connected with the device voltage input end, the output end of the first switching unit is used for being electrically connected with the device voltage output end, the control end of the first switching unit is electrically connected with the output end of the reference voltage control unit, and the reference end of the reference voltage control unit is electrically connected with the device voltage output end through the first voltage dividing unit;Wherein, the reference voltage control unit is configured to control the first switching unit to be cut off when the received voltage dividing voltage is greater than or equal to the reference voltage of itself;In the case where the received voltage dividing voltage is less than the reference voltage of itself, the first switching unit is controlled to be turned on;Wherein, the voltage dividing voltage is obtained by the first voltage dividing unit dividing the device output voltage of the device voltage output end.
[0006] The overvoltage protection circuit has the advantages that the first voltage dividing unit divides the equipment output voltage and transmits the divided voltage to the reference voltage control unit, the reference voltage control unit accurately controls the on / off of the first switch unit when the obtained divided voltage is different from the reference voltage of the reference voltage control unit, and the accuracy of overvoltage protection is improved based on the divided voltage obtained by the reference voltage control unit and the reference voltage of the reference voltage control unit.
[0007] In an optional implementation of the first aspect, the first voltage dividing unit comprises a first voltage dividing resistor and a second voltage dividing resistor; a first end of the first voltage dividing resistor is electrically connected to the equipment voltage output end, a second end of the first voltage dividing resistor is electrically connected to a first end of the second voltage dividing resistor and a reference end of the reference voltage control unit respectively, and a second end of the second voltage dividing resistor is grounded.
[0008] In the above implementation, the first voltage dividing unit is formed by the simple structure of two voltage dividing resistors, so as to provide a suitable voltage for the reference voltage control unit, thereby simplifying the circuit structure and reducing the circuit cost.
[0009] In an optional implementation of the first aspect, the reference voltage control unit comprises a reference voltage chip, a second switch unit, a second voltage dividing unit and a third voltage dividing unit; the second voltage dividing unit and the third voltage dividing unit are connected in parallel, input ends of the second voltage dividing unit and the third voltage dividing unit are electrically connected to the equipment voltage input end; an output end of the second voltage dividing unit is electrically connected to a control end of the first switch unit, and a grounding end of the second voltage dividing unit is electrically connected to an input end of the second switch unit; a first output end of the third voltage dividing unit is electrically connected to a cathode of the reference voltage chip, and a second output end of the third voltage dividing unit is electrically connected to a control end of the second switch unit; a grounding end of the third voltage dividing unit, an anode of the reference voltage chip and an output end of the second switch unit are grounded, and a reference end of the reference voltage chip is electrically connected to the equipment voltage output end through the first voltage dividing unit.
[0010] In an optional implementation of the first aspect, the second voltage dividing unit comprises a third voltage dividing resistor and a fourth voltage dividing resistor; a first end of the third voltage dividing resistor is electrically connected to the equipment voltage input end, a second end of the third voltage dividing resistor is electrically connected to the control end of the first switch unit and a first end of the fourth voltage dividing resistor respectively, and a second end of the fourth voltage dividing resistor is electrically connected to the input end of the second switch unit.
[0011] In the above implementation, the third voltage dividing resistor designed in the present application not only can divide the input voltage, but also can play a role in preventing ESD static electricity, avoiding being in a high resistance state, and the third voltage dividing resistor also acts as a discharge resistor, which can prevent the first switch unit from malfunctioning, thereby avoiding damage to the first switch unit.
[0012] In an optional implementation of the first aspect, the third voltage dividing unit comprises a fifth voltage dividing resistor, a sixth voltage dividing resistor and a seventh voltage dividing resistor, a first end of the fifth voltage dividing resistor is electrically connected with the device voltage input end, a second end of the fifth voltage dividing resistor is electrically connected with a first end of the sixth voltage dividing resistor and a cathode of the reference voltage chip respectively, a second end of the sixth voltage dividing resistor is electrically connected with a first end of the seventh voltage dividing resistor and a control end of the second switch unit respectively, and a second end of the seventh voltage dividing resistor is grounded.
