Power switching circuit and device

Abstract

The invention discloses a power supply switching circuit and device, and belongs to the field of power supplies, and the power supply switching circuit comprises a main power supply end, a backup power supply end, a circuit output end, a main power supply circuit, a switching circuit, a switching circuit and a power supply conversion circuit. The input end of the main power supply circuit is connected with the main power supply end, and the output end is connected with the circuit output end; the input end of the switching circuit is connected with the backup power supply end, and the output end is connected with the circuit output end; the input end of the power supply conversion circuit is connected with the main power supply end, the output end is connected with the switching circuit, and the power supply conversion circuit is used for converting the power supply change of the main power supply end into a level change control signal; the switching circuit is further connected with the backup power supply end and the switching circuit, and the switching circuit is used for controlling the switching circuit to be switched on according to the control signal so as to switch power supply of the circuit output end to the backup power supply from the main power supply. The invention aims to reduce the gate-source voltage withstanding requirement of the MOS tube in the circuit and reduce the circuit cost.

Description

Technical Field

[0001] The present invention relates to the field of power supplies, and in particular to a power supply switching circuit and device. Background Art

[0002] In electronic equipment, there is a design that uses the mains as the main power supply during normal operation and the battery as the backup power supply after the mains fails. The current power switching circuit solution generally controls the switching through diodes and MOS tubes. Figure 2 , the main power supply end is directly connected to the gate of the MOS tube. However, when the main power fails, the drop process of the main power output voltage is not completed immediately. The higher the voltage of the battery in the circuit, the greater the voltage between the gate and source of the MOS tube during the drop of the main power output voltage, which may eventually cause the breakdown of the MOS tube at a certain moment. Therefore, the current power switching circuit solution has high requirements on the gate-source withstand voltage of the MOS tube, which affects the circuit cost. Summary of the invention

[0003] The present invention provides a power switching circuit to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0004] The power switching circuit comprises: a main power supply end, a backup power supply end, a circuit output end, a main power circuit, a switch circuit, a switching circuit and a power supply conversion circuit; The main power supply end is used to connect to an external main power supply, and the backup power supply end is used to connect to an external backup power supply; The input end of the main power circuit is connected to the main power supply end, and the output end of the main power circuit is connected to the circuit output end; The input end of the switch circuit is connected to the backup power supply end, and the output end of the switch circuit is connected to the circuit output end; The input end of the power supply conversion circuit is connected to the main power supply end, the output end of the power supply conversion circuit is connected to the switching circuit, and the power supply conversion circuit is used to convert the power supply change of the main power supply end into a control signal with a level change; The switching circuit is also connected to the backup power supply end and the switch circuit respectively, and the switching circuit is used to control the switching circuit to be turned on according to the control signal to switch the power supply of the circuit output end from the main power supply to the backup power supply.

[0005] Optionally, the power supply conversion circuit includes: a first voltage regulator, a first resistor, a second resistor and a first transistor; The cathode of the first voltage regulator tube is connected to the main power supply terminal, and the anode of the first voltage regulator tube is connected to one end of the first resistor; The other end of the first resistor is respectively connected to one end of the second resistor and the base of the first transistor, the collector of the first transistor is connected to the switching circuit as the output end of the power supply conversion circuit, and the other end of the second resistor and the emitter of the first transistor are both grounded.

[0006] Optionally, the switching circuit includes a third resistor and a second transistor; One end of the third resistor is connected to the backup power supply end, and the other end of the third resistor is connected to the base of the second transistor; The base of the second transistor is connected to the output end of the power supply conversion circuit, the collector of the second transistor is connected to the switch circuit, and the emitter of the second transistor is grounded.

[0007] Optionally, the power switching circuit further includes a fourth resistor, and the switch circuit includes a first MOS transistor and a second MOS transistor; The drain of the first MOS tube is connected to the backup power supply end as the input end of the switch circuit, the source of the first MOS tube is connected to the source of the second MOS tube, the drain of the second MOS tube is connected to the output end of the circuit as the output end of the switch circuit, the gate of the first MOS tube is connected to the gate of the second MOS tube, the gate of the first MOS tube is connected to one end of the fourth resistor as the control end of the switch circuit, and the other end of the fourth resistor is connected to the switching circuit.

