Current backflow prevention circuit, dual power supply current backflow prevention circuit and electronic equipment

Abstract

The present application relates to the technical field of power supply circuits, and discloses a current backflow prevention circuit, a dual power supply current backflow prevention circuit, and an electronic device. The current backflow prevention circuit includes: a conduction control module, a voltage hysteresis comparison module; the voltage hysteresis comparison module, the two input ends of which are respectively connected to the first end and the second end of the conduction control module, and the output end is connected to the third end of the conduction control module; the voltage hysteresis comparison module is used to compare the voltage of the first end and the voltage of the second end of the conduction control module after connecting to the power supply, and output a corresponding level signal according to the comparison result; the conduction control module is arranged in the power supply path between the power supply and the load, and is used to conduct the first end and the second end when receiving a level signal of a first state, so as to conduct the power supply path; when receiving a level signal of a second state, the first end and the second end are turned off to turn off the power supply path. The present application can prevent the load from backflowing the current of the power supply.

Description

Technical Field

[0001] The present application relates to the technical field of power supply circuits, and in particular to a current backflow prevention circuit, a dual power supply current backflow prevention circuit, and an electronic device. Background Art

[0002] For the downstream loads used in industrial scenarios, their reliability and stability will have higher requirements. Industrial downstream loads are often powered by dual power supplies, which can be powered by the other power supply when one power supply fails. For downstream loads powered by dual power supplies, the existing power supply switching technology uses two diodes in parallel, or two PMOS in series at the negative pole of the power supply, and one NMOS in series at the positive pole of the main power supply, and realizes the switching of the main and auxiliary power supplies by controlling the voltage difference between the gate and source of the MOS tube.

[0003] Since the diode voltage drop can reach 0.7V, the circuit loss on the diode is relatively large, and when the two voltages are similar, both power supply paths may be turned on. At this time, the two power supplies supply power to the subsequent load at the same time, and the MOS tube may not be fully turned on, resulting in power supply abnormalities, which will cause unreliable and unstable power supply to the subsequent load. Utility Model Content

[0004] In view of this, the embodiments of the present application provide a current backflow prevention circuit, a dual-power supply current backflow prevention circuit and an electronic device, which can solve the problems of large circuit losses on diodes and unstable dual-power supply switching, ensure the stability and reliability of power supply to subsequent loads, and achieve the effect of current backflow prevention.

[0005] In a first aspect, an embodiment of the present application provides a current backflow prevention circuit, including: a conduction control module, a voltage hysteresis comparison module;

[0006] The voltage hysteresis comparison module has two input terminals connected to the first terminal and the second terminal of the conduction control module respectively, and an output terminal connected to the third terminal of the conduction control module; the voltage hysteresis comparison module is used to compare the voltage of the first terminal and the voltage of the second terminal of the conduction control module after connecting to the power supply, and output a corresponding level signal according to the comparison result;

[0007] The conduction control module is arranged in the power supply path between the power supply and the load, and is used to make the first end and the second end conductive to conduct the power supply path when a level signal of a first state is received; and to make the first end and the second end disconnected to disconnect the power supply path when a level signal of a second state is received.

[0008] In some embodiments, further comprising: a first zener diode and a second zener diode;

[0009] The anode of the first Zener diode is connected to the anode of the second Zener diode, and the cathode of the first Zener diode is connected to the cathode of the output end of the power supply; the cathode of the second Zener diode is connected to the connection line between the conduction control module and the load.

[0010] In some embodiments, the conduction control module includes a MOS tube; the voltage hysteresis comparison module includes a hysteresis comparator;

[0011] The drain of the MOS tube is connected to the inverting input terminal of the hysteresis comparator; the source of the MOS tube is connected to the non-inverting input terminal of the hysteresis comparator; and the output terminal of the hysteresis comparator is connected to the gate of the MOS.

[0012] In some embodiments, the circuit also includes a positive feedback resistor; one end of the positive feedback resistor is connected to the connecting line between the MOS tube source and the non-phase input terminal of the hysteresis comparator; the other end of the positive feedback resistor is connected to the connecting line between the MOS tube gate and the output terminal of the hysteresis comparator.

[0013] In some embodiments, a current limiting module is further provided between the conduction control module and the voltage hysteresis comparison module;

[0014] The current limiting module includes a first current limiting resistor, a second current limiting resistor and a third current limiting resistor;

[0015] The first current limiting resistor is arranged between the first end and the first input end of the voltage hysteresis comparison module;

[0016] The second current limiting resistor is arranged between the second end and the second input end of the voltage hysteresis comparison module;

[0017] The third current limiting resistor is arranged between the output terminal of the voltage hysteresis comparison module and the third terminal.