[0013] In an optional implementation of the first aspect, the first switch unit comprises a PMOS tube, and the second switch unit is a triode; a gate of the PMOS tube is electrically connected with the second end of the third voltage dividing resistor and a collector of the triode respectively, a source of the PMOS tube is electrically connected with the device voltage input end, and a drain of the PMOS tube is electrically connected with the device voltage output end; an emitter of the triode is grounded, and a base of the triode is electrically connected with the second end of the sixth voltage dividing resistor.
[0014] In the above implementation, the first switch unit is designed by using a PMOS tube, and the control of the first switch unit is realized by using a triode in the reference voltage control unit, so that the circuit can quickly respond to an overvoltage event through the rapid switching of the PMOS tube and the triode, and the efficiency of overvoltage protection is improved.
[0015] In an optional implementation of the first aspect, the overvoltage protection circuit further comprises a protection diode; a positive electrode of the protection diode is electrically connected with the gate of the PMOS tube, and a negative electrode of the protection diode is electrically connected with the device voltage input end.
[0016] In the above implementation, the protection diode D1 designed in the present solution can protect the gate and the source of the PMOS tube Q1. Since the MOSFET is an insulated gate field effect tube, the gate has no direct current path, the input impedance is high, and the static charge is easily accumulated, so that a higher voltage is generated to break down the insulation layer between the gate and the source. The protection diode D1 can embed the static electricity below the stable voltage value, and effectively protect the insulation layer of the gate and the source.
[0017] In an optional implementation of the first aspect, the overvoltage protection circuit further comprises a first protection capacitor and a second protection capacitor; the first protection capacitor is connected in parallel with the sixth voltage dividing resistor, and the second protection capacitor is connected in parallel with the first voltage dividing resistor.
[0018] In the above implementation, the first protection capacitor is connected in parallel with the sixth voltage dividing resistor, and the second protection capacitor is connected in parallel with the first voltage dividing resistor, so that the stability and reliability of the overvoltage protection circuit are improved.
[0019] In an optional implementation of the first aspect, the overvoltage protection circuit further comprises a filtering unit; the filtering unit is arranged between the first switch unit and the device voltage output end.
[0020] The above embodiment, the present application through the filter unit to the first switch unit to the device voltage output terminal between the suppression of transient current and noise, thereby improving the anti-interference ability of the designed overvoltage protection circuit.
[0021] In a second aspect, the utility model provides a kind of power supply system of electric equipment, which includes the overvoltage protection circuit of any optional embodiment in the first aspect.
[0022] The above designed power supply system of electric equipment, since it contains the overvoltage protection circuit of the first aspect, therefore, the designed power supply system of electric equipment is passed to the reference voltage control unit by the first voltage divider unit to the device output voltage is divided, and the reference voltage control unit is different in size in the obtained voltage division and self reference voltage, to realize the accurate control of the conduction / cutoff of the first switch unit, to improve the precision of overvoltage protection based on the voltage division obtained by the reference voltage control unit and self reference voltage. BRIEF DESCRIPTION OF DRAWINGS
[0023] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.
[0024] Figure 1 The first structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0025] Figure 2 The second structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0026] Figure 3 The third structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0027] Figure 4 The fourth structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0028] Figure 5 The fifth structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0029] Figure 6 The sixth structure diagram of overvoltage protection circuit provided for the embodiments of the present application;
[0030] Figure 7 The seventh structure diagram of overvoltage protection circuit provided for the embodiments of the present application.
[0031] Icon: 10-reference voltage control unit; 110-reference voltage chip; 120-second switch unit; 130-second voltage division unit; 140-third voltage division unit; 20-first switch unit; 30-first voltage division unit; R1-first voltage division resistor; R2-second voltage division resistor; R3-third voltage division resistor; R4-fourth voltage division resistor; R5-fifth voltage division resistor; R6-sixth voltage division resistor; R7-seventh voltage division resistor; R8-filter resistor; C1-first protection capacitor; C2-second protection capacitor; C3-first filter capacitor; C4-second filter capacitor; Q1-PMOS tube; Q2-triode; D1-protection diode; L1-inductor; A-equipment voltage input end; B-equipment voltage output end. DETAILED DESCRIPTION
[0032] The embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "include" and "have" and any variations thereof used in the specification and the claims and the above description of drawings are intended to cover the inclusion not the exclusion of one or more elements.
[0034] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.
[0035] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0036] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.
[0037] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).
[0038] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.
[0039] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.
