Anti-back-voltage circuit and electronic device

Abstract

The utility model discloses an anti-back-voltage circuit and an electronic device. The anti-back-voltage circuit comprises a power supply input end which is used for being connected with a direct-current power supply; the voltage reduction topology circuit is connected to the power supply input end; the output end is connected with the step-down topological circuit, and the output end is used for being connected with a load and outputting working voltage which is obtained through conversion of the step-down topological circuit and corresponds to the load; and the clamping unit is connected between the step-down topology circuit and the output end and is used for providing clamping protection when the output end outputs the working voltage so as to prevent or limit the output end from generating back voltage. According to the embodiment of the invention, the problem of back voltage of the output port in the buck conversion circuit can be improved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a circuit and an electronic device for preventing reverse voltage. Background Art

[0002] With the continuous development of communication technology, data center power supply system and integrated circuit chip technology, in electronic devices using DC sources, voltage converters are needed to convert the voltage of the power supply into the required working voltage. Buck circuit (step-down circuit) is a widely used step-down conversion circuit, which is mainly used for DC to DC (DC-DC) step-down conversion and is usually suitable for low-voltage and high-current applications.

[0003] In the process of using the above conversion circuit, when charging and discharging with large current, the current on the output power line changes rapidly when the hard shutdown protection is caused by an alarm or a fault, which will cause the output power line equivalent inductance and the output capacitor to resonate and produce excessive reverse voltage, resulting in damage to the output capacitor.

[0004] Therefore, for the buck converter circuit, the reverse voltage situation of the output port when the current stops needs to be solved or improved. Summary of the invention

[0005] The embodiments of the present application provide a circuit and an electronic device for preventing reverse voltage, which are used to solve and improve the problem of reverse voltage at the output port of a buck conversion circuit.

[0006] In a first aspect, the present application provides a reverse voltage protection circuit, the circuit comprising a power input terminal for connecting to a DC power supply;

[0007] A buck topology circuit, wherein the buck topology circuit is connected to the power input terminal;

[0008] An output end, the output end is connected to the buck topology circuit, the output end is used to connect a load and output a working voltage corresponding to the load obtained by conversion by the buck topology circuit;

[0009] A clamping unit is connected between the buck topology circuit and the output end, and is used to provide clamping protection when the output end outputs the working voltage, so as to prevent or limit the output end from generating a reverse voltage.

[0010] In some embodiments of the present application, the buck topology circuit includes:

[0011] A control switch connected to the first end of the power input end, the control switch is used to control the buck topology circuit to be turned on or off;

[0012] an inductor, wherein a first connection end of the inductor is connected to the control switch, a second connection end of the inductor is connected to the second end of the power input end, and the second connection end of the inductor is also connected to the output end, so as to realize conversion of the power supply voltage into the working voltage;

[0013] an output capacitor connected in parallel with the output terminal and in series with the inductor, the output capacitor being used for energy storage and voltage smoothing;

[0014] A freewheeling element is connected in parallel with the inductor and the output capacitor, and one end of the freewheeling element is connected to the control switch and the other end is connected to the second end of the power input terminal, so as to form a loop to neutralize or consume the reverse potential generated by the inductor.

[0015] In some embodiments of the present application, the control switch is a first NMOS transistor, the drain of the first NMOS transistor is connected to the positive electrode of the power input terminal, and the source is connected to the freewheeling element and the first connection terminal of the inductor.

[0016] In some embodiments of the present application, the freewheeling element is a second NMOS tube, the drain of the second NMOS tube is connected to the control switch and the first end of the inductor, and the source of the second NMOS tube is connected to the negative electrode of the power input terminal and the output capacitor.

[0017] In some embodiments of the present application, the freewheeling element is a freewheeling diode, and the freewheeling diode is reversely connected between the control switch and the second end of the power input end.

[0018] In some embodiments of the present application, one end of the output capacitor connected in series with the inductor is the first end of the output capacitor, and the other end is the second end of the output capacitor, the clamping unit is connected in parallel between the first end of the output capacitor and the second end of the output capacitor, and the clamping unit is turned on when the voltage at the second end of the output capacitor is greater than the voltage at the first end of the output capacitor.

[0019] In some embodiments of the present application, the clamping unit includes a Schottky diode, which is connected in parallel between the first end of the output capacitor and the second end of the output capacitor, and the Schottky diode is turned on when the voltage at the second end of the output capacitor is greater than the voltage at the first end of the output capacitor; the anode of the Schottky diode is connected to the cathode of the output end, and the cathode of the Schottky diode is connected to the anode of the output end.

[0020] In some embodiments of the present application, the forward voltage drop value of the clamping voltage of the clamping unit ranges from 0.3V to 0.7V.

[0021] In some embodiments of the present application, the load is a battery.

[0022] On the other hand, the present application provides an electronic device, comprising any reverse voltage protection circuit in the first aspect.

