Dual power supply anti-backflow circuit and system

Abstract

This application relates to a dual-power backflow prevention circuit and system. The dual-power backflow prevention circuit includes: a switching circuit and a control circuit. A first terminal of the switching circuit is connected to a first power source, and a second terminal of the switching circuit is connected to a second power source. A first terminal of the control circuit is connected to the first terminal of the switching circuit, a second terminal of the control circuit is connected to the second terminal of the switching circuit, and a third terminal of the control circuit is connected to the third terminal of the switching circuit. The control circuit is used to generate a first control signal when either the first or second power source is used as the power supply, and to generate a second control signal when both the first and second power sources are used as the power supply. The switching circuit is used to connect the power supply and the load according to the first control signal, and to disconnect the connection between the first and second power sources according to the second control signal. The dual-power backflow prevention circuit of this application can reduce the control resource usage.

Description

Technical Field

[0001] This application relates to the field of dual power supply control technology, and in particular to a dual power supply anti-backflow circuit and system. Background Technology

[0002] In the Netherlands, residents commonly use electricity meters based on DSMR (Dutch Smart Meter Requirements), which can exchange data or supply power via an RJ12 interface. Several versions of DSMR exist; some are powered by the meter itself, while others require an external power source. This dual power supply necessitates measures to prevent power backflow.

[0003] In traditional technology, a dual-power reverse current prevention circuit can be constructed by connecting two PMOS transistors back to back and using a switching transistor to drive the two PMOS transistors, so as to achieve circuit breaking when both power supplies are supplied at the same time, thereby preventing current reverse current.

[0004] However, traditional dual-power reverse-current protection circuits require separate detection of the voltage on both power supply sides and additional control of the switching transistor to turn on or off, resulting in high control resource consumption. Utility Model Content

[0005] Therefore, it is necessary to provide a dual-power anti-backflow circuit and system that can reduce the consumption of control resources.

[0006] In a first aspect, this application provides a dual-power reverse-current protection circuit, the circuit comprising:

[0007] The circuit includes a switching circuit and a control circuit. The first terminal of the switching circuit is connected to a first power source, and the second terminal of the switching circuit is connected to a second power source. The first terminal of the control circuit is connected to the first terminal of the switching circuit, the second terminal of the control circuit is connected to the second terminal of the switching circuit, and the third terminal of the control circuit is connected to the third terminal of the switching circuit.

[0008] A control circuit is used to generate a first control signal when either a first power supply or a second power supply is used as the power source, and to generate a second control signal when both the first power supply and the second power supply are used as the power source.

[0009] A switching circuit is used to connect the power supply and the load according to a first control signal, and to disconnect the connection between the first power supply and the second power supply according to a second control signal.

[0010] In one embodiment, the control circuit includes a voltage comparison circuit and a turn-on control circuit;

[0011] The first input terminal of the voltage comparator circuit is connected to the first terminal of the switching circuit, the second input terminal of the voltage comparator circuit is connected to the second terminal of the switching circuit, and the output terminal of the voltage comparator circuit is connected to the first and second terminals of the conduction control circuit, respectively.

[0012] The third terminal of the conduction control circuit is connected to the third terminal of the switching circuit;

[0013] A voltage comparison circuit is used to compare the voltage at the first terminal of the switching circuit with the voltage at the second terminal of the switching circuit and output a comparison voltage signal.

[0014] The conduction control circuit is used to generate a first control signal or a second control signal based on the comparison voltage signal.

[0015] In one embodiment, the voltage comparison circuit includes: a comparator U1, a Zener diode ZD1, resistors R8, R9, R10, and R11, and a capacitor C2.

[0016] The first input terminal of comparator U1 is connected to the first terminal of Zener diode ZD1, and is also connected to the first terminal of the switching circuit through resistor R10; the second input terminal of comparator U1 is connected to the second terminal of the switching circuit through resistor R8, and is grounded through resistor R9 and capacitor C2; the output terminal of comparator U1 is connected to the first terminal of the turn-on control circuit, and is also connected to the first terminal of resistor R11; the second terminal of resistor R11 is connected to the second terminal of the turn-on control circuit.