[0040] The overvoltage protection circuit is a circuit design for protecting electronic devices and circuits from overvoltage damage, which has been widely used in power protection, communication equipment, household appliances, battery management systems and other application occasions. Its main function is to protect, shunt or limit voltage through specific components, to ensure that the circuit, device and its components are not affected by overvoltage when the voltage in the circuit exceeds the safe working range. Generally, the overvoltage protection circuit is installed at the power input end or the important load end, which can quickly respond to voltage changes, thereby achieving the effect of preventing the device from being damaged.
[0041] At present, there are some overvoltage protection circuits on the market, but these circuits often have the problem of low protection accuracy. For example, some overvoltage protection circuits use a simple voltage comparator to detect overvoltage conditions, but due to the limited accuracy of the voltage comparator itself, false positives or false negatives can easily occur. Therefore, a more accurate and relatively simple overvoltage protection circuit is needed to meet the needs of practical applications.
[0042] To address the aforementioned issues, this application designs an overvoltage protection circuit and its power supply system for the equipment. The circuit uses a first voltage divider unit to divide the output voltage of the equipment and transmits the divided voltage to a reference voltage control unit. When the obtained divided voltage differs from its own reference voltage, the reference voltage control unit precisely controls the on / off state of the first switching unit, thereby improving the accuracy of overvoltage protection. Furthermore, the reference voltage control unit designed in this scheme can adjust the pre-stored reference voltage based on the voltage condition of the protected equipment, thus improving the adaptability of the overvoltage protection. Additionally, the first switching unit in this scheme uses a PMOS transistor, and the reference voltage control unit uses a transistor to control the first switching unit. This rapid switching between the PMOS transistor and the transistor ensures that the circuit can quickly respond to overvoltage events, improving the efficiency of overvoltage protection.
[0043] Based on the above ideas, this application first provides an overvoltage protection circuit, such as... Figure 1 As shown, the overvoltage protection circuit includes a reference voltage control unit 10, a first switching unit 20, and a first voltage divider unit 30. The input terminal of the first switching unit 20 is electrically connected to the device voltage input terminal A, and the output terminal of the first switching unit 20 is electrically connected to the device voltage output terminal B. The control terminal of the first switching unit 20 is electrically connected to the output terminal of the reference voltage control unit 10. The reference terminal of the reference voltage control unit 10 is electrically connected to the device voltage output terminal B through the first voltage divider unit 30, and the input terminal of the reference voltage control unit 10 is grounded. The reference voltage control unit 10 represents a device unit composed of a reference voltage chip, which can also be called a voltage reference chip. It conducts an output signal when the received voltage is greater than or equal to its own reference voltage, and does not conduct or output a signal when the received voltage is less than its own reference voltage.
[0044] The overvoltage protection circuit designed above operates normally as follows: When the output voltage Vout at the device voltage output terminal B is normal, the first voltage divider unit 30 divides the output voltage Vout. The divided voltage from the first voltage divider unit 30 is transmitted to the reference voltage control unit 10. At this time, assuming that the divided voltage obtained by the reference voltage control unit 10 is less than its own reference voltage, the reference voltage control unit 10 controls the first switch unit 20 to be turned on. The voltage at the device voltage input terminal A is normally transmitted to the device voltage output terminal B through the turned-on first switch unit 20. The device voltage output terminal B transmits the output voltage Vout to the device to supply power to the electrical equipment.
[0045] The overvoltage protection circuit designed above has an overvoltage working state: when the output voltage Vout of the device voltage output end B is too high, the reference voltage control unit 10 controls the first switch unit to be cut off, the connection between the device voltage input end A and the device voltage output end B is cut off, and the input voltage Vin of the device voltage input end A is transmitted to the ground, so as to protect the electrical equipment from damage caused by the overvoltage.
[0046] The overvoltage protection circuit designed above has an overvoltage working state: when the output voltage Vout of the device voltage output end B is too high, the reference voltage control unit 10 controls the first switch unit to be cut off, the connection between the device voltage input end A and the device voltage output end B is cut off, and the input voltage Vin of the device voltage input end A is transmitted to the ground, so as to protect the electrical equipment from damage caused by the overvoltage.
