Overvoltage protection circuit, power supply circuit and electronic equipment

Abstract

The utility model discloses an overvoltage protection circuit, a power supply circuit and electronic equipment, and belongs to the field of overvoltage protection, and the overvoltage protection circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, a second triode, a third triode and a voltage comparator. When the signal of the output electrode, namely the state output end, of the second triode is low level, the voltage of the direct-current power supply does not exceed the preset voltage value, and the overvoltage protection circuit does not disconnect the connection between the direct-current power supply and the load; and when the signal of the output electrode, namely the state output end, of the second triode is high level, the voltage of the direct-current power supply exceeds the preset voltage value, and the overvoltage protection circuit disconnects the direct-current power supply from the load. According to the scheme, the working state of the power supply protection circuit can be provided while an overvoltage protection chip is not used, the cost is low, and use by a user is facilitated.

Description

Technical Field

[0001] The utility model relates to the field of overvoltage protection, in particular to an overvoltage protection circuit, a power supply circuit and an electronic device. Background Art

[0002] There are many hardware protection solutions for power supply circuits nowadays. Those with ample budgets can directly use overvoltage protection chips, but their adjustable overvoltage range is relatively small. Under cost constraints, the following two methods are generally used:

[0003] The first type is a Zener diode. When the input voltage exceeds the Zener diode's voltage regulation value, the Zener diode starts to conduct and introduces the excess voltage into the ground, thereby limiting the voltage across the protected circuit to not exceed the voltage regulation value.

[0004] The second type is an overvoltage protection circuit that uses a fuse and a current-limiting resistor. When the voltage in the circuit exceeds a certain value, the current-limiting resistor will limit the current, thereby preventing the components in the circuit from being damaged due to overcurrent. At the same time, the fuse will melt when the current is too large, cutting off the circuit and further protecting the components in the circuit from damage.

[0005] However, these two overvoltage protection solutions cannot provide users with the working status of the overvoltage protection circuit when in use, resulting in a poor user experience. Utility Model Content

[0006] In order to overcome the deficiencies of the prior art, the utility model provides an overvoltage protection circuit, a power supply circuit and an electronic device to solve the problem that when the overvoltage protection chip is not used, the working status of the overvoltage protection circuit cannot be provided to the user, resulting in poor user experience.

[0007] The technical solution adopted by the utility model to solve its technical problems is:

[0008] In a first aspect, an overvoltage protection circuit is provided, comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a first transistor, a second transistor, a third transistor and a voltage comparator;

[0009] The first resistor and the second resistor are connected in series between the positive electrode and the negative electrode of the DC power supply;

[0010] The first end of the third resistor is connected to the positive electrode of the DC power supply, the second end of the third resistor is connected to the base of the first transistor, the third electrode of the first transistor is connected to the positive electrode of the DC power supply, and the output electrode of the first transistor is a voltage output end for supplying power to a load;

[0011] The connection point between the first resistor and the second resistor is connected to the first input terminal of the voltage comparator, the reference voltage is input to the second input terminal of the voltage comparator, and the output terminal of the voltage comparator is connected to the base of the third transistor; the output terminal of the third transistor is connected to the negative electrode of the DC power supply, and the third electrode of the third transistor is connected to the second end of the third resistor;

[0012] The base of the second transistor is connected to the third electrode of the third transistor, the third electrode of the second transistor is connected to the positive electrode of the DC power supply, the output electrode of the second transistor is connected to the negative electrode of the DC power supply through the fourth resistor, and the output electrode of the second transistor is a status output terminal for sending a status prompt signal;

[0013] Among them, when the transistor is of NPN type, the output pole is the emitter and the third pole is the collector. When the transistor is of PNP type, the output pole is the collector and the third pole is the emitter.

[0014] Furthermore, a surge protection device is provided between the positive electrode of the DC power supply and the negative electrode of the DC power supply.

[0015] Further, it also includes: a first diode;

[0016] The overvoltage protection circuit is connected to the cathode of the DC power supply through the first diode, and the cathode of the first diode is connected to the cathode of the DC power supply.

[0017] Furthermore, the first diode is a light emitting diode.

[0018] Furthermore, it also includes: a fifth resistor;

[0019] The second end of the third resistor is connected to the base of the first transistor through the fifth resistor.