[0023] The present application implements a circuit and an electronic device that provide anti-reverse voltage. The power input terminal is connected to a DC power supply, and the output terminal is connected to a load. Corresponding to the working voltage required by the load, the buck topology circuit converts the power supply voltage into the working voltage. Since a clamping unit is provided, clamping protection can be provided for the output working voltage of the output terminal. When the current stops unexpectedly, reverse voltage can be prevented or limited from being generated at the output terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 is a connection diagram of a reverse pressure protection circuit provided in an embodiment of the present application;

[0026] Figure 2 It is a schematic diagram of the structure of the electronic device provided in an embodiment of the present application.

[0027] DC, direct current power supply; Q1, first NMOS transistor; Q2, second NMOS transistor; L, inductor; C1, output capacitor; BAT1, battery; D1, Schottky diode. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. 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 embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0030] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0033] For details, please refer to Figure 1 An embodiment of the present application provides a reverse voltage protection circuit, which includes a power supply input terminal, a buck topology circuit, an output terminal, and a clamping unit.

[0034] Among them, the power input end is used to connect to the DC power supply DC; the buck topology circuit is connected to the power input end; the output end is connected to the buck topology circuit, the output end is used to connect to the load, and output the working voltage corresponding to the load obtained by the buck topology circuit; the clamping unit is connected between the buck topology circuit and the output end, and is used to provide clamping protection when the output end outputs the working voltage, so as to prevent or limit the generation of reverse voltage at the output end.

[0035] The present application implements a circuit that provides anti-reverse voltage. By connecting the power input end to a DC power supply and the output end to a load, the buck topology circuit converts the power supply voltage into an operating voltage corresponding to the operating voltage required by the load, and a clamping unit is provided to provide clamping protection for the output operating voltage of the output end. When the current stops unexpectedly, the output end can be prevented or limited from generating reverse voltage.

[0036] In some embodiments, the load connected to the output terminal is a battery BAT1 , and the voltage output by the output terminal corresponds to the working voltage of the battery BAT1 .

[0037] In some embodiments, the buck topology circuit includes a control switch, an inductor L, an output capacitor C1, and a freewheeling element, which are described below:

[0038] like Figure 1 As shown, the control switch is connected to the first end of the power input terminal, and the control switch is used to control the buck topology circuit to be turned on or off; in a specific embodiment, the first end of the power input terminal is the positive end, and the control switch can be a first NMOS transistor Q1, the drain of the first NMOS transistor Q1 is connected to the positive electrode of the power input terminal, and the source is connected to the freewheeling element and the first connection end of the inductor L; the gate of the first NMOS transistor Q1 is connected to the control terminal to drive the control switch to be closed or opened.

[0039] An inductor L, a first connection end of the inductor L is connected to the control switch, a second connection end of the inductor L is connected to the second end of the power input end, and the second connection end of the inductor L is also connected to the output end to realize conversion of the power supply voltage into the working voltage.

[0040] The output capacitor C1 is connected in parallel with the output terminal and in series with the inductor L. The output capacitor C1 is used for energy storage and voltage smoothing. The capacitance of the output capacitor C1 corresponds to the required output working voltage.

[0041] A freewheeling element is connected in parallel with the inductor L and the output capacitor C1, and one end of the freewheeling element is connected to the control switch and the other end is connected to the second end of the power input end.

[0042] It should be noted that at the moment the control switch is disconnected, since the current in the inductor L cannot change suddenly, a reverse electromotive force with negative polarity at the top and positive polarity at the bottom will be generated. The freewheeling element can be used to form a loop to neutralize or consume the reverse potential generated by the inductor L.

[0043] In some embodiments, the freewheeling element is a second NMOS tube, the drain of the second NMOS tube is connected to the control switch and the first end of the inductor L, the source of the second NMOS tube is connected to the negative electrode of the power input terminal and the output capacitor C1, and the gate of the second NMOS transistor Q2 is connected to the control terminal.

[0044] In some other embodiments, the freewheeling element may also be a freewheeling diode, which is reversely connected between the control switch and the second end of the power input terminal.

[0045] It should also be noted that the reverse pressure generated at the output end in the present application is usually caused by the output power line being too long, resulting in an equivalent inductance L on the output power line, and the reverse pressure generated by resonance with the output capacitor C1. Therefore, the clamping unit is arranged between the output capacitor C1 and the output end to provide clamping protection when the output end outputs the working voltage. When the large current charging and discharging causes a hard shutdown protection due to an alarm or a fault, the reverse pressure generated at the output capacitor C1 can be suppressed.

[0046] In some embodiments, one end of the output capacitor C1 connected in series with the inductor L is the first end of the output capacitor C1, and the other end is the second end of the output capacitor C1. The clamping unit is connected in parallel between the first end of the output capacitor C1 and the second end of the output capacitor C1, and the clamping unit is turned on when the voltage at the second end of the output capacitor C1 is greater than the voltage at the first end of the output capacitor C1.