[0047] In an optional embodiment of the present embodiment, the first voltage dividing unit 30 designed in the present solution can be a voltage dividing unit composed of resistors in series, as shown in Figure 2 Specifically, the first voltage dividing unit 30 can include a first voltage dividing resistor R1 and a second voltage dividing resistor R2, a first end of the first voltage dividing resistor R1 is electrically connected with the device voltage output end B, a second end of the first voltage dividing resistor R1 is electrically connected with a first end of the second voltage dividing resistor R2 and a reference end of the reference voltage control unit 10 respectively, and a second end of the second voltage dividing resistor R2 is grounded.
[0048] In the above embodiment, the present solution realizes the voltage division of the output voltage Vout of the device voltage output end B through the first voltage dividing resistor R1 and the second voltage dividing resistor R2, so as to provide a suitable voltage for the reference voltage control unit 10, thereby avoiding the case that the output voltage Vout is too large to exceed the rated voltage of the reference voltage control unit 10, and thereby causing damage to the reference voltage control unit 10.
[0049] In the above embodiment, the present solution forms the first voltage dividing unit through the simple structure of two voltage dividing resistors, so as to provide a suitable voltage for the reference voltage control unit, thereby simplifying the circuit structure and reducing the circuit cost.
[0050] In an optional embodiment of the present embodiment, as a possible embodiment, as shown in Figure 3As shown, the reference voltage control unit 10 designed in the scheme includes a reference voltage chip 110, a second switch unit 120, a second voltage dividing unit 130, and a third voltage dividing unit 140, wherein the second voltage dividing unit 130 and the third voltage dividing unit 140 are connected in parallel, the input ends of the second voltage dividing unit 130 and the third voltage dividing unit 140 are electrically connected with the device voltage input end A, the output end of the second voltage dividing unit 130 is electrically connected with the control end of the first switch unit 20, the ground end of the second voltage dividing unit 130 is electrically connected with the input end of the second switch unit 120, the first output end of the third voltage dividing unit 140 is electrically connected with the cathode of the reference voltage chip 110, the second output end of the third voltage dividing unit 140 is electrically connected with the control end of the second switch unit 120, the ground end of the third voltage dividing unit 140, the anode of the reference voltage chip 110, and the output end of the second switch unit 120 are grounded, and the reference end of the reference voltage chip 110 is electrically connected with the device voltage output end B through the first voltage dividing unit 30. In the scheme, the reference voltage chip 110 can be any type of reference voltage chip on the market, for example, any one of a reference voltage chip based on a bandgap reference principle, a reference voltage chip based on a Zener diode principle, and a reference voltage chip based on a charge pump principle.
[0051] In the normal working state of the overvoltage protection circuit, when the output voltage Vout of the device voltage output end B is normal, the first voltage dividing unit 30 divides the output voltage Vout, and the divided voltage of the first voltage dividing unit 30 is transmitted to the reference voltage chip 110. The divided voltage obtained by the reference voltage chip 110 is less than the reference voltage of the reference voltage chip 110 itself, at which time the reference voltage chip 110 is not turned on. Since the reference voltage chip is not turned on, the voltage obtained by the third voltage dividing unit 140 from the input voltage Vin is transmitted to the control end of the second switch unit 120. Since the voltage is greater than the turn-on voltage of the second switch unit 120, the second switch unit 120 is turned on. Since the second switch unit 120 is turned on, the voltage received by the control end of the first switch unit 20 is the divided voltage obtained by the second voltage dividing unit 130 from the input voltage Vin, and the voltage received by the input end of the first switch unit 20 is the input voltage Vin. At this time, since the voltage at the input end is greater than the voltage at the control end of the first switch unit 20, the turn-on condition of the first switch unit 20 is met, the device voltage input end A transmits the voltage to the device voltage output end B through the first switch unit 20, and the device voltage output end B transmits the output voltage Vout to the device to supply power to the device.