[0020] Furthermore, it also includes: a sixth resistor;

[0021] The base of the second transistor is connected to the third electrode of the third transistor through the sixth resistor.

[0022] Furthermore, it also includes: a seventh resistor;

[0023] The third electrode of the second transistor is connected to the positive electrode of the DC power supply through the seventh resistor.

[0024] Further, it also includes: a second diode;

[0025] The second diode is arranged at the output electrode of the first transistor, and the anode of the second diode is connected to the output electrode of the first transistor.

[0026] In a second aspect, a power supply circuit is provided, including a first power supply and a second power supply, wherein at least one of the first power supply and the second power supply is a DC power supply;

[0027] The DC power supply uses the above-mentioned overvoltage protection circuit to supply power to the load.

[0028] In a third aspect, an electronic device is provided, which adopts the above-mentioned power supply circuit.

[0029] This application adopts the above technical solution, which has at least the following beneficial effects:

[0030] The technical solution of the present application provides an overvoltage protection circuit, a power supply circuit and an electronic device, wherein the overvoltage protection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first transistor, a second transistor, a third transistor and a voltage comparator, and the first resistor and the second resistor divide the voltage. When the voltage of the DC power supply is higher than the preset voltage value, the second resistor divides the voltage greater than the reference voltage, at which time the voltage comparator outputs a high level, the third transistor is turned on, and the level at the third pole of the third transistor is low, that is, the base level of the first transistor is low, and the first transistor cannot be turned on, which is equivalent to the first transistor disconnecting the DC power supply from the voltage output terminal, and the DC power supply cannot supply power to the load; at this time, the base level of the second transistor is low, the second transistor cannot be turned on, and the output level of the output pole of the second transistor is low. When the voltage of the DC power supply is not higher than the preset voltage value, the second resistor voltage is not greater than the reference voltage. At this time, the voltage comparator outputs a low level, the third transistor is not turned on, the level at the third pole of the third transistor is higher, the first transistor is turned on, and the positive pole of the DC power supply supplies power to the load through the third pole and the output pole of the first transistor in turn; at this time, the base level of the second transistor is higher, the second transistor is turned on, and the output pole of the second transistor outputs a high level signal. In this way, when the signal at the output pole of the second transistor, that is, the state output end, is low, it means that the DC power supply voltage does not exceed the preset voltage value, and the overvoltage protection circuit does not disconnect the DC power supply from the load; and when the signal at the output pole of the second transistor, that is, the state output end, is high, it means that the DC power supply voltage exceeds the preset voltage value, and the overvoltage protection circuit disconnects the DC power supply from the load. The present application scheme can provide the working state of the power protection circuit without using an overvoltage protection chip, and has low cost and is convenient for users to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application 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 present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is a schematic diagram of an overvoltage protection circuit structure provided by an embodiment of the utility model;

[0033] Figure 2 This is a schematic diagram of a specific overvoltage protection circuit structure provided by an embodiment of the utility model;

[0034] Figure 3 This is a schematic diagram of a power supply structure provided by an embodiment of the utility model. Description of the drawings:

[0036] R1-first resistor;

[0037] R2-second resistor;

[0038] R3-the third resistor;

[0039] R4-the fourth resistor;

[0040] R5-fifth resistor;

[0041] R6-sixth resistor;

[0042] R7-seventh resistor;

[0043] Q1-the first transistor;

[0044] Q2-the second transistor;

[0045] Q3-the third transistor;

[0046] U1- voltage comparator;

[0047] Vref - reference voltage

[0048] TVS-transient voltage suppression tube;

[0049] D1-first diode;

[0050] D2-second diode;

[0051] VCC1-first power supply;

[0052] VCC2-second power supply;

[0053] 31-overvoltage protection circuit;

[0054] 32-Load. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present utility model is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0056] Today's overvoltage protection circuits either use overvoltage protection chips, which can inform users of the working status of the overvoltage protection circuit while providing overvoltage protection functions (such as when the overvoltage protection circuit is in the first working state, it means that the power supply voltage is normal, the overvoltage protection circuit does not work at this time, and the power supply normally supplies power to the load; and when the overvoltage protection circuit is in the second working state, it means that the power supply voltage is too high, the overvoltage protection circuit works, and the power supply to the load is cut off), so that users know the power supply situation and take corresponding measures. However, the cost of overvoltage protection chips is relatively high. The overvoltage protection circuit composed of low-cost electronic components can only provide overvoltage protection functions, and cannot inform users of the working status of the overvoltage protection circuit, so that users cannot know the power supply situation and cannot take further measures.