[0017] Comparator U1 is used to compare the first voltage at the first input terminal of comparator U1 with the second voltage at the second input terminal of comparator U1, and outputs a comparison voltage signal.

[0018] In one embodiment, the conduction control circuit includes: diode D2, diode D3, resistor R12, and resistor R13.

[0019] The cathode of diode D2 is connected to the second terminal of resistor R11 and to the first terminal of the switching circuit, and is also grounded through resistor R12;

[0020] The cathode of diode D3 is connected to the output of comparator U1 and is also grounded through resistor R13;

[0021] Diodes D2 and D3 are used to generate a first control signal or a second control signal based on a comparison voltage signal.

[0022] In one embodiment, the switching circuit includes a first switching circuit and a second switching circuit.

[0023] The first terminal of the first switching circuit is connected to the anode of diode D2 and the anode of diode D3, and the second terminal of the first switching circuit is connected to the first terminal of the second switching circuit.

[0024] The second terminal of the second switching circuit is connected to the first power supply, and the third terminal of the second switching circuit is connected to the second power supply.

[0025] The first switching circuit is used to generate a conduction control signal according to a first control signal and a cutoff control signal according to a second control signal.

[0026] The second switching circuit is used to turn on the power supply and load according to the turn-on control signal, and to disconnect the connection between the first power supply and the second power supply according to the cut-off control signal.

[0027] In one embodiment, the first switching circuit includes switching transistors Q3 and Q4, resistors R3, R4, R5, R6, and R7.

[0028] The gate of the switching transistor Q4 is connected to the positive terminals of diodes D2 and D3 respectively, and is connected to the second switching circuit through resistor R7. The source of the switching transistor Q4 is grounded, the drain of the switching transistor Q4 is connected to the gate of the switching transistor Q3, and is connected to the second power supply through resistor R5 and the first power supply through resistor R6.

[0029] The source of the switching transistor Q3 is grounded, and the drain of the switching transistor Q3 is connected to the first terminal of the resistor R4.

[0030] The second terminal of resistor R4 is connected to the first terminal of the second switching circuit, and is connected to the fourth terminal of the second switching circuit through resistor R3;

[0031] Switching transistors Q3 and Q4 are used to generate a turn-on control signal based on a first control signal and a cut-off control signal based on a second control signal.

[0032] In one embodiment, the second switching circuit includes: switching transistor Q1 and switching transistor Q2.

[0033] The drain of switch Q1 is connected to the first power supply, the source of switch Q1 is connected to the source of switch Q2, the drain of switch Q2 is connected to the second power supply, and the gates of switch Q1 and switch Q2 are both connected to the second terminal of resistor R4.

[0034] Switch Q1 and switch Q2 are used to turn on the power supply and load according to the turn-on control signal, and to disconnect the connection between the first power supply and the second power supply according to the cut-off control signal.

[0035] In one embodiment, the first switching circuit further includes a capacitor C1.

[0036] The first terminal of capacitor C1 is connected to the gate of switching transistor Q3, and the second terminal of capacitor C1 is grounded.

[0037] In one embodiment, the circuit may further include: a diode D1, the first end of which is connected to a first power supply, and the second end of which is connected to the first end of a switching circuit.

[0038] Secondly, this application provides a dual-power backflow prevention system, including a first power supply, a second power supply, and a dual-power backflow prevention circuit as described in the first aspect.