[0018] In some embodiments, the circuit further includes a voltage-dividing resistor; one end of the voltage-dividing resistor is connected to a connecting line between the first current-limiting resistor and the first input terminal; the other end of the voltage-dividing resistor is connected to a negative output terminal of the power supply.

[0019] In some embodiments, the circuit also includes a pull-up resistor; one end of the pull-up resistor is connected to the connection line between the hysteresis comparator output and the MOS tube gate; the other end of the pull-up resistor is connected to the connection line between the MOS tube source and the load.

[0020] In a second aspect, an embodiment of the present application provides a dual-power supply current backflow prevention circuit, comprising two current backflow prevention circuits as described above; output lines of the two current backflow prevention circuits are connected to a load after being joined.

[0021] In some embodiments, the power supply voltages of the two current backflow prevention circuits are different;

[0022] The power supply voltages of the power supplies in the two current backflow prevention circuits are different;

[0023] When the first power supply voltage of the first power supply in the first current backflow prevention circuit is greater than the second power supply voltage of the second power supply in the second current backflow prevention circuit, the conduction control module of the first current backflow prevention circuit is turned on, and then the first power supply is used to supply power to the load;

[0024] When the first supply voltage of the first power supply in the first current backflow prevention circuit is lower than the second supply voltage of the second power supply in the second current backflow prevention circuit, the conduction control module of the second current backflow prevention circuit is turned on, and then the second power supply is used to power the load.

[0025] In a third aspect, an embodiment of the present application provides an electronic device, including the current backflow prevention circuit as described above, or the dual power supply current backflow prevention circuit as described above.

[0026] The embodiments of the present application have the following beneficial effects:

[0027] In this embodiment, a conduction control module and a voltage hysteresis comparison module are set up. The voltage of the first end and the second end of the conduction control module are compared through the voltage hysteresis comparison module, and a corresponding level signal is output according to the comparison result. After receiving the level signal, the conduction control module determines whether the first end and the second end are turned on or off according to the state of the level signal, thereby realizing normal power supply to the load or shutting off the power supply path when current backflow occurs.

[0028] The dual power supply current backflow prevention circuit of this embodiment includes two current backflow prevention circuits. The output lines of the two current backflow prevention circuits are connected to the load after being merged, so that when one power supply fails and the power is cut off, it can stably switch to another power supply to supply power to the subsequent load. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A connection diagram of a current backflow prevention circuit according to an embodiment of the present application is shown;

[0031] Figure 2 A circuit diagram of a current backflow prevention circuit according to an embodiment of the present application is shown;

[0032] Figure 3 A connection diagram of a dual power supply current backflow prevention circuit according to an embodiment of the present application is shown;

[0033] Figure 4 A circuit diagram of a dual power supply current backflow prevention circuit according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0034] 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.

[0035] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0036] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0037] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0038] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0039] The following describes the anti-current backflow power supply circuit, the anti-current backflow dual power supply circuit and the power supply equipment in the embodiments of the present application in combination with some specific embodiments.

[0040] Example 1

[0041] Figure 1 A connection diagram of a current backflow prevention circuit according to an embodiment of the present application is shown.

[0042] For example, Figure 1 The current backflow prevention circuit shown includes a conduction control module 100 and a voltage hysteresis comparison module 200. The conduction control module 100 is connected to a power supply, and the conduction control module 100 is also connected to the voltage hysteresis comparison module 200.

[0043] In this embodiment, the two input terminals of the voltage hysteresis comparison module 200 are respectively connected to the first terminal and the second terminal of the conduction control module 100, and the output terminal of the voltage hysteresis comparison module 200 is connected to the third terminal of the conduction control module 100; the voltage hysteresis comparison module 200 is used to compare the voltage of the first terminal and the voltage of the second terminal of the conduction control module 100 after connecting to the power supply, and output a corresponding level signal to the conduction control module 100 according to the comparison result. Among them, the level signal includes a level signal of a first state and a level signal of a second state.

[0044] The conduction control module 100 is disposed in the power supply path between the power supply and the load. When the conduction control module 100 receives a level signal of a first state, the first end and the second end are conducted to conduct the power supply path, thereby supplying power to the load; when the conduction control module 100 receives a level signal of a second state, the first end and the second end are disconnected to shut off the power supply path.

[0045] It can be understood that the description of "first" and "second" in the first state level signal and the second state level signal is only to distinguish the different level signals generated by the voltage hysteresis comparison module 200 in different situations. In actual use, the user can also set the second state level signal to connect the first end and the second end to conduct the power supply path; and set the first state level signal to disconnect the first end and the second end to disconnect the power supply path, which is not limited here.