[0052] In the overvoltage working state of the overvoltage protection circuit, when the output voltage Vout of the device voltage output terminal B is too high, the first voltage dividing unit 30 divides the output voltage Vout, and the divided voltage is transmitted to the reference voltage chip 110. The divided voltage obtained by the reference voltage chip 110 is greater than or equal to the reference voltage of the reference voltage chip 110 itself. At this time, the reference voltage chip 110 is turned on. Since the reference voltage chip is turned on, the third voltage dividing unit 140 is grounded through the reference voltage chip, and the voltage value transmitted to the control end of the second switch unit 120 is 0. At this time, the voltage at the control end of the second switch unit 120 is less than the turn-on voltage of the second switch unit 120, so the second switch unit 120 is not turned on. Since the second switch unit 120 is not turned on, the voltage received by the control end of the first switch unit 20 is the input voltage Vin, and the voltage received by the input end of the first switch unit 20 is the input voltage Vin. At this time, since the input end voltage is equal to the voltage at the control end of the first switch unit 20, the turn-on condition of the first switch unit 20 is not met, and the device voltage input terminal A cannot transmit the voltage to the device voltage output terminal B through the first switch unit 20, thereby cutting off the connection between the device voltage input terminal A and the device voltage output terminal B, and transmitting the input voltage Vin of the device voltage input terminal A to the ground through the third voltage dividing unit 140 and the reference voltage chip 110, thereby protecting the electrical equipment from damage caused by excessive voltage.
[0053] In an optional embodiment of the present embodiment, as shown in Figure 4 the first switch unit 20 can be a PMOS tube Q1, the second switch unit 120 can be a triode Q2, and the second voltage dividing unit 130 includes a third voltage dividing resistor R3 and a fourth voltage dividing resistor R4. The first end of the third voltage dividing resistor R3 is electrically connected to the device voltage input terminal A, the second end of the third voltage dividing resistor R3 is electrically connected to the gate of the PMOS tube Q1 and the first end of the fourth voltage dividing resistor R4, and the second end of the fourth voltage dividing resistor R4 is electrically connected to the collector of the triode Q2. The third voltage dividing unit 140 includes a fifth voltage dividing resistor R5, a sixth voltage dividing resistor R6, and a seventh voltage dividing resistor R7. The first end of the fifth voltage dividing resistor R5 is electrically connected to the device voltage input terminal A, the second end of the fifth voltage dividing resistor R5 is electrically connected to the first end of the sixth voltage dividing resistor R6 and the cathode of the reference voltage chip 110, the second end of the sixth voltage dividing resistor R6 is electrically connected to the first end of the seventh voltage dividing resistor R7 and the base of the triode Q2, and the second end of the seventh voltage dividing resistor R7 is grounded. In this scheme, the third voltage dividing resistor R3 not only divides the input voltage Vin, but also plays a role in preventing ESD static electricity, avoiding a high resistance state, and acting as a discharge resistor to prevent the PMOS tube Q1 from malfunctioning and damaging the gate and source of the PMOS tube.
[0054] The implementation of the above design, the normal working state of the overvoltage protection circuit: when the output voltage Vout of the device voltage output end B is normal, the first voltage dividing unit 30 divides the output voltage Vout, and the voltage dividing of the first voltage dividing unit 30 is transmitted to the reference voltage chip 110. The voltage dividing voltage obtained by the reference voltage chip 110 is less than the reference voltage of the reference voltage chip 110 itself. At this time, the reference voltage chip 110 is not turned on. Since the reference voltage chip 110 is not turned on, at this time Figure 4 The voltage at point A in the above formula is the voltage dividing of the fifth voltage dividing resistor R5, the sixth voltage dividing resistor R6 and the seventh voltage dividing resistor R7, which is a high level. The high level voltage is transmitted to the base of the transistor Q2 through the sixth voltage dividing resistor. Since it is greater than the turn-on voltage of the transistor Q2, the transistor Q2 is turned on. Since the transistor Q2 is turned on, the voltage received by the gate of the PMOS tube Q1 is the voltage dividing voltage obtained by dividing the input voltage Vin by the third voltage dividing resistor R3 and the fourth voltage dividing resistor R4, and the voltage received by the source of the PMOS tube Q1 is the input voltage Vin. At this time, since the gate voltage is less than the source voltage, the turn-on condition of the PMOS tube Q1 is met. The device voltage input end A transmits the voltage to the voltage output end B of the device through the PMOS tube Q1, and the device voltage output end B transmits the output voltage Vout to the device to supply power to the power device.
