Overvoltage protection circuit and device

Abstract

The utility model relates to an overvoltage protection circuit and device, and the circuit comprises a fuse, one end of which is coupled with a voltage input end; the negative electrode of the transient voltage suppression tube is coupled with the other end of the fuse, and the positive electrode of the transient voltage suppression tube is grounded; the control end of the switch module is coupled with the other end of the fuse, the input end of the switch module is coupled with the voltage input end, and the output end of the switch module is coupled with a voltage output end. According to the overvoltage protection circuit and device provided by the invention, the switch module is additionally arranged in front of the voltage output end of the overvoltage protection circuit, and the fuse is additionally arranged between the transient voltage suppression tube and the voltage input end of the overvoltage protection circuit, so that the fuse can be fused in a continuous overvoltage or transient voltage suppression tube semi-failure state, and the overvoltage protection circuit is protected. The connection between the transient voltage suppressor tube and the voltage input end is cut off, the transient voltage suppressor tube is prevented from continuously heating during overvoltage, safety accidents caused by the transient voltage suppressor tube are avoided, the connection between the voltage input end and the voltage output end is cut off through the switch module, and a post-stage circuit is protected.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to an overvoltage protection circuit and device. Background Art

[0002] At present, traditional circuits that use transient voltage suppressors for overvoltage protection have obvious shortcomings. For example, when the external voltage input device malfunctions and continuously inputs high voltage, the transient voltage suppressor is always in a reverse breakdown state. Or when the transient voltage suppressor is in a semi-failed state for a long time, a large current will continue to pass through the transient voltage suppressor, causing the transient voltage suppressor to continue to heat up, and even burn the surrounding PCB board and device casing, causing fire and other safety accidents. Utility Model Content

[0003] The purpose of this application is to provide an overvoltage protection circuit and device, aiming to solve the problem of potential safety hazards in traditional overvoltage protection circuits based on transient voltage suppressors.

[0004] A first aspect of an embodiment of the present application provides an overvoltage protection circuit, comprising:

[0005] a fuse, one end of the fuse being coupled to a voltage input end;

[0006] a transient voltage suppressor tube, wherein the cathode of the transient voltage suppressor tube is coupled to the other end of the fuse, and the anode of the transient voltage suppressor tube is grounded;

[0007] A switch module, wherein the control end of the switch module is coupled to the other end of the fuse, the input end is coupled to the voltage input end, and the output end is coupled to a voltage output end. The switch module is used to control the electrical connection between the voltage input end and the voltage output end.

[0008] In a possible implementation, the switch module includes:

[0009] a first switch, wherein a control end of the first switch is coupled to the other end of the fuse, and an output end of the first switch is grounded;

[0010] a first resistor, wherein one end of the first resistor is coupled to the voltage input terminal, and the other end of the first resistor is coupled to the input terminal of the first switch;

[0011] The second switch has a control terminal coupled to the input terminal of the first switch, an input terminal coupled to the voltage input terminal, and an output terminal coupled to the voltage output terminal.

[0012] In a possible implementation, the first switch is an NPN transistor, and the second switch is a PMOS transistor.

[0013] In a possible implementation, the overvoltage protection circuit further includes an input-end rectification and filtering module, wherein the input end of the input-end rectification and filtering module is coupled to the voltage input end, and the output end is grounded.

[0014] In a possible implementation, the input-end rectification and filtering module includes: at least one input-end capacitor, one end of the input-end capacitor is coupled to the voltage input end, and the other end is grounded.

[0015] In a possible implementation, the overvoltage protection circuit further includes: an output-end rectification and filtering module, wherein the input end of the output-end rectification and filtering module is coupled to the output end of the switch module, and the output end is grounded.

[0016] In a possible implementation, the output-end rectification and filtering module includes: at least one output-end capacitor, one end of the output-end capacitor is coupled to the voltage input end, and the other end is grounded.

[0017] In a possible implementation, the overvoltage protection circuit further includes: a second resistor, one end of the second resistor is coupled to the output end of the overvoltage signal output module, and the other end of the second resistor is coupled to the first input end of the switch module.