[0057] Reference Figure 1 , the embodiment of the utility model provides an overvoltage protection circuit, including a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, a second transistor Q2, a third transistor Q3 and a voltage comparator U1;

[0058] The first resistor R1 and the second resistor R2 are connected in series between the positive electrode and the negative electrode of the DC power supply; the first resistor R1 and the second resistor R2 play the role of voltage division. Since the resistance values ​​of the first resistor R1 and the second resistor R2 are fixed, the voltage V at the second resistor R2 R2 It can represent the voltage V of the DC power supply. The relationship between the two is V R2 =V*R2 / (R1+R2).

[0059] The first end of the third resistor R3 is connected to the positive electrode of the DC power supply, the second end of the third resistor R3 is connected to the base of the first transistor Q1, the third electrode of the first transistor Q1 is connected to the positive electrode of the DC power supply, and the output electrode of the first transistor Q1 is a voltage output end for supplying power to the load; when the first transistor Q1 is turned on, the current flows from the third electrode of the first transistor Q1 to the output electrode of the first transistor Q1, that is, the DC power supply can supply power to the load through the voltage output end; when the first transistor Q1 cannot be turned on, the current cannot flow from the third electrode of the first transistor Q1 to the output electrode of the first transistor Q1, and the DC power supply cannot supply power to the load through the voltage output end.

[0060] The connection point of the first resistor R1 and the second resistor R2 is connected to the first input end of the voltage comparator U1, the second input end of the voltage comparator U1 inputs the reference voltage Vref, and the output end of the voltage comparator U1 is connected to the base of the third transistor Q3; the output electrode of the third transistor Q3 is connected to the negative electrode of the DC power supply, and the third electrode of the third transistor Q3 is connected to the second end of the third resistor R3.

[0061] Since the voltage at the second resistor R2 can represent the voltage of the DC power supply, the voltage input to the first input terminal of the voltage comparator U1 is the voltage of the second resistor R2, and the reference voltage Vref is input to the second input terminal of the voltage comparator U1. Thus, when the voltage of the DC power supply is high, the voltage at the first input terminal of the voltage comparator U1 is greater than the voltage at the second input terminal, and the output terminal of the voltage comparator U1 outputs a high level, that is, the base of the third transistor Q3 is at a high level, and based on the conduction characteristic of the transistor, the third transistor Q3 is turned on. At this time, it is equivalent to that the third electrode of the third transistor Q3 is connected to the input electrode, and the positive electrode of the DC power supply is directly connected to the negative electrode of the DC power supply through the third electrode of the third transistor Q3 and the input electrode after passing through the third resistor R3, so that the level at the third electrode of the third transistor Q3 is 0; that is, the base of the first transistor Q1 is 0 at this time, and the first transistor Q1 cannot be turned on, and the current cannot flow from the third electrode of the first transistor Q1 to the output electrode of the first transistor Q1, and the DC power supply cannot supply power to the load through the voltage output terminal. That is, when the voltage of the DC power supply is high (ie, when an overvoltage occurs), the line through which the DC power supply supplies power to the load can be directly cut off through the voltage comparator U1, the third transistor Q3 and the first transistor Q1.

[0062] When the voltage of the DC power supply is low, the voltage of the first input terminal of the voltage comparator U1 is not greater than the voltage of the second input terminal, and the output terminal of the voltage comparator U1 outputs a low level, that is, the base of the third transistor Q3 is a low level, and based on the conduction characteristics of the transistor, the third transistor Q3 cannot be turned on. At this time, it is equivalent to that the third pole of the third transistor Q3 is disconnected from the input pole, and the positive pole of the DC power supply cannot be directly connected to the negative pole of the DC power supply through the third pole and the input pole of the third transistor Q3 after passing through the third resistor R3, so that the level at the third pole of the third transistor Q3 is higher; that is, the base of the first transistor Q1 is at a higher level at this time, the first transistor Q1 is turned on, and the current can flow from the third pole of the first transistor Q1 to the output pole of the first transistor Q1, and the DC power supply can supply power to the load through the voltage output terminal. That is, when the voltage of the DC power supply is low (that is, when there is no overvoltage), the first transistor Q1 will not affect the line of the DC power supply supplying power to the load.