[0008] Optionally, the switch circuit further includes a second voltage regulator tube; The cathode of the second voltage regulator tube is connected to the source of the first MOS tube and the source of the second MOS tube respectively, and the anode of the second voltage regulator tube is connected to the gate of the first MOS tube and the gate of the second MOS tube respectively.

[0009] Optionally, the switch circuit further includes a capacitor; One end of the capacitor is connected to the source of the first MOS tube and the source of the second MOS tube respectively, and the other end of the capacitor is connected to the gate of the first MOS tube and the gate of the second MOS tube respectively.

[0010] Optionally, the switch circuit further includes a fifth resistor; One end of the fifth resistor is connected to the source of the first MOS transistor and the source of the second MOS transistor respectively, and the other end of the fifth resistor is connected to the gate of the first MOS transistor and the gate of the second MOS transistor respectively.

[0011] Optionally, the main power circuit includes a diode; The anode of the diode is connected to the main power supply end as the input end of the main power circuit, and the cathode of the diode is connected to the circuit output end as the output end of the main power circuit.

[0012] Optionally, the output voltage of the main power supply end is greater than the output voltage of the backup power supply end.

[0013] In addition, a power switching circuit device is also provided, wherein the power switching circuit device comprises the power switching circuit as described in any one of the above items.

[0014] The present invention has at least the following beneficial effects: when the main power supply is normally powered, the current is output to the circuit output end through the main power circuit connected to the main power supply end, and at the same time, the main power supply end is also connected to the power supply conversion circuit. When the main power supply is powered off, even if the voltage at the main power supply end drops, the power supply conversion circuit converts the voltage drop process into a jump level change to form a corresponding control signal, and then controls the switching to the backup power supply end based on the control signal through the switching circuit and the switch circuit. Compared with the main power supply being directly connected to the gate of the MOS tube, the power supply conversion circuit converts the gradually decreasing main power output voltage into a jump control signal, thereby avoiding the breakdown of the MOS tube inside the switch circuit during the voltage drop process, reducing the gate-source withstand voltage requirements of the MOS tube, and reducing the circuit cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0016] Figure 1 It is a schematic diagram of the framework of the power switching circuit of the present invention; Figure 2 It is a circuit schematic diagram of a power switching circuit in the prior art; Figure 3 FIG. 4 is a circuit diagram of an embodiment of a power switching circuit of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] It should be noted that, although the functional modules are divided in the system schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the system or the order in the flowchart. The terms "first", "second", etc. in the specification, claims and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0019] The embodiment of the present invention provides a power switching circuit. Figure 1 In this embodiment, the power switching circuit includes: a main power supply end, a backup power supply end, a circuit output end, a main power circuit 100, a switch circuit 200, a switching circuit 400 and a power conversion circuit 300.

[0020] The main power supply terminal is used to connect to an external main power supply, and the backup power supply terminal is used to connect to an external backup power supply.

[0021] The input end of the main power circuit is connected to the main power supply end, and the output end of the main power circuit is connected to the circuit output end.

[0022] The input end of the switch circuit 200 is connected to the backup power supply end, and the output end of the switch circuit 200 is connected to the circuit output end.

[0023] The input end of the power conversion circuit 300 is connected to the main power supply end, and the output end of the power conversion circuit 300 is connected to the switching circuit 400. The power conversion circuit 300 is used to convert the power supply change of the main power supply end into a control signal with a level change.

[0024] The switching circuit 400 is also connected to the backup power supply end and the switch circuit 200 respectively. The switching circuit 400 is used to control the switch circuit 200 to conduct according to the control signal to switch the power supply of the circuit output end from the main power supply to the backup power supply.