[0018] In a possible implementation, the overvoltage protection circuit further includes: a third resistor, wherein the third resistor is coupled between the output end of the switch module and the voltage output end.

[0019] A second aspect of an embodiment of the present application provides an overvoltage protection device, comprising an overvoltage protection circuit as described in any one of the above items.

[0020] Beneficial effects of this application

[0021] The present application provides an overvoltage protection circuit and device. By adding a switch module in front of the voltage output terminal of the overvoltage protection circuit and adding a fuse between a transient voltage suppressor and the voltage input terminal of the overvoltage protection circuit, when faced with a continuous overvoltage or a semi-failure state of the transient voltage suppressor, the fuse can be blown, cutting off the connection between the transient voltage suppressor and the voltage input terminal, thereby preventing the transient voltage suppressor from continuing to heat up during overvoltage and avoiding safety accidents. At the same time, the switch module is used to cut off the connection between the voltage input terminal and the voltage output terminal, protecting the subsequent circuit from the influence of overvoltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. 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 any creative work.

[0023] Figure 1 It is a structural diagram of a traditional overvoltage protection circuit;

[0024] Figure 2 A schematic diagram of the overvoltage protection circuit structure provided in one embodiment of the present application.

[0025] Description of the drawings: fuse F1, transient voltage suppressor D1, switch module 100, first switch Q1, first resistor R1, second switch Q2, input-end rectifier and filter module 200, output-end rectifier and filter module 300, second resistor R2, third resistor R3, first input-end capacitor C1, second input-end capacitor C2, third input-end capacitor C3, first output-end capacitor C4, second output-end capacitor C5. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0028] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0029] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0030] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0032] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0033] At present, traditional circuits that use transient voltage suppressors for overvoltage protection have obvious shortcomings. For example, when the external voltage input device malfunctions and continuously inputs high voltage, the transient voltage suppressor is always in a reverse breakdown state. Or when the transient voltage suppressor is in a semi-failed state for a long time, a large current will continue to pass through the transient voltage suppressor, causing the transient voltage suppressor to continue to heat up, and even burn the surrounding PCB board and device casing, causing fire and other safety accidents.

[0034] Exemplary, reference Figure 1 The structure diagram of the conventional overvoltage protection circuit is shown in FIG. D2000 is a transient voltage suppressor (TVS), C2003, C2003, C2007, C2008, and C2009 are capacitors, and R2001 is a resistor.

[0035] Specifically, the traditional overvoltage protection circuit requires the working voltage V of the transient voltage suppressor D2000 RWM Equal to 1.1 to 1.2 times the rated working voltage of the protected circuit, while the clamping voltage V CWhen the voltage input terminal VIN is normal, that is, it is less than the working voltage V of the transient voltage suppressor tube. RWM , the transient voltage suppression tube is in high resistance state and does not conduct, and the current can flow normally to the voltage output terminal VOUT; when the voltage input terminal VIN voltage is too high, exceeding the breakdown voltage V BR When the transient voltage suppressor starts to drop rapidly, the impedance of the transient voltage suppressor begins to drop rapidly, absorbing most of the energy quickly, and the voltage output terminal VOUT is clamped to the maximum clamping voltage V C Therefore, when the voltage input terminal VIN continuously inputs high voltage, the transient voltage suppressor (TVS) is always in a reverse breakdown state, or a large current continues to flow through the TVS, causing the TVS to continuously heat up, and even burn the surrounding PCB board and device housing, causing safety accidents such as fire. Therefore, this application proposes a new overvoltage protection circuit and device to solve the above problems.

[0036] In order to illustrate the technical solution of the present application, specific embodiments are provided below.

[0037] Figure 2 The structure diagram of the overvoltage protection circuit provided by the preferred embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0038] a fuse F1, wherein one end of the fuse F1 is coupled to a voltage input end VIN;

[0039] a transient voltage suppressor D1, wherein the cathode of the transient voltage suppressor D1 is coupled to the other end of the fuse F1, and the anode of the transient voltage suppressor D1 is grounded;

[0040] The switch module 100 has a control end coupled to the other end of the fuse F1, an input end coupled to the voltage input end VIN, and an output end coupled to a voltage output end VOUT. The switch module 100 is used to control the electrical connection between the voltage input end VIN and the voltage output end VOUT.