[0039] In the aforementioned dual-power backflow prevention circuit and system, when either the first or second power supply is powered from one side, the control circuit generates a first control signal based on the electrical signals from the first and second terminals of the switching circuit. The switching circuit then connects the power supply and the load according to the first control signal, enabling the single-sided power supply to power both the first and second loads. When both the first and second power supplies are powered, the control circuit generates a second control signal based on the electrical signals from the first and second terminals of the switching circuit. The switching circuit then disconnects the connection between the first and second power supplies according to the second control signal, preventing backflow and ensuring that the first power supply powers the first load and the second power supply powers the second load independently. Furthermore, the control circuit only needs to acquire the electrical signals from the first and second terminals of the switching circuit to generate the corresponding control signal, saving the use of the GPIO (General Purpose Input / Output) interface in the dual-power backflow prevention circuit and thus reducing control resource consumption. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is an example of a dual-power reverse-current protection circuit;

[0042] Figure 2 for Figure 1 A circuit structure for control circuits in China;

[0043] Figure 3 This is a circuit structure in one embodiment where the first power supply is powered from one side only;

[0044] Figure 4This is a circuit structure in one embodiment where the second power supply is powered from one side only;

[0045] Figure 5 This is a circuit structure in one embodiment where a first power supply and a second power supply are supplied from both sides.

[0046] Explanation of reference numerals in the attached figures:

[0047] 100. Dual power supply anti-backflow circuit; 110. Switching circuit; 111. First switching circuit; 112. Second switching circuit; 120. Control circuit; 121. Voltage comparison circuit; 122. Turn-on control circuit; 200. First power supply; 300. Second power supply. Detailed Implementation

[0048] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0050] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0051] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, units, etc., have electrical signal or data transmission with each other.

[0052] When used here, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “including / contains” or “having” specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0053] The dual-power backflow prevention circuit 100 provided in this embodiment can be applied to applications involving dual power supply, such as DSMR meters. The following description uses the application of the dual-power backflow prevention circuit 100 in a DSMR meter as an example. Switch S1 and the first power supply 200 simulate a power adapter, while switch S2 and the second power supply 300 simulate the meter. Closing S1 provides power from the first power supply 200, and closing S2 provides power from the second power supply 300. The load includes a first load and a second load. The first load is close to switch S1. Figures 3 to 5 R1 represents the power consumption of the product itself. The second load is close to switch S2. Figures 3 to 5 R2 is used to represent the power consumption of the analog meter.

[0054] In one exemplary embodiment, such as Figure 1 As shown, a dual-power backflow prevention circuit 100 is provided, which includes a switching circuit 110 and a control circuit 120.

[0055] The first terminal of the switching circuit 110 is used to connect to the first power supply 200, and the second terminal of the switching circuit 110 is used to connect to the second power supply 300; the first terminal of the control circuit 120 is connected to the first terminal of the switching circuit 110, the second terminal of the control circuit 120 is connected to the second terminal of the switching circuit 110, and the third terminal of the control circuit 120 is connected to the third terminal of the switching circuit 110.

[0056] The control circuit 120 is used to generate a first control signal when the first power supply 200 or the second power supply 300 is used as the power supply, and to generate a second control signal when the first power supply 200 and the second power supply 300 are used as the power supply; the switching circuit 110 is used to connect the power supply and the load according to the first control signal, and to disconnect the connection between the first power supply 200 and the second power supply 300 according to the second control signal.

[0057] In this embodiment, when either the first power supply 200 or the second power supply 300 is powered from one side, the control circuit 120 generates a first control signal based on the electrical signals from the first and second terminals of the switch circuit 110. The switch circuit 110 then connects the power supply and the load according to the first control signal, enabling the single-sided power supply to power the first and second loads. When both the first power supply 200 and the second power supply 300 are powered from both sides, the control circuit 120 generates a second control signal based on the electrical signals from the first and second terminals of the switch circuit 110. The switch circuit 110 then disconnects the connection between the first power supply 200 and the second power supply 300 according to the second control signal, preventing current backflow between the first power supply 200 and the second power supply 300. This allows the first power supply 200 to power the first load alone, and the second power supply 300 to power the second load alone. Furthermore, the control circuit 120 only needs to collect the electrical signals from the first and second terminals of the switch circuit 110 to generate the corresponding control signal, saving the GPIO interface usage of the dual-power backflow prevention circuit 100 and thus reducing control resource usage.