[0055] The implementation of the above design, the overvoltage working state of the overvoltage protection circuit: when the output voltage Vout of the device voltage output end B is too high, the first voltage dividing unit 30 divides the output voltage Vout, and the voltage dividing of the first voltage dividing unit 30 is transmitted to the reference voltage chip 110. The voltage dividing voltage obtained by the reference voltage chip 110 is greater than or equal to the reference voltage of the reference voltage chip 110 itself. At this time, the reference voltage chip 110 is turned on. Since the reference voltage chip 110 is turned on, at this time the fifth voltage dividing resistor R5 is grounded through the reference voltage chip 110. Therefore, the voltage value transmitted to the base of the transistor Q2 is 0. At this time, the base voltage of the transistor Q2 is less than the turn-on voltage of the transistor Q2. Therefore, the transistor Q2 is not turned on. Since the transistor Q2 is not turned on, the voltage received by the gate of the PMOS tube Q1 is the input voltage Vin, and the voltage received by the source of the PMOS tube is the input voltage Vin. At this time, since the gate voltage is equal to the source voltage, the turn-on condition of the PMOS tube Q1 is not met. The device voltage input end A cannot transmit the voltage to the voltage output end B of the device through the PMOS tube Q1, thereby cutting off the connection between the device voltage input end A and the device voltage output end B, and transmitting the input voltage Vin of the device voltage input end A to the ground through the fifth voltage dividing resistor R5 and the reference voltage chip 110, thereby protecting the power device from damage caused by overvoltage.
[0056] In the above embodiment, the first switch unit is designed by using a PMOS tube, and the reference voltage control unit is designed by using a transistor to control the first switch unit, so that the circuit can quickly respond to an overvoltage event through the rapid switching of the PMOS tube and the transistor, and the efficiency of overvoltage protection is improved.
[0057] In an optional embodiment of the present embodiment, as shown in Figure 5 the overvoltage protection circuit can further include a protection diode D1, a positive electrode of the protection diode D1 being electrically connected to the gate of the PMOS tube Q1, and a negative electrode of the protection diode D1 being electrically connected to the device voltage input end A.
[0058] The protection diode D1 can protect the gate and the source of the PMOS tube Q1. Since the MOSFET is an insulated gate field effect tube, the gate has no direct current path and has high input impedance, and is prone to cause static charge accumulation, thereby generating a high voltage to break down the insulation layer between the gate and the source. The protection diode D1 can embed the static electricity below the voltage stabilizing value, and effectively protect the insulation layer of the gate and the source.
[0059] In an optional embodiment of the present embodiment, in order to improve the stability and reliability of the overvoltage protection circuit, as shown in Figure 6 the overvoltage protection circuit can further include a first protection capacitor C1 and a second protection capacitor C2, the first protection capacitor C1 being connected in parallel with the sixth voltage dividing resistor R6, and the second protection capacitor C2 being connected in parallel with the first voltage dividing resistor R1.
[0060] In an optional embodiment of the present embodiment, in order to improve the stability and reliability of the overvoltage protection circuit, as shown in Figure 7 the overvoltage protection circuit can further include a filter unit, the filter unit being arranged between the PMOS tube Q1 and the device voltage output end B.
[0061] Please continue to refer to Figure 7 the filter unit can be composed of an inductor L1, a filter resistor R8, a first filter capacitor C3, and a second filter capacitor C4, so as to suppress the transient current and noise between the PMOS tube Q1 and the device voltage output end B, thereby improving the anti-interference ability of the designed overvoltage protection circuit.
[0062] The present application also provides a power supply system for an electric device, which can include the overvoltage protection circuit of any of the optional embodiments described above.
[0063] The power supply system for the electrical equipment designed above, since it contains the overvoltage protection circuit described above, the power supply system for the electrical equipment designed above performs voltage division on the equipment output voltage through the first voltage division unit, and transmits the voltage division to the reference voltage control unit, the reference voltage control unit realizes accurate control of the on / off of the first switch unit in the case that the obtained voltage division is different from the reference voltage of the reference voltage control unit, so as to improve the accuracy of overvoltage protection based on the voltage division obtained by the reference voltage control unit and the reference voltage of the reference voltage control unit.
[0064] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.