[0041] It should be noted that the fuse F1 is preferably a resettable fuse and a suitable fuse should be selected according to the actual application. hold Parameters are generally 10μA-0.5mA level. The fuse F1 is used in the circuit to cut off the connection between the voltage input terminal VIN and the transient voltage suppression tube D1 when overvoltage occurs.

[0042] It should also be noted that for the transient voltage suppressor D1, the operating voltage V RWM It should be slightly larger than the voltage of the protected signal. For example, the operating voltage V RWMis 1.1 to 1.2 times of VOUT, and the operating voltage V RWM and reverse breakdown voltage V BR The reverse breakdown voltage does not exceed the maximum operating voltage of VOUT. The transient voltage suppressor D1 is used to generate an overvoltage control signal at the cathode of the transient voltage suppressor D1 when the voltage input at the voltage input terminal VIN exceeds a threshold. The overvoltage control signal is used to control the circuit connection between the voltage input terminal VIN and the voltage output terminal VOUT of the switch module 100.

[0043] The overvoltage protection circuit provided in the present application adds a switch module in front of the voltage output terminal of the overvoltage protection circuit and adds a fuse between the transient voltage suppression tube and the voltage input terminal of the overvoltage protection circuit. When faced with continuous overvoltage or a semi-failure state of the transient voltage suppression tube, the fuse can be blown to cut off the connection between the transient voltage suppression tube and the voltage input terminal, thereby preventing the transient voltage suppression tube from continuing to heat up during overvoltage and avoiding safety accidents. At the same time, the switch module is used to cut off the connection between the voltage input terminal and the voltage output terminal, protecting the subsequent circuit from the influence of overvoltage.

[0044] In a possible implementation, the switch module 100 includes:

[0045] a first switch Q1 , wherein a control end of the first switch Q1 is coupled to the other end of the fuse F1 , and an output end of the first switch Q1 is grounded;

[0046] a first resistor R1, wherein one end of the first resistor R1 is coupled to the voltage input terminal VIN, and the other end of the first resistor R1 is coupled to the input terminal of the first switch Q1;

[0047] The second switch Q2 has a control terminal coupled to the input terminal of the first switch Q1 , an input terminal coupled to the voltage input terminal VIN, and an output terminal coupled to the voltage output terminal VOUT.

[0048] It should be noted that the function of the switch module 100 is to cut off the connection between the voltage input terminal VIN and the voltage output terminal VOUT when the input voltage of the voltage input terminal VIN exceeds a certain threshold.

[0049] For example, the first switch Q1 can be an NPN transistor, and the second switch Q2 can be a PMOS transistor. The first resistor R1 acts as a pull-up resistor for the collector of the first switch Q1, causing the collector of the first switch Q1 to output a voltage equivalent to the voltage input terminal VIN or 0V. Because the collector of the first switch Q1 is connected to the control terminal of the second switch Q2, the voltage at the collector of the first switch Q1 is consistent with the voltage at the control terminal of the second switch Q2.

[0050] The following uses an example in which the first switch Q1 is an NPN transistor and the second switch Q2 is a PMOS transistor to explain the working principle of the overvoltage circuit provided in the present application.

[0051] According to different voltage input states of the voltage input terminal VIN, it is divided into the following situations.

[0052] In the first case, when the voltage inputted at the voltage input terminal VIN is the normal input voltage, there is no overvoltage. For example, assuming that the voltage inputted at the voltage input terminal VIN is 5V, the transient voltage suppressor D1 generally selects the working voltage V RWM It is a 5.5V transient voltage suppressor, but it cannot exceed the maximum operating voltage of the protected circuit, that is, it cannot exceed the voltage of the voltage output terminal VOUT; at this time, because the input 5V≤V RWM , the breakdown condition of the transient voltage suppressor D1 is not exceeded. Current flows from fuse F1 to the transient voltage suppressor D1 (the leakage current is very small, typically a few μA) and the control terminal of the first switch Q1. It should be noted that the current flowing through fuse F1 is very small, so fuse F1 does not melt. Current flows to the control terminal of the first switch Q1, turning on the first switch Q1. Since the first switch Q1 is on, the second switch Q2 is also on, so there is conduction between the voltage input terminal VIN and the voltage output terminal VOUT.