[0058] In one exemplary embodiment, such as Figure 2 As shown, the control circuit 120 includes a voltage comparison circuit 121 and a conduction control circuit 122.

[0059] The first input terminal of the voltage comparator circuit 121 is connected to the first terminal of the switching circuit, the second input terminal of the voltage comparator circuit 121 is connected to the second terminal of the switching circuit, and the output terminal of the voltage comparator circuit 121 is connected to the first and second terminals of the turn-on control circuit 122, respectively. The third terminal of the turn-on control circuit 122 is connected to the third terminal of the switching circuit. The voltage comparator circuit 121 is used to compare the voltage at the first terminal of the switching circuit with the voltage at the second terminal of the switching circuit and output a comparison voltage signal. The turn-on control circuit 122 is used to generate a first control signal or a second control signal based on the comparison voltage signal.

[0060] In this embodiment, the voltage comparison circuit 121 compares the voltage at the first terminal of the switching circuit 110 with the voltage at the second terminal of the switching circuit 110. The conduction control circuit 122 generates a first control signal or a second control signal based on the comparison voltage signal. The logic AND is implemented in pure hardware, which is not affected by software timing while achieving independent power supply and mutual isolation of the power supply, and has high reliability.

[0061] In one possible implementation, such as Figure 3As shown, the voltage comparison circuit 121 includes: a comparator U1, a Zener diode ZD1, resistors R8, R9, R10, and R11, and a capacitor C2. The first input terminal of the comparator U1 is connected to the first terminal of the Zener diode ZD1 and is connected to the first terminal of the switching circuit 110 through resistor R10. The second input terminal of the comparator U1 is connected to the second terminal of the switching circuit 110 through resistor R8, and is grounded through resistor R9 and capacitor C2. The output terminal of the comparator U1 is connected to the first terminal of the conduction control circuit 122 and to the first terminal of resistor R11. The second terminal of resistor R11 is connected to the second terminal of the conduction control circuit 122.

[0062] The comparator U1 is used to compare the first voltage at the first input terminal of the comparator U1 with the second voltage at the second input terminal of the comparator U1, and outputs a comparison voltage signal.

[0063] For example, resistor R8 can be 5.1kΩ, resistor R9 can be 5.6kΩ, resistor R10 can be 240Ω, the first input terminal of comparator U1 can be an inverting input terminal, and the second input terminal can be a non-inverting input terminal.

[0064] With S1 closed and S2 open, the first power supply 200 supplies power from one side only. The voltage at the inverting input terminal of comparator U1 is high, and the voltage at the non-inverting input terminal is low. The comparison voltage signal output by comparator U1 is a low-level voltage signal.

[0065] With S2 closed and S1 open, the second power supply 300 is powered on only one side. The voltage at the non-inverting input terminal of comparator U1 is high, and the voltage at the inverting input terminal is low. The comparison voltage signal output by comparator U1 is a high-level voltage signal.

[0066] With both S1 and S2 closed, the first power supply 200 and the second power supply 300 are powered from both sides. The voltage at the non-inverting input of comparator U1 is the voltage after the voltage of the second power supply 300 is divided by resistors R8 and R9, and the voltage at the inverting input is the voltage after the voltage of the first power supply 200 is divided by Zener diode ZD1 and resistor R10. The voltage at the non-inverting input of comparator U1 is higher, and the voltage at the inverting input is lower. The comparison voltage signal output by comparator U1 is a high-level voltage signal.

[0067] In some embodiments, the inverting input of comparator U1 can be connected to a reference source circuit to input a reference voltage to the inverting input of comparator U1.

[0068] In one possible implementation, see further. Figure 3The conduction control circuit 122 includes: diode D2, diode D3, resistor R12 and resistor R13. The cathode of diode D2 is connected to the second end of resistor R11 and to the first end of switch circuit 110, and is also grounded through resistor R12. The cathode of diode D3 is connected to the output terminal of comparator U1 and is also grounded through resistor R13. Diodes D2 and D3 are used to generate a first control signal or a second control signal based on the comparison voltage signal.