[0063] The base of the second transistor Q2 is connected to the third electrode of the third transistor Q3, the third electrode of the second transistor Q2 is connected to the positive electrode of the DC power supply, the output electrode of the second transistor Q2 is connected to the negative electrode of the DC power supply through the fourth resistor R4, and the output electrode of the second transistor Q2 is a status output terminal for sending a status prompt signal;

[0064] According to the above logic, when an overvoltage occurs, the level of the third electrode of the third transistor Q3 is 0, that is, the base level of the second transistor Q2 is 0 at this time, and the second transistor Q2 cannot be turned on. At this time, the output electrode of the second transistor Q2, that is, the level of the state output end, is 0; when no overvoltage occurs, the level of the third electrode of the third transistor Q3 is higher, that is, the base level of the second transistor Q2 is higher at this time, and the second transistor Q2 is turned on. At this time, the output electrode of the second transistor Q2, that is, the level of the state output end, is higher.

[0065] Among them, when the transistor is of NPN type, the output pole is the emitter and the third pole is the collector. When the transistor is of PNP type, the output pole is the collector and the third pole is the emitter.

[0066] In order to more specifically describe the solution of this application, Figure 2 As shown, the present application provides a more specific overvoltage protection circuit, wherein the first transistor Q1 and the third transistor Q3 are NPN transistors, and the second transistor Q2 is a PNP transistor, including: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first diode D1, a second diode D2, a first transistor Q1, a second transistor Q2, a third transistor Q3 and a voltage comparator U1.

[0067] The positive electrode of the DC power supply is connected to the positive electrode of the first diode D1 through the first resistor R1 and the second resistor R2 connected in series, and the negative electrode of the first diode D1 is directly connected to the negative electrode of the DC power supply; the first resistor R1 and the second resistor R2 are used for voltage division, and the first diode D1 is used to prevent reverse connection.

[0068] Taking advantage of the forward conduction and reverse cutoff characteristics of the diode, the first diode D1 is selected to be connected in series at the negative terminal of the DC power supply. When the DC power supply is reversely connected, the first diode D1 is in the cutoff state and cannot form a loop. When selecting the first diode D1, it is necessary to pay attention to the reverse effective value voltage, and it is recommended to reserve a certain margin. The biggest advantage of this method of preventing the reverse connection of the DC power supply is its low cost and simple structure. At the same time, it is also necessary to consider the problems of diode voltage drop and power consumption when the DC power supply is forward-conducted.

[0069] In one embodiment, the first diode D1 is a common diode, which has lower power consumption. However, when the first diode D1 is a common diode, the staff cannot know when the DC power supply is reversely connected.

[0070] Therefore, for the convenience of prompting, in another embodiment, the first diode D1 is a light-emitting diode, so that when the DC power supply is correctly connected, the first diode D1 emits light, and when the DC power supply is reversed, the first diode D1 does not emit light. In this way, the user can know whether the DC power supply is reversed by whether the first diode D1 emits light.

[0071] In addition, for electrical safety, the negative electrode of the DC power supply needs to be grounded. In the embodiment of the present application, since the first diode D1 is provided at the negative electrode access end of the DC power supply, the positive electrode of the first diode D1 can be grounded.

[0072] The first end of the third resistor R3 is connected to the positive electrode of the DC power supply, the second end of the third resistor R3 is connected to the base of the first transistor Q1 through the fifth resistor R5, the collector of the first transistor Q1 is connected to the positive electrode of the DC power supply, and the emitter of the first transistor Q1 is a voltage output end for powering the load through the second diode D2; wherein the positive electrode of the second diode D2 is connected to the emitter of the first transistor Q1, and is used to prevent the current at the load from flowing back to the first transistor Q1 when the voltage output end is connected to the load.