[0046] In a specific embodiment, the conduction control module 100 includes a first terminal, a second terminal and a third terminal, and the voltage hysteresis comparison module 200 includes two input terminals and one output terminal. When the power supply is used, the current of the conduction control module 100 flows from the first terminal to the second terminal, and a voltage drop is formed between the first terminal and the second terminal; when the load has current backflow, the current flows from the second terminal to the first terminal of the conduction control module 100, and a voltage drop is formed between the first terminal and the second terminal; since the first terminal and the second terminal of the conduction control module 100 are respectively connected to the two input terminals of the voltage hysteresis comparison module 200, the voltage of the first terminal and the voltage of the second terminal are output to the voltage hysteresis comparison module 200 through the two input terminals of the voltage hysteresis comparison module 200, and the voltage hysteresis comparison module 200 outputs the voltage hysteresis comparison module 200 by comparing the first terminal with the voltage hysteresis comparison module 200. The voltage at the first end is compared with the voltage at the second end, and a corresponding high-level signal or a low-level signal is output according to the comparison result, and the high-level signal or the low-level signal is transmitted to the third end of the conduction control module 100 through the output end; usually, when the power supply is normally supplying power, the voltage at the first end is greater than the voltage at the second end, then the voltage hysteresis comparison module 200 outputs a low-level signal to the third end of the conduction control module 100, and the first end and the second end are turned on, so that the power supply can supply power to the load normally; if the third end receives a high-level signal, it means that current backflow occurs, and the first end and the second end are turned off to turn off the power supply of the power supply.

[0047] Combine the following Figure 2 A specific implementation of this embodiment is described.

[0048] The conduction control module 100 includes a MOS tube Q, wherein the MOS tube Q is a PMOS tube; the voltage hysteresis comparison module 200 includes a hysteresis comparator U. The drain of the MOS tube Q is connected to the positive electrode of the output terminal of the power supply DC, and the drain of the MOS tube Q is connected to the inverting input terminal of the hysteresis comparator U; the source of the MOS tube Q is connected to the positive input terminal of the hysteresis comparator U; and the output terminal of the hysteresis comparator U is connected to the gate of the MOS tube Q. In this embodiment, the hysteresis comparator U is used to make the comparator output more stable, and the fluctuation of the power supply can be avoided to interfere with the comparator, so that the hysteresis comparator will output the switching control only when the power supply DC has a certain switching change.

[0049] When the hysteresis comparator U is powered by the power supply DC, the current flows to the source through the drain of the MOS tube Q connected in series with the power supply DC, thereby supplying power to the load; the drain of the MOS tube Q is connected to the inverting input terminal of the hysteresis comparator U; the source of the MOS tube Q is connected to the non-inverting input terminal of the hysteresis comparator U; the output terminal of the hysteresis comparator U is connected to the gate of the MOS.

[0050] Specifically, when the power supply DC is normally powered, the current flows to the source through the drain of the MOS tube Q connected in series to the positive electrode of the power supply DC. Since the MOS tube Q has an on-resistance, there will be a slight voltage drop from the drain to the source of the MOS tube Q, and the voltage drop is usually 0.7V. The drain of the MOS tube Q is connected to the inverting input of the hysteresis comparator U; the source of the MOS tube Q is connected to the positive input of the hysteresis comparator U. When the power supply is normally supplied, since there is a voltage drop when the MOS tube Q is turned on, the drain voltage of the MOS tube Q is higher than the source voltage, and then the voltage difference between the positive input voltage and the inverting input voltage of the hysteresis comparator U is negative, so the hysteresis comparator U outputs a low-level signal. The output end of the hysteresis comparator U is connected to the gate of the MOS tube Q. Since the output end of the hysteresis comparator U outputs a low-level signal, the gate voltage of the MOS tube Q is less than the source voltage of the MOS tube Q, and the MOS tube Q is fully turned on, and the power supply DC supplies power to the subsequent load F.

[0051] When the backflow of current occurs in the subsequent load F, the current flows from the source to the drain of the MOS tube Q, and a voltage drop occurs from the source to the drain. At this time, the positive input voltage of the hysteresis comparator U is higher than the reverse input voltage, the output terminal of the hysteresis comparator U outputs a high-level signal, the gate voltage of the MOS tube Q is higher than the source voltage, and the MOS tube Q is turned off, thereby realizing the function of timely shutting off the power supply DC when the backflow of current occurs in the subsequent load F to the power supply DC, thereby preventing the backflow of current from the subsequent load F to the power supply DC.