[0069] In an exemplary embodiment, the switching circuit 110 includes a first switching circuit 111 and a second switching circuit 112. The first terminal of the first switching circuit 111 is connected to the anodes of diodes D2 and D3, and the second terminal of the first switching circuit 111 is connected to the first terminal of the second switching circuit 112. The second terminal of the second switching circuit 112 is connected to the first power supply 200, and the third terminal of the second switching circuit 112 is connected to the second power supply 300.

[0070] The first switching circuit 111 is used to generate a conduction control signal according to a first control signal and a cutoff control signal according to a second control signal; the second switching circuit 112 is used to conduct the power supply and load according to the conduction control signal and disconnect the connection between the first power supply 200 and the second power supply 300 according to the cutoff control signal.

[0071] In one possible implementation, the first switching circuit 111 includes switching transistors Q3 and Q4, resistors R3, R4, R5, R6, and R7. The gate of switching transistor Q4 is connected to the anodes of diodes D2 and D3, respectively, and is connected to the second switching circuit through resistor R7. The source of switching transistor Q4 is grounded, and the drain of switching transistor Q4 is connected to the gate of switching transistor Q3, and is connected to the second power supply through resistor R5 and the first power supply through resistor R6. The source of switching transistor Q3 is grounded, and the drain of switching transistor Q3 is connected to the first terminal of resistor R4. The second terminal of resistor R4 is connected to the first terminal of the second switching circuit and is connected to the fourth terminal of the second switching circuit through resistor R3. Switches Q3 and Q4 are used to generate a turn-on control signal according to a first control signal and a cut-off control signal according to a second control signal.

[0072] In one possible implementation, the second switching circuit 112 includes: a switching transistor Q1 and a switching transistor Q2, the drain of the switching transistor Q1 is connected to a first power supply, the source of the switching transistor Q1 is connected to the source of the switching transistor Q2, the drain of the switching transistor Q2 is connected to a second power supply, and the gates of the switching transistor Q1 and the switching transistor Q2 are both connected to the second end of the resistor R4.

[0073] Switch Q1 and switch Q2 are used to turn on the power supply and load according to the turn-on control signal, and to disconnect the connection between the first power supply 200 and the second power supply 300 according to the cut-off control signal.

[0074] In one possible implementation, the switching transistor Q4 can be an NMOS transistor.

[0075] See Figure 3 With S1 closed and S2 open, the comparison voltage signal is a low-level voltage signal. The first power supply 200 provides a high level to the cathode of diode D2, so diode D2 is cut off. The cathode of diode D3 is at a low level, so diode D3 is grounded. Diodes D2 and D3 generate a first control signal at their positive terminals, i.e., the gate of switch Q4. Switch Q4 is cut off, and switch Q3 is turned on. Switch Q3 generates a conduction control signal at its drain. Switches Q1 and Q2 are both turned on based on the conduction control signal, so the power supply can supply power to the first load and the second load.

[0076] See Figure 4 With S2 closed and S1 open, the comparison voltage signal is a high-level voltage signal, and the voltage divided signal after passing through resistor R11 is a low-level voltage signal. The cathode of diode D2 is at a low level, and diode D2 is grounded. The cathode of diode D3 is at a high level, and diode D3 is cut off. Diodes D2 and D3 generate the first control signal at their anodes. Switch Q4 is cut off, and switch Q3 is turned on. Switch Q3 generates a conduction control signal at its drain. Switches Q1 and Q2 are both turned on based on the conduction control signal, and the power supply can supply power to the first and second loads.