[0025] It should be noted that in the drawings, Vcc is used to indicate the main power supply terminal. In this embodiment, the backup power supply is a battery, and BAT is used to indicate the backup power supply terminal. In other embodiments, the backup power supply may also be other types of power supplies other than batteries. In addition, OUT is used to indicate the circuit output terminal. Figure 2 In the prior art shown, the main power supply terminal is directly connected to the gate of the third MOS tube Q5. Therefore, when the main power fails, the gate-source voltage of the third MOS tube Q5 is too large, resulting in breakdown and damage to the third MOS tube Q5.

[0026] The electric energy provided by the main power supply end is formed by the external mains power after AC to DC conversion and other processing steps. The electric energy provided by the backup power supply end is formed by the discharge of the external backup power supply. When the mains power is normal and the main power supply is normally supplied, the current output by the main power supply end flows into the main power supply circuit 100 and the power supply conversion circuit 300. When the main power supply loses power, the output voltage of the main power supply end drops to zero. The power supply changes of the main power supply end in two states are converted into level changes through the power supply conversion circuit 300. The level change forms a corresponding control signal. When the main power supply is normally supplied, the switching circuit 400 controls the switch circuit 200 to disconnect according to the control signal at this time, so that only the main power supply end provides electric energy to the circuit output end. When the main power supply loses power, the switching circuit 400 controls the switch circuit 200 to turn on according to the control signal at this time, and switches to the backup power supply end providing electric energy to the circuit output end.

[0027] A power switching circuit proposed in an embodiment of the present invention, when the main power supply is normally powered, the current is output to the circuit output end through the main power circuit 100 connected to the main power supply end, and at the same time, the main power supply end is also connected to the power conversion circuit 300. When the main power supply loses power, even if the voltage at the main power supply end drops, the power conversion circuit 300 converts the voltage drop process into a jump level change to form a corresponding control signal, and then controls the switching to the backup power supply end based on the control signal through the switching circuit 400 and the switch circuit 200. Compared with the main power supply directly connected to the gate of the MOS tube, the power conversion circuit 300 realizes the conversion of the gradually decreasing main power output voltage into a jump control signal, avoids the breakdown of the MOS tube inside the switch circuit 200 during the voltage drop process, reduces the gate-source withstand voltage requirements of the MOS tube, and reduces the circuit cost.

[0028] Further, in this embodiment, referring to Figure 3 The power supply conversion circuit 300 includes a first voltage regulator tube D1, a first resistor R1, a second resistor R2 and a first transistor Q1.

[0029] The cathode of the first voltage regulator tube D1 is connected to the main power supply terminal, and the anode of the first voltage regulator tube D1 is connected to one end of the first resistor R1.

[0030] The other end of the first resistor R1 is connected to one end of the second resistor R2 and the base of the first transistor Q1 respectively. The collector of the first transistor Q1 is connected to the switching circuit 400 as the output end of the power supply conversion circuit 300. The other end of the second resistor R2 and the emitter of the first transistor Q1 are both grounded.

[0031] When the main power supply is supplying power normally, the output voltage of the main power supply end reversely breaks down the first voltage regulator D1, causing the first voltage regulator D1 to output a regulated voltage, and the first transistor Q1 is turned on by applying the regulated voltage to the base of the first transistor Q1; and when the main power supply is lost and the output voltage of the main power supply end is not sufficient to reversely break down the first voltage regulator D1, the output voltage of the first voltage regulator D1 jumps to zero, and there is no regulated voltage at the base of the first transistor Q1, causing the first transistor Q1 to not conduct, and a control signal for the switching circuit 400 is formed through the conduction state of the first transistor Q1.

[0032] Through the cooperation of the first voltage regulator D1 and the first transistor Q1, the influence of the gradual decrease in the output voltage at the power supply end when the main power supply is lost is isolated, and converted into a control signal for the switching circuit 400, thereby avoiding the breakdown of the MOS tube inside the switching circuit 200 during the voltage drop process, reducing the gate-source withstand voltage requirement of the MOS tube, and reducing the circuit cost.