[0073] The connection point of the first resistor R1 and the second resistor R2 is connected to the first input end of the voltage comparator U1, the reference voltage Vref is input to the second input end of the voltage comparator U1, and the output end of the voltage comparator U1 is connected to the base of the third transistor Q3; the emitter of the third transistor Q3 is connected to the negative electrode of the DC power supply, and the collector of the third transistor Q3 is connected to the second end of the third resistor R3;

[0074] The base of the second transistor Q2 is connected to the collector of the third transistor Q3 through the sixth resistor R6, the emitter of the second transistor Q2 is connected to the positive electrode of the DC power supply through the seventh resistor R7, the collector of the second transistor Q2 is connected to the negative electrode of the DC power supply through the fourth resistor R4, and the collector of the second transistor Q2 is a status output terminal for sending a status prompt signal;

[0075] Thus, when the second transistor Q2 is turned on, the voltage at the state output terminal is the voltage at the fourth resistor R4.

[0076] In addition, in order to prevent the DC power supply from generating a large pulse at the moment of being turned on, so that the chip or other parts of the circuit are interfered by the spike, the present application also provides a surge protection device between the positive electrode of the DC power supply and the negative electrode of the DC power supply, such as Figure 2 As shown, a transient voltage suppressor TVS is used. A transient voltage suppressor TVS is connected in parallel to the positive and negative electrodes of the DC power supply. When a surge pulse voltage appears at the moment the DC power supply is connected, the transient voltage suppressor TVS can quickly break down and change from a high resistance state to a low resistance state, shunting and clamping the surge voltage, thereby protecting the back-end circuit from being damaged by the pulse voltage. At the same time, the transient voltage suppressor TVS has a good electrostatic discharge effect and a fast response speed.

[0077] It should be noted that common surge protection devices also include the following solutions:

[0078] 1. Metal oxide varistor: Usually connected in parallel to the circuit that needs to be protected. When a surge occurs, the metal oxide varistor will turn on and introduce the overvoltage into the ground, thereby protecting the subsequent circuit.

[0079] 2. Surge protection circuit composed of resistors and capacitors: Resistors are used to limit current, while capacitors are used to absorb and store surge energy. However, the effect of this circuit is relatively limited and it is mainly used in situations where surge voltage requirements are not high.

[0080] 3. Other devices: field effect transistor, thermistor, etc.

[0081] The present application scheme realizes anti-surge protection, power reverse connection protection, and overvoltage alarm protection functions through simple hardware circuit design, does not require the use of chips for software development, and improves the reliability of the power supply circuit.

[0082] Based on the same inventive concept, the embodiment of the present application provides a power supply circuit, such as Figure 3 As shown, it includes a first power supply VCC1 and a second power supply VCC2, and at least one of the first power supply and the second power supply is a DC power supply;

[0083] The DC power supply uses the overvoltage protection circuit 31 provided in the above embodiment to supply power to the load 32 .

[0084] Exemplarily, the load is a DC load, and the first power supply and the second power supply are both DC power supplies, wherein the first power supply is based on a standing DC power supply, such as a DC power supply obtained after rectification of the mains; and the second power supply is a standby dry cell battery. The load is a photoelectric encoder, and overvoltage protection is particularly important for the photoelectric encoder, whose power supply circuit consists of two parts: a standing main power supply and an external dry cell battery. When the chip loses the main power supply, the chip enters the voltage condition provided by the dry cell battery and records real-time multi-turn value data. When the photoelectric chip is powered by a dry cell battery, when the dry cell battery voltage does not meet the power supply conditions, the chip loses data, and in severe cases, the chip may be damaged.

[0085] The photoelectric chip of the photoelectric encoder needs to be combined with a dry battery to store multi-turn data. A large pulse may be generated at the moment the battery is connected, causing spike interference to the chip or other parts of the circuit. Moreover, when replacing the dry battery, there may be reverse connection or excessive battery voltage output, causing damage to components or even more serious consequences.

[0086] By adopting the overvoltage protection circuit provided in the above-mentioned embodiment of the present application, anti-surge protection, battery reverse connection protection, and battery overvoltage alarm protection functions can be implemented through simple hardware circuit design, thereby improving the reliability of the photoelectric encoder operating under dry battery conditions.