[0077] See Figure 5 With both S1 and S2 closed, the first power supply 200 and the second power supply 300 provide power from both sides. The cathodes of diodes D2 and D3 are both at a high level, and both diodes D2 and D3 are cut off. Resistor R7 acts as a pull-up resistor, pulling the gate voltage signal of switch Q4 to a high level, turning on switch Q4 and turning off switch Q3. Switch Q3 generates a low-level cutoff control signal at its drain. The gates of switches Q1 and Q2 are pulled high through R3, and both switches Q1 and Q2 are cut off. The first power supply 200 supplies power only to the first load, and the second power supply 300 supplies power only to the second load.

[0078] In this embodiment of the application, when dual power supplies are powered simultaneously, the switching circuit 110 uses two back-to-back PMOS transistors Q1 and Q2 to connect or cut off the power supplies, which can effectively prevent current backflow between the two power supplies, avoid possible overcurrent or voltage conflicts, protect the load, and improve the reliability of the dual power supply anti-backflow circuit 100.

[0079] In one possible implementation, the first switching circuit further includes a capacitor C1, with a first terminal of the capacitor C1 connected to the gate of the switching transistor Q3 and a second terminal of the capacitor C1 grounded.

[0080] When the gate voltage of the switching transistor Q3 needs to change, capacitor C1 needs to charge and discharge, introducing a time delay into the circuit. This ensures that comparator U1 responds quickly to the voltage change first, and then, under the influence of the comparison voltage signal output by comparator U1, the power supply and load are turned on or off, thereby improving the stability and reliability of the circuit.

[0081] In an exemplary embodiment, the circuit may further include a diode D1, with a first terminal of diode D1 connected to a first power supply 200 and a second terminal of diode D1 connected to a first terminal of switching circuit 110. Exemplarily, diode D1 may be a non-Schottky diode, such as a PN junction diode made of silicon.

[0082] In this embodiment, the forward voltage drop of diode D1 is larger than that of Schottky diode, and its value range can be between 0.6V and 0.7V, or 0.8V to 1V when the current is large, so as to effectively achieve voltage isolation, thereby providing comparison logic for comparator U1 and ensuring the safety and stability of the dual power supply anti-backflow circuit 100.

[0083] In one exemplary embodiment, a dual-power reverse-current protection circuit 100 is provided. This circuit includes: a voltage comparator circuit 121, a conduction control circuit 122, a first switching circuit 111, a second switching circuit 112, and a diode D1, wherein:

[0084] The voltage comparison circuit 121 includes: a comparator U1, a Zener diode ZD1, resistors R8, R9, R10, and R11, and a capacitor C2. The first input terminal of the comparator U1 is connected to the first terminal of the Zener diode ZD1 and is connected to the first terminal of the switching circuit through resistor R10. The second input terminal of the comparator U1 is connected to the second terminal of the switching circuit through resistor R8, and is grounded through resistor R9 and capacitor C2. The output terminal of the comparator U1 is connected to the first terminal of the turn-on control circuit and to the first terminal of resistor R11. The second terminal of resistor R11 is connected to the second terminal of the turn-on control circuit 122. The comparator U1 is used to compare the first voltage at the first input terminal of the comparator U1 and the second voltage at the second input terminal of the comparator U1, and outputs a comparison voltage signal.

[0085] The conduction control circuit 122 includes: diode D2, diode D3, resistor R12 and resistor R13. The cathode of diode D2 is connected to the second end of resistor R11 and to the first end of the switching circuit, and is also grounded through resistor R12. The cathode of diode D3 is connected to the output terminal of comparator U1 and is also grounded through resistor R13. Diodes D2 and D3 are used to generate a first control signal or a second control signal based on the comparison voltage signal.