[0033] Further, in this embodiment, referring to Figure 3 , the switching circuit 400 includes a third resistor R3 and a second transistor Q2.

[0034] One end of the third resistor R3 is connected to the backup power supply end, and the other end of the third resistor R3 is connected to the base of the second transistor Q2.

[0035] The base of the second transistor Q2 is connected to the output end of the power supply conversion circuit 300 , the collector of the second transistor Q2 is connected to the switch circuit 200 , and the emitter of the second transistor Q2 is grounded.

[0036] When the main power supply is normally supplied and the first transistor Q1 in the power supply conversion circuit 300 is turned on, the base of the second transistor Q2 is grounded through the first transistor Q1, causing the second transistor Q2 to be non-conductive; and when the main power supply is lost and the first transistor Q1 is non-conductive, the base of the second transistor Q2 is connected to the backup power supply end through the third resistor R3, and based on the output voltage of the backup power supply end, the second transistor Q2 is turned on, and the collector of the second transistor Q2 is connected to the switch circuit 200, and the switch circuit 200 is controlled by the conduction state of the second transistor Q2.

[0037] By making the second transistor Q2 control the conduction of the switch circuit 200 according to the conduction state of the first transistor Q1, while transmitting the control signal of the power supply conversion circuit 300, the influence of the main power supply end on the switch circuit 200 is further isolated, thereby realizing the function of power supply switching and improving circuit safety.

[0038] Further, in this embodiment, referring to Figure 3 , the main power supply circuit 100 includes a diode D2.

[0039] The anode of the diode D2 is connected to the main power supply end as the input end of the main power circuit 100 , and the cathode of the diode D2 is connected to the circuit output end as the output end of the main power circuit 100 .

[0040] When the main power supply is operating normally, diode D2 is turned on, so that the current output from the main power supply end is transmitted to the circuit output end; when the main power supply fails, diode D2 can reversely block the current output from the backup power supply end to the circuit output end from affecting the main power supply end. In addition, it can also prevent the current at the circuit output end from flowing back and affecting the main power supply end, thereby improving the safety and reliability of the circuit.

[0041] Furthermore, in this embodiment, the output voltage of the main power supply end is greater than the output voltage of the backup power supply end.

[0042] Optionally, the output voltage of the main power supply end is 24V, and the external battery includes a lead-acid battery and a lithium battery. In this embodiment, the output voltage of the backup power supply end is formed by the voltage of the lead-acid battery and the lithium battery, and is in the range of 12V to 16.8V. Therefore, the output voltage of the main power supply end is greater than the output voltage of the backup power supply end.

[0043] By making the output voltage of the main power supply end greater than the output voltage of the backup power supply end, the two power supply ends can be effectively distinguished, thereby improving the safety of the circuit.

[0044] Further, in this embodiment, referring to Figure 3 The power switching circuit further includes a fourth resistor R4, and the switch circuit 200 includes a first MOS transistor Q3 and a second MOS transistor Q4.

[0045] The drain of the first MOS transistor Q3 is connected to the backup power supply end as the input end of the switch circuit 200, the source of the first MOS transistor Q3 is connected to the source of the second MOS transistor Q4, the drain of the second MOS transistor Q4 is connected to the output end of the circuit as the output end of the switch circuit 200, the gate of the first MOS transistor Q3 is connected to the gate of the second MOS transistor Q4, the gate of the first MOS transistor Q3 is connected to one end of the fourth resistor R4 as the control end of the switch circuit 200, and the other end of the fourth resistor is connected to the switching circuit 400.

[0046] like Figure 3 As shown, the first MOS transistor Q3 and the second MOS transistor Q4 are both P-channel MOS transistors, and their body diodes D2 are directed from the drain to the source.