[0053] For example, if the first switch Q1 is an NPN transistor and the second switch Q2 is a PMOS transistor, when fuse F1 is not blown, current will flow to the base of the NPN transistor, causing the transistor to enter the amplification region and the collector and emitter to conduct. Since the emitter is grounded, the collector voltage is 0V at this time. Since the gate of the PMOS transistor is coupled to the collector of the NPN transistor, the gate voltage of the PMOS transistor is also 0V at this time. The source of the PMOS transistor is connected to the voltage input terminal VIN, so the source voltage is 5V. VGS is equal to -5V, which is less than Vth (typically -2.5V). Therefore, the PMOS transistor is turned on, and the voltage output terminal VOUT normally outputs a voltage of 5V.

[0054] In the second case, if the voltage output terminal VOUT is required to output a voltage of 5V, the operating voltage V RWM 5.5V, breakdown voltage V BR The transient voltage suppressor D1 is 5.5V, and F1 is a 100μA fuse (greater than the leakage current of D1 and less than the reverse breakdown current). When the voltage input terminal VIN inputs a voltage of 6V, the input voltage exceeds the breakdown voltage V of the transient voltage suppressor D1. BR, the transient voltage suppressor D1 will conduct in the reverse direction, the current flowing through the fuse F1 will increase, the fuse F1 will melt, and the connection between the transient voltage suppressor D1 and the voltage input terminal VIN will be cut off. No large current will continue to pass through the transient voltage suppressor D1, so there will be no problem of the transient voltage suppressor D1 overheating or even burning surrounding components. At the same time, since the first switch is not conducting, the second switch is also not conducting, that is, there is no conduction between the voltage input terminal VIN and the voltage output terminal VOUT. In this way, the safety of the subsequent circuit connected to the voltage output terminal VOUT can be protected and no overvoltage problem will occur.

[0055] For example, in the case where the first switch Q1 is an NPN transistor and the second switch Q2 is a PMOS transistor, when the fuse F1 is blown, the base of the NPN transistor is at a low level, the NPN transistor is in a cut-off state, and is not conducting. At this time, the source and gate voltages of the PMOS transistor are equal, so the PMOS transistor is also not conducting, and no voltage is output at the voltage output terminal VOUT.

[0056] In a possible implementation, the overvoltage protection circuit further includes an input-end rectification and filtering module 200 , wherein the input end of the input-end rectification and filtering module 200 is coupled to the voltage input end VIN, and the output end of the input-end rectification and filtering module 200 is grounded.

[0057] In a possible implementation, the input-end rectification and filtering module 200 includes: at least one input-end capacitor, one end of the input-end capacitor is coupled to the voltage input end, and the other end is grounded.

[0058] For example, Figure 2 As shown, the input-end rectification and filtering module 200 includes three input-end capacitors, a first input-end capacitor C1 , a second input-end capacitor C2 , and a third input-end capacitor C3 .

[0059] In a possible implementation, the overvoltage protection circuit further includes: an output-end rectification and filtering module 300 , wherein the input end of the output-end rectification and filtering module is coupled to the output end of the switch module, and the output end is grounded.

[0060] In a possible implementation, the output-end rectification and filtering module 300 includes: at least one output-end capacitor, one end of the output-end capacitor is coupled to the voltage input end, and the other end is grounded.

[0061] For example, Figure 2 As shown, the output-end rectification and filtering module 300 includes two output-end capacitors, a first output-end capacitor C4 and a second output-end capacitor C5.

[0062] In a possible implementation, the overvoltage protection circuit further includes: a second resistor R2 , one end of the second resistor being coupled to the output end of the overvoltage signal output module, and the other end of the second resistor being coupled to the first input end of the switch module.