[0087] It is understandable that when the load is an AC load, an inverter needs to be connected after the overvoltage protection circuit; and when the load is a DC load but the first power supply or the second power supply is an AC power supply, the AC power supply and the load need to be directly connected to a rectifier.

[0088] The power supply circuit provided by the embodiment of the present application uses the overvoltage protection circuit provided by the above embodiment. When the signal at the output pole of the second triode, i.e., the state output terminal, is at a low level, it indicates that the DC power supply voltage does not exceed the preset voltage value, and the overvoltage protection circuit does not disconnect the DC power supply from the load; and when the signal at the output pole of the second triode, i.e., the state output terminal, is at a high level, it indicates that the DC power supply voltage exceeds the preset voltage value, and the overvoltage protection circuit disconnects the DC power supply from the load. The present application scheme can provide the working state of the power supply protection circuit without using an overvoltage protection chip, and has low cost and is convenient for users to use.

[0089] Based on the same inventive concept, the present application provides an electronic product, which adopts the power supply circuit provided by the above embodiment.

[0090] The electronic product provided in the embodiment of the present application, by using the power supply circuit provided in the above embodiment, can achieve overvoltage protection when at least one of the first power supply and the second power supply is a DC power supply, thereby ensuring the safety and reliability of the electronic product.

[0091] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0092] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0093] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0094] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0095] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0096] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0097] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0098] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0099] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An overvoltage protection circuit, characterized in that: It includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, a second triode, a third triode and a voltage comparator; The first resistor and the second resistor are connected in series between the positive electrode and the negative electrode of the DC power supply; The first end of the third resistor is connected to the positive electrode of the DC power supply, the second end of the third resistor is connected to the base of the first transistor, the third electrode of the first transistor is connected to the positive electrode of the DC power supply, and the output electrode of the first transistor is a voltage output end for supplying power to a load; The connection point between the first resistor and the second resistor is connected to the first input terminal of the voltage comparator, the reference voltage is input to the second input terminal of the voltage comparator, and the output terminal of the voltage comparator is connected to the base of the third transistor; the output terminal of the third transistor is connected to the negative electrode of the DC power supply, and the third electrode of the third transistor is connected to the second end of the third resistor; The base of the second transistor is connected to the third electrode of the third transistor, the third electrode of the second transistor is connected to the positive electrode of the DC power supply, the output electrode of the second transistor is connected to the negative electrode of the DC power supply through the fourth resistor, and the output electrode of the second transistor is a status output terminal for sending a status prompt signal; Among them, when the transistor is of NPN type, the output pole is the emitter and the third pole is the collector. When the transistor is of PNP type, the output pole is the collector and the third pole is the emitter.

2. The overvoltage protection circuit according to claim 1, characterized in that: A surge protection device is provided between the positive electrode of the DC power supply and the negative electrode of the DC power supply.

3. The overvoltage protection circuit according to claim 1, characterized in that: Also includes: a first diode; The overvoltage protection circuit is connected to the cathode of the DC power supply through the first diode, and the cathode of the first diode is connected to the cathode of the DC power supply.

4. The overvoltage protection circuit according to claim 3, characterized in that: The first diode is a light emitting diode.

5. The overvoltage protection circuit according to claim 1, characterized in that: Also includes: a fifth resistor; The second end of the third resistor is connected to the base of the first transistor through the fifth resistor.

6. The overvoltage protection circuit according to claim 1, characterized in that: Also includes: a sixth resistor; The base of the second transistor is connected to the third electrode of the third transistor through the sixth resistor.

7. The overvoltage protection circuit according to claim 1, characterized in that: Also includes: The seventh resistor; The third electrode of the second transistor is connected to the positive electrode of the DC power supply through the seventh resistor.

8. The overvoltage protection circuit according to claim 1, characterized in that: Also includes: A second diode; The second diode is arranged at the output electrode of the first transistor, and the anode of the second diode is connected to the output electrode of the first transistor.

9. A power supply circuit, characterized in that: It comprises a first power supply and a second power supply, wherein at least one of the first power supply and the second power supply is a DC power supply; The DC power supply uses the overvoltage protection circuit described in any one of claims 1 to 8 to supply power to the load.

10. An electronic device, characterized in that: A power supply circuit as claimed in claim 9 is used.

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