[0086] The first switching circuit 111 includes switching transistors Q3 and Q4, resistors R3, R4, R5, R6, and R7, and capacitor C1. The gate of switching transistor Q4 is connected to the anodes of diodes D2 and D3, and is connected to the second switching circuit through resistor R7. The source of switching transistor Q4 is grounded, and the drain of switching transistor Q4 is connected to the gate of switching transistor Q3, and is connected to the second power supply through resistor R5 and the first power supply through resistor R6. The source of switching transistor Q3 is grounded, and the drain of switching transistor Q3 is connected to the first terminal of resistor R4. The second terminal of resistor R4 is connected to the first terminal of the second switching circuit and to the fourth terminal of the second switching circuit through resistor R3. Switches Q3 and Q4 are used to generate a turn-on control signal based on a first control signal and a cut-off control signal based on a second control signal. The first terminal of capacitor C1 is connected to the gate of switching transistor Q3, and the second terminal of capacitor C1 is grounded.

[0087] The second switching circuit 112 includes: a switching transistor Q1 and a switching transistor Q2. The drain of the switching transistor Q1 is connected to the negative terminal of the diode D1, the positive terminal of the diode D1 is connected to the first power supply, the source of the switching transistor Q1 is connected to the source of the switching transistor Q2, the drain of the switching transistor Q2 is connected to the second power supply, and the gates of the switching transistors Q1 and Q2 are both connected to the second terminal of the resistor R4. The switching transistors Q1 and Q2 are used to turn on the power supply and the load according to the turn-on control signal, and to disconnect the connection between the first power supply and the second power supply according to the cut-off control signal.

[0088] In one exemplary embodiment, a dual-power backflow prevention system is provided, including a first power supply 200, a second power supply 300, and a dual-power backflow prevention circuit 100 as described in the above embodiment.

[0089] In an exemplary embodiment, the provided dual-power backflow prevention circuit 100 includes: a switching circuit and a control circuit. A first terminal of the switching circuit is used to connect to a first power supply 200, and a second terminal of the switching circuit is used to connect to a second power supply 300. A first terminal of the control circuit is connected to the first terminal of the switching circuit, a second terminal of the control circuit is connected to the second terminal of the switching circuit, and a third terminal of the control circuit is connected to the third terminal of the switching circuit. The control circuit is used to generate a first control signal when either the first power supply 200 or the second power supply 300 is used as a power source, and to generate a second control signal when both the first power supply 200 and the second power supply 300 are used as power sources. The switching circuit is used to connect the power supply and the load according to the first control signal, and to disconnect the connection between the first power supply 200 and the second power supply 300 according to the second control signal.

[0090] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A dual-power anti-backflow circuit, characterized in that, The dual-power backflow prevention circuit includes a switching circuit and a control circuit. The first terminal of the switching circuit is used to connect to a first power source, and the second terminal of the switching circuit is used to connect to a second power source. The first terminal of the control circuit is connected to the first terminal of the switching circuit, the second terminal of the control circuit is connected to the second terminal of the switching circuit, and the third terminal of the control circuit is connected to the third terminal of the switching circuit. The control circuit is used to generate a first control signal when the first power supply or the second power supply is used as the power supply, and to generate a second control signal when both the first power supply and the second power supply are used as the power supply. The switching circuit is used to connect the power supply and the load according to the first control signal, and disconnect the connection between the first power supply and the second power supply according to the second control signal.

2. The dual supply backflow prevention circuit of claim 1, wherein, The control circuit includes a voltage comparison circuit and a conduction control circuit; The first input terminal of the voltage comparison circuit is connected to the first terminal of the switching circuit, the second input terminal of the voltage comparison circuit is connected to the second terminal of the switching circuit, and the output terminal of the voltage comparison circuit is connected to the first terminal and the second terminal of the conduction control circuit, respectively. The third terminal of the conduction control circuit is connected to the third terminal of the switching circuit; The voltage comparison circuit is used to compare the voltage at the first terminal of the switching circuit with the voltage at the second terminal of the switching circuit, and output a comparison voltage signal. The conduction control circuit is used to generate the first control signal or the second control signal based on the comparison voltage signal.