Claims
1. An overvoltage protection circuit, characterized by, The application relates to a reference voltage control unit, a first switch unit and a first voltage dividing unit. An input end of the first switch unit is electrically connected with a device voltage input end, an output end of the first switch unit is electrically connected with a device voltage output end, a control end of the first switch unit is electrically connected with an output end of the reference voltage control unit, and a reference end of the reference voltage control unit is electrically connected with the device voltage output end through the first voltage dividing unit. The reference voltage control unit is configured to control the first switch unit to be cut off when a received voltage dividing voltage is greater than or equal to a reference voltage of the reference voltage control unit, and control the first switch unit to be turned on when the received voltage dividing voltage is less than the reference voltage of the reference voltage control unit, wherein the voltage dividing voltage is obtained by dividing a device output voltage of the device voltage output end by the first voltage dividing unit. The first voltage dividing unit comprises a first voltage dividing resistor and a second voltage dividing resistor.
2. The overvoltage protection circuit of claim 1, wherein, A first end of the first voltage dividing resistor is electrically connected with the device voltage output end, a second end of the first voltage dividing resistor is electrically connected with a first end of the second voltage dividing resistor and a reference end of the reference voltage control unit respectively, and a second end of the second voltage dividing resistor is grounded. The reference voltage control unit comprises a reference voltage chip, a second switch unit, a second voltage dividing unit and a third voltage dividing unit.
3. The overvoltage protection circuit of claim 1, wherein, The second voltage dividing unit and the third voltage dividing unit are connected in parallel, and input ends of the second voltage dividing unit and the third voltage dividing unit are electrically connected with the device voltage input end. An output end of the second voltage dividing unit is electrically connected with the control end of the first switch unit, and a grounding end of the second voltage dividing unit is electrically connected with an input end of the second switch unit. A first output end of the third voltage dividing unit is electrically connected with a cathode of the reference voltage chip, and a second output end of the third voltage dividing unit is electrically connected with a control end of the second switch unit. A grounding end of the third voltage dividing unit, an anode of the reference voltage chip and an output end of the second switch unit are grounded, and a reference end of the reference voltage chip is electrically connected with the device voltage output end through the first voltage dividing unit. The second voltage dividing unit comprises a third voltage dividing resistor and a fourth voltage dividing resistor.
4. The overvoltage protection circuit of claim 3, wherein, A first end of the third voltage dividing resistor is electrically connected with the device voltage input end, a second end of the third voltage dividing resistor is electrically connected with the control end of the first switch unit and a first end of the fourth voltage dividing resistor respectively, and a second end of the fourth voltage dividing resistor is electrically connected with the input end of the second switch unit. The third voltage dividing unit comprises a fifth voltage dividing resistor, a sixth voltage dividing resistor and a seventh voltage dividing resistor, a first end of the fifth voltage dividing resistor is electrically connected with the device voltage input end, a second end of the fifth voltage dividing resistor is electrically connected with a first end of the sixth voltage dividing resistor and a cathode of the reference voltage chip respectively, a second end of the sixth voltage dividing resistor is electrically connected with a first end of the seventh voltage dividing resistor and the control end of the second switch unit respectively, and a second end of the seventh voltage dividing resistor is grounded.
5. The overvoltage protection circuit of claim 4, wherein, The first switch unit comprises a PMOS tube, and the second switch unit is a triode.
6. The overvoltage protection circuit of claim 5, wherein, The gate of the PMOS tube is electrically connected with the second end of the third voltage dividing resistor and the collector of the transistor respectively, the source of the PMOS tube is electrically connected with the equipment voltage input end, and the drain of the PMOS tube is electrically connected with the equipment voltage output end. The emitter of the transistor is grounded, and the base of the transistor is electrically connected with the second end of the sixth voltage dividing resistor.
7. The overvoltage protection circuit of claim 6, wherein, The overvoltage protection circuit further comprises a protection diode. The anode of the protection diode is electrically connected with the gate of the PMOS tube, and the cathode of the protection diode is electrically connected with the equipment voltage input end.
8. The overvoltage protection circuit of claim 5, wherein, The overvoltage protection circuit further comprises a first protection capacitor and a second protection capacitor. The first protection capacitor is connected in parallel with the sixth voltage dividing resistor, and the second protection capacitor is connected in parallel with the first voltage dividing unit.
9. The overvoltage protection circuit of claim 1, wherein, The overvoltage protection circuit further comprises a filtering unit. The filtering unit is arranged between the first switching unit and the equipment voltage output end.
10. A power supply system for electrical equipment, characterized in that, The power supply system of the electrical equipment comprises the overvoltage protection circuit according to any one of claims 1-9.