[0047] When the main power supply is normally supplied and the second triode Q2 is not turned on, no voltage for driving the first MOS tube Q3 and the second MOS tube Q4 to be turned on can be formed between the gate and source electrodes, so the first MOS tube Q3 and the second MOS tube Q4 are both turned off; when the main power supply is lost and the second triode Q2 is turned on, the gate electrodes of the first MOS tube Q3 and the second MOS tube Q4 are both grounded through the fourth resistor R4 and the second triode Q2, and then based on the voltage applied to the drain electrode of the first MOS tube Q3 and the source electrode of the second MOS tube Q4 by the backup power supply end, the first MOS tube Q3 and the second MOS tube Q4 are driven to be turned on, so that the current output by the backup power supply end can be transmitted to the circuit output end through the switch circuit 200, so that the backup power supply end provides electric energy.

[0048] In addition, by connecting two MOS tubes in series, when the two MOS tubes are not conducting, the body diode D2 in the opposite direction can prevent the current backflow at the output end of the circuit from affecting the backup power supply end, and can also effectively block the backup power supply end from supplying power to the output end of the circuit at this time, thereby improving the safety and reliability of the circuit.

[0049] Furthermore, in this embodiment, the switch circuit 200 also includes a second voltage regulator tube D3.

[0050] The cathode of the second voltage regulator tube D3 is connected to the source of the first MOS tube Q3 and the source of the second MOS tube Q4 respectively, and the anode of the second voltage regulator tube D3 is connected to the gate of the first MOS tube Q3 and the gate of the second MOS tube Q4 respectively.

[0051] By adding the second voltage regulator tube D3, the gate-source voltage of the first MOS tube Q3 and the second MOS tube Q4 can be effectively controlled, further preventing the problem of MOS tube breakdown due to excessive gate-source voltage, thereby improving the safety of the circuit.

[0052] Furthermore, in this embodiment, the switch circuit 200 further includes a capacitor C1.

[0053] One end of the capacitor C1 is connected to the source of the first MOS transistor Q3 and the source of the second MOS transistor Q4 respectively, and the other end of the capacitor C1 is connected to the gate of the first MOS transistor Q3 and the gate of the second MOS transistor Q4 respectively.

[0054] By adding the capacitor C1 and utilizing the characteristic that the voltage across the capacitor C1 cannot change suddenly, a slow start is achieved, so that the gate-source voltage of the first MOS transistor Q3 and the second MOS transistor Q4 rises slowly, and at the same time, the influence of surge current in the circuit is reduced, the first MOS transistor Q3 and the second MOS transistor Q4 are protected, and the safety of the circuit is improved.

[0055] Furthermore, in this embodiment, the switch circuit 200 further includes a fifth resistor R5.

[0056] One end of the fifth resistor R5 is connected to the source of the first MOS transistor Q3 and the source of the second MOS transistor Q4 respectively, and the other end of the fifth resistor R5 is connected to the gate of the first MOS transistor Q3 and the gate of the second MOS transistor Q4 respectively.

[0057] By further connecting the fifth resistor R5 in parallel to the capacitor C1, a load for consuming the stored electric energy of the capacitor C1 is provided. At the same time, in combination with the fourth resistor R4, the gate voltage of the first MOS transistor Q3 and the second MOS transistor Q4 is raised by voltage division, thereby reducing the voltage difference between the gate and the source of the first MOS transistor Q3 and the second MOS transistor Q4, protecting the first MOS transistor Q3 and the second MOS transistor Q4, and improving the safety of the circuit.

[0058] In addition, the present invention further provides a power switching circuit device, including the power switching circuit described in the above embodiment.

[0059] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0060] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0061] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, 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 an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0062] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0063] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0064] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Access Memory, referred to as RAM), disk or optical disk and other media that can store program codes.

[0065] Although the description of the present application has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims, taking into account the prior art, so as to effectively cover the intended scope of the present application. In addition, the above description of the present application is based on the embodiments foreseeable by the inventor, and its purpose is to provide a useful description, and those non-substantial changes to the present application that have not yet been foreseen may still represent equivalent changes to the present application.