[0047] The clamping unit includes a Schottky diode D1, which is anti-parallel connected to both ends of the output capacitor C1, and is connected in parallel between the first end of the output capacitor C1 and the second end of the output capacitor C1, and the Schottky diode D1 is turned on when the voltage at the second end of the output capacitor C1 is greater than the voltage at the first end of the output capacitor C1; the anode of the Schottky diode D1 is connected to the cathode of the output end, and the cathode of the Schottky diode D1 is connected to the anode of the output end; that is, for the output capacitor C1, when it is turned on, the first end of the output capacitor C1 is the anode and the second end is the cathode, and by anti-parallel connecting the Schottky diode D1 between the first end of the output capacitor C1 and the second end of the output capacitor C1, when reverse voltage occurs, the voltage across the output capacitor C1 is limited to within the forward conduction voltage drop of the Schottky diode D1.

[0048] Since the Schottky diode D1 has low impedance, small forward voltage drop and fast recovery speed, it can prevent the output port from having too high reverse voltage. The reverse voltage range is within the diode voltage drop range, which also ensures that the output capacitor C1 will not be damaged due to excessive reverse voltage when hard shutdown protection is caused by an alarm or fault during high current charging and discharging. In addition, the Schottky diode D1 has a low cost, which saves component use while reducing costs.

[0049] In some embodiments, the forward voltage drop value of the clamping voltage of the clamping unit may be in the range of 0.3V-0.7V. Of course, the forward voltage drop value of the clamping voltage may also be selected to be in other ranges according to the connected load and the output capacitor C1.

[0050] On the other hand, the present application also provides an electronic device, such as Figure 2 As shown, the electronic device includes the anti-reverse voltage circuit in any of the above embodiments. In a specific example, the electronic device may include a power input terminal 601, a DC-DC buck converter 602, a clamping unit 603, and an output terminal 604. The buck topology circuit may be integrated or arranged in the DC-DC buck converter 602. The power input terminal 601, the clamping unit 603, and the output terminal 604 for connecting the load are respectively electrically connected to the DC-DC buck converter.

[0051] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0052] The above is a detailed introduction to an electronic device provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A circuit for preventing reverse pressure, characterized in that: include: Power input terminal, used to connect to a DC power supply; A buck topology circuit, wherein the buck topology circuit is connected to the power input terminal; An output end, the output end is connected to the buck topology circuit, the output end is used to connect a load and output a working voltage corresponding to the load obtained by conversion by the buck topology circuit; A clamping unit is connected between the buck topology circuit and the output end, and is used to provide clamping protection when the output end outputs the working voltage, so as to prevent or limit the output end from generating a reverse voltage.

2. The reverse voltage protection circuit according to claim 1, characterized in that: The buck topology circuit comprises: A control switch connected to the first end of the power input end, the control switch is used to control the buck topology circuit to be turned on or off; an inductor, wherein a first connection end of the inductor is connected to the control switch, a second connection end of the inductor is connected to the second end of the power input end, and the second connection end of the inductor is also connected to the output end, so as to realize conversion of the power supply voltage into the working voltage; an output capacitor connected in parallel with the output terminal and in series with the inductor, the output capacitor being used for energy storage and voltage smoothing; A freewheeling element is connected in parallel with the inductor and the output capacitor, and one end of the freewheeling element is connected to the control switch and the other end is connected to the second end of the power input terminal, so as to form a loop to neutralize or consume the reverse potential generated by the inductor.

3. The reverse voltage protection circuit according to claim 2, characterized in that: The control switch is a first NMOS transistor, a drain of the first NMOS transistor is connected to the positive electrode of the power input terminal, and a source of the first NMOS transistor is connected to the freewheeling element and the first connection terminal of the inductor.

4. The circuit for preventing reverse voltage as claimed in claim 2, characterized in that: The freewheeling element is a second NMOS tube, the drain of the second NMOS tube is connected to the control switch and the first end of the inductor, and the source of the second NMOS tube is connected to the negative electrode of the power input terminal and the output capacitor.

5. The reverse voltage protection circuit according to claim 2, characterized in that: The freewheeling element is a freewheeling diode, and the freewheeling diode is reversely connected between the control switch and the second end of the power input end.

6. The reverse voltage protection circuit according to claim 2, characterized in that: One end of the output capacitor connected in series with the inductor is the first end of the output capacitor, and the other end is the second end of the output capacitor. The clamping unit is connected in parallel between the first end of the output capacitor and the second end of the output capacitor, and the clamping unit is turned on when the voltage at the second end of the output capacitor is greater than the voltage at the first end of the output capacitor.

7. The circuit for preventing reverse voltage as claimed in claim 6, characterized in that: The clamping unit includes a Schottky diode, which is connected in parallel between the first end of the output capacitor and the second end of the output capacitor, and the Schottky diode is turned on when the voltage at the second end of the output capacitor is greater than the voltage at the first end of the output capacitor; the anode of the Schottky diode is connected to the cathode of the output end, and the cathode of the Schottky diode is connected to the anode of the output end.

8. The reverse voltage protection circuit according to claim 7, characterized in that: The forward voltage drop value of the clamping voltage of the clamping unit ranges from 0.3V to 0.7V.

9. The reverse voltage protection circuit according to any one of claims 1 to 8, characterized in that: The load is a battery.

10. An electronic device, characterized in that: A circuit for preventing reverse voltage according to any one of claims 1 to 9.

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