[0063] It should be noted that since the first switch Q1 is directly connected to the voltage input terminal VIN through the fuse F1, the current flowing to the control terminal of the first switch Q1 may be too large. In this case, a resistor needs to be added at the front end of the first switch Q1 to control the current flowing to the control terminal of the first switch Q1.

[0064] In a possible implementation, the overvoltage protection circuit further includes: a third resistor R3 , wherein the third resistor R3 is coupled between the output end of the switch module 100 and the voltage output end VOUT.

[0065] It should be noted that the role of the third resistor R3 in an actual product is to reduce circuit noise, ensure stable circuit operation, and better measure and monitor ground potential.

[0066] An embodiment of the present application also provides an overvoltage protection device, comprising any of the overvoltage protection circuits described above.

[0067] The overvoltage protection device provided in the present application adds a switch module in front of the voltage output terminal of the overvoltage protection circuit and adds a fuse between the transient voltage suppression tube and the voltage input terminal of the overvoltage protection circuit. When faced with continuous overvoltage or a semi-failure state of the transient voltage suppression tube, the fuse can be blown, cutting off the connection between the transient voltage suppression tube and the voltage input terminal, thereby preventing the transient voltage suppression tube from continuing to heat up during overvoltage and avoiding safety accidents. At the same time, the switch module is used to cut off the connection between the voltage input terminal and the voltage output terminal, protecting the subsequent circuit from the influence of overvoltage.

[0068] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0069] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0070] In the embodiments provided in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0071] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0072] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0073] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An overvoltage protection circuit, characterized in that: include: a fuse, one end of the fuse being coupled to a voltage input end; a transient voltage suppressor tube, wherein the cathode of the transient voltage suppressor tube is coupled to the other end of the fuse, and the anode of the transient voltage suppressor tube is grounded; A switch module, wherein the control end of the switch module is coupled to the other end of the fuse, the input end is coupled to the voltage input end, and the output end is coupled to a voltage output end. The switch module is used to control the electrical connection between the voltage input end and the voltage output end.

2. The overvoltage protection circuit according to claim 1, wherein: The switch module includes: a first switch, wherein a control end of the first switch is coupled to the other end of the fuse, and an output end of the first switch is grounded; a first resistor, wherein one end of the first resistor is coupled to the voltage input terminal, and the other end of the first resistor is coupled to the input terminal of the first switch; The second switch has a control terminal coupled to the input terminal of the first switch, an input terminal coupled to the voltage input terminal, and an output terminal coupled to the voltage output terminal.

3. The overvoltage protection circuit according to claim 2, wherein: The first switch is an NPN transistor, and the second switch is a PMOS transistor.

4. The overvoltage protection circuit according to claim 1, wherein: The overvoltage protection circuit further includes an input-end rectifying and filtering module, wherein the input end of the input-end rectifying and filtering module is coupled to the voltage input end, and the output end of the input-end rectifying and filtering module is grounded.

5. The overvoltage protection circuit according to claim 4, wherein: The input-end rectification and filtering module includes: at least one input-end filtering capacitor, one end of the input-end filtering capacitor is coupled to the voltage input end, and the other end is grounded.

6. The overvoltage protection circuit according to claim 1, wherein: The overvoltage protection circuit further includes: an output-end rectification and filtering module, wherein the input end of the output-end rectification and filtering module is coupled to the output end of the switch module, and the output end is grounded.

7. The overvoltage protection circuit according to claim 6, wherein: The output end rectification and filtering module includes: at least one output end filtering capacitor, one end of the output end filtering capacitor is coupled to the voltage input end, and the other end is grounded.

8. The overvoltage protection circuit according to claim 1, wherein: The overvoltage protection circuit further includes: a second resistor, one end of the second resistor is coupled to the output end of the overvoltage signal output module, and the other end of the second resistor is coupled to the first input end of the switch module.

9. The overvoltage protection circuit according to claim 1, wherein: The overvoltage protection circuit further includes: a third resistor coupled between the output terminal of the switch module and the voltage output terminal.

10. An overvoltage protection device, characterized in that: The overvoltage protection circuit comprises the overvoltage protection circuit according to any one of claims 1 to 9.

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