Claims

1. A power switching circuit, characterized in that: The power switching circuit comprises: a main power supply end, a backup power supply end, a circuit output end, a main power circuit, a switch circuit, a switching circuit and a power supply conversion circuit; The main power supply end is used to connect to an external main power supply, and the backup power supply end is used to connect to an external backup power supply; The input end of the main power circuit is connected to the main power supply end, and the output end of the main power circuit is connected to the circuit output end; The input end of the switch circuit is connected to the backup power supply end, and the output end of the switch circuit is connected to the circuit output end; The input end of the power supply conversion circuit is connected to the main power supply end, the output end of the power supply conversion circuit is connected to the switching circuit, and the power supply conversion circuit is used to convert the power supply change of the main power supply end into a control signal with a level change; The switching circuit is also connected to the backup power supply end and the switch circuit respectively, and the switching circuit is used to control the switching circuit to be turned on according to the control signal to switch the power supply of the circuit output end from the main power supply to the backup power supply.

2. The power switching circuit according to claim 1, characterized in that: The power supply conversion circuit comprises: a first voltage regulator tube, a first resistor, a second resistor and a first triode; The cathode of the first voltage regulator tube is connected to the main power supply terminal, and the anode of the first voltage regulator tube is connected to one end of the first resistor; The other end of the first resistor is respectively connected to one end of the second resistor and the base of the first transistor, the collector of the first transistor is connected to the switching circuit as the output end of the power supply conversion circuit, and the other end of the second resistor and the emitter of the first transistor are both grounded.

3. The power switching circuit according to claim 1, characterized in that: The switching circuit includes a third resistor and a second triode; One end of the third resistor is connected to the backup power supply end, and the other end of the third resistor is connected to the base of the second transistor; The base of the second transistor is connected to the output end of the power supply conversion circuit, the collector of the second transistor is connected to the switch circuit, and the emitter of the second transistor is grounded.

4. The power switching circuit according to claim 1, characterized in that: The power switching circuit further includes a fourth resistor, and the switch circuit includes a first MOS transistor and a second MOS transistor; The drain of the first MOS tube is connected to the backup power supply end as the input end of the switch circuit, the source of the first MOS tube is connected to the source of the second MOS tube, the drain of the second MOS tube is connected to the output end of the circuit as the output end of the switch circuit, the gate of the first MOS tube is connected to the gate of the second MOS tube, the gate of the first MOS tube is connected to one end of the fourth resistor as the control end of the switch circuit, and the other end of the fourth resistor is connected to the switching circuit.

5. The power switching circuit according to claim 4, characterized in that: The switch circuit also includes a second voltage regulator tube; The cathode of the second voltage regulator tube is connected to the source of the first MOS tube and the source of the second MOS tube respectively, and the anode of the second voltage regulator tube is connected to the gate of the first MOS tube and the gate of the second MOS tube respectively.

6. The power switching circuit according to claim 5, characterized in that: The switch circuit also includes a capacitor; One end of the capacitor is connected to the source of the first MOS tube and the source of the second MOS tube respectively, and the other end of the capacitor is connected to the gate of the first MOS tube and the gate of the second MOS tube respectively.

7. The power switching circuit according to claim 6, characterized in that: The switch circuit further includes a fifth resistor; One end of the fifth resistor is connected to the source of the first MOS transistor and the source of the second MOS transistor respectively, and the other end of the fifth resistor is connected to the gate of the first MOS transistor and the gate of the second MOS transistor respectively.

8. The power switching circuit according to claim 1, characterized in that: The main power circuit includes a diode; The anode of the diode is connected to the main power supply end as the input end of the main power circuit, and the cathode of the diode is connected to the circuit output end as the output end of the main power circuit.

9. The power switching circuit according to claim 1, characterized in that: The output voltage of the main power supply end is greater than the output voltage of the backup power supply end.

10. A power switching circuit device, characterized in that: The power switching circuit device comprises the power switching circuit according to any one of claims 1 to 9.

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