[0052] In some specific implementations, a first current limiting resistor R1 is connected between the drain of the MOS tube Q and the inverting input terminal of the hysteresis comparator U; a second current limiting resistor R2 is connected between the source of the MOS tube Q and the non-inverting input terminal of the hysteresis comparator U; and a third current limiting resistor R3 is connected between the gate of the MOS tube Q and the output terminal of the hysteresis comparator U. This is to prevent the hysteresis comparator U or the MOS tube Q from being damaged by excessive current in the circuit.

[0053] In this embodiment, the current backflow prevention circuit also includes a positive feedback resistor R4; one end of the positive feedback resistor R4 is connected to the connection line between the second current limiting resistor R2 and the non-phase input end of the hysteresis comparator U; the other end of the positive feedback resistor R4 is connected to the connection line between the gate of the MOS tube Q and the output end of the hysteresis comparator U. The setting of the positive feedback resistor R4 can prevent the circuit from oscillating.

[0054] In this embodiment, the current backflow prevention circuit also includes a first voltage zener diode D1 and a second voltage zener diode D2; the cathode of the first voltage zener diode D1 is connected to the cathode of the power supply DC; the cathode of the second voltage zener diode D2 is connected to the output line of the current backflow prevention circuit; the anode of the first voltage zener diode D1 is connected to the anode of the second voltage zener diode D2. The first voltage zener diode D1 is used to prevent the negative electrode of the power supply DC from backflowing current, and the second voltage zener diode D2 is mainly used for circuit overvoltage protection; the fourth current limiting resistor R7 is connected between the cathode of the power supply DC and the first voltage zener diode D1.

[0055] In this embodiment, the current backflow prevention circuit further includes a voltage-dividing resistor R5; one end of the voltage-dividing resistor R5 is connected to the connection line between the first current-limiting resistor R1 and the inverting input end of the hysteresis comparator U; the other end of the voltage-dividing resistor R5 is connected to the connection line between the positive end of the first voltage-stabilizing diode D1 and the second voltage-stabilizing diode D2. In this embodiment, the voltage-dividing resistor R5 is used to provide a stable level state for the inverting input end of the hysteresis comparator U.

[0056] In this embodiment, the current backflow prevention circuit further includes a pull-up resistor R6; one end of the pull-up resistor R6 is connected to the connection line between the output end of the hysteresis comparator U and the gate of the MOS tube Q; the other end of the pull-up resistor R6 is connected to the connection line between the source of the MOS tube Q and the load F. The pull-up resistor R6 of this embodiment is used to provide a certain level when the hysteresis comparator U is not in operation.

[0057] In this embodiment, a conduction control module 100 and a voltage hysteresis comparison module 200 are provided. The voltage hysteresis comparison module 200 compares the voltages of the first end and the second end of the conduction control module 100, and outputs a corresponding level signal according to the comparison result. After receiving the level signal, the conduction control module 100 determines whether the first end and the second end are turned on or off according to the state of the level signal, thereby realizing normal power supply to the load or shutting off the power supply path when current backflow occurs.

[0058] Specifically, a MOS tube Q and a hysteresis comparator U are arranged on the power supply circuit, and the drain of the MOS tube Q is connected to the inverting input terminal of the hysteresis comparator U; the source of the MOS tube Q is connected to the non-inverting input terminal of the hysteresis comparator U; the output terminal of the hysteresis comparator U is connected to the gate of the MOS tube, thereby realizing comparison of the voltages before and after the MOS tube Q connected in series on the positive electrode of the power supply DC, and then realizing the conduction and cutoff of the MOS tube Q through the voltage output by the hysteresis comparator U, thereby realizing the function of preventing the backflow of the power supply DC by the subsequent load F.

[0059] Example 2

[0060] Figure 3A connection diagram of a dual power supply current backflow prevention circuit according to an embodiment of the present application is shown;

[0061] As shown in the figure, each current backflow prevention circuit is provided with a voltage hysteresis comparison module 200, which determines which current backflow prevention circuit to use for power supply by comparing the voltage at the first end and the voltage at the second end of the conduction control module 100 connected in series to the positive pole of the power supply output end. If the voltage at the second end of one of the current backflow prevention circuits is higher than the voltage at the first end, it means that the voltage of the other current backflow prevention circuit is higher, and the power supply circuit with a higher input voltage is used as the main power supply circuit to supply power to the subsequent load, and the other power supply circuit is used as the auxiliary power supply circuit. When the main power supply circuit fails and loses power, the output of the voltage hysteresis comparison module switches from a high level to a low level to control the switch to the auxiliary power supply circuit to supply power to the subsequent load.

[0062] Figure 4 A circuit diagram of a dual power supply current backflow prevention circuit according to an embodiment of the present application is shown.

[0063] like Figure 4 As shown, the dual power supply current backflow prevention circuit in this embodiment includes two current