3. The dual supply backflow prevention circuit of claim 2, wherein, The voltage comparison circuit includes: comparator U1, Zener diode ZD1, resistors R8, R9, R10, R11, and capacitor C2. The first input terminal of comparator U1 is connected to the first terminal of the Zener diode ZD1, and is also connected to the first terminal of the switching circuit through resistor R10; the second input terminal of comparator U1 is connected to the second terminal of the switching circuit through resistor R8, and is grounded through resistor R9 and capacitor C2; the output terminal of comparator U1 is connected to the first terminal of the conduction control circuit and to the first terminal of resistor R11; the second terminal of resistor R11 is connected to the second terminal of the conduction control circuit. The comparator U1 is used to compare the first voltage at the first input terminal of the comparator U1 with the second voltage at the second input terminal of the comparator U1, and output the comparison voltage signal.

4. The dual supply backflow prevention circuit of claim 3, wherein, The conduction control circuit includes: diode D2, diode D3, resistor R12, and resistor R13. The negative terminal of diode D2 is connected to the second terminal of resistor R11 and to the first terminal of the switching circuit, and is also grounded through resistor R12; The negative terminal of diode D3 is connected to the output terminal of comparator U1 and is also grounded through resistor R13; The diodes D2 and D3 are used to generate the first control signal or the second control signal based on the comparison voltage signal.

5. The dual supply backflow prevention circuit of claim 4, wherein, The switching circuit includes a first switching circuit and a second switching circuit. The first terminal of the first switching circuit is connected to the anode of diode D2 and the anode of diode D3, and the second terminal of the first switching circuit is connected to the first terminal of the second switching circuit. The second terminal of the second switching circuit is connected to the first power supply, and the third terminal of the second switching circuit is connected to the second power supply. The first switching circuit is used to generate a conduction control signal according to the first control signal and a cutoff control signal according to the second control signal; The second switching circuit is used to turn on the power supply and the load according to the turn-on control signal, and to disconnect the connection between the first power supply and the second power supply according to the cut-off control signal.

6. The dual supply backflow prevention circuit of claim 5, wherein, The first switching circuit includes switching transistor Q3, switching transistor Q4, resistors R3, R4, R5, R6, and R7. The gate of the switching transistor Q4 is connected to the anodes of the diodes D2 and D3 respectively, and is connected to the second switching circuit through the resistor R7. The source of the switching transistor Q4 is grounded, the drain of the switching transistor Q4 is connected to the gate of the switching transistor Q3, and is connected to the second power supply through the resistor R5 and the first power supply through the resistor R6. The source of the switching transistor Q3 is grounded, and the drain of the switching transistor Q3 is connected to the first end of the resistor R4. The second end of the resistor R4 is connected to the first end of the second switching circuit, and is connected to the fourth end of the second switching circuit through the resistor R3. The switching transistors Q3 and Q4 are used to generate the turn-on control signal according to the first control signal and the cut-off control signal according to the second control signal.

7. The dual supply backflow prevention circuit of claim 6, wherein, The second switching circuit includes: switching transistor Q1 and switching transistor Q2. The drain of the switching transistor Q1 is connected to the first power supply, the source of the switching transistor Q1 is connected to the source of the switching transistor Q2, the drain of the switching transistor Q2 is connected to the second power supply, and the gates of the switching transistor Q1 and the switching transistor Q2 are both connected to the second end of the resistor R4. The switching transistors Q1 and Q2 are used to turn on the power supply and the load according to the turn-on control signal, and to disconnect the connection between the first power supply and the second power supply according to the cut-off control signal.

8. The dual supply backflow prevention circuit of claim 7, wherein, The first switching circuit also includes a capacitor C1. The first terminal of capacitor C1 is connected to the gate of the switching transistor Q3, and the second terminal of capacitor C1 is grounded.

9. The dual supply backflow prevention circuit of claim 1, wherein, Also includes: Diode D1, the positive terminal of diode D1 is connected to the first power supply, and the negative terminal of diode D1 is connected to the first terminal of the switching circuit.

10. A dual power anti-backflow system, characterized by, It includes a first power supply, a second power supply, and a dual-power anti-backflow circuit according to any one of claims 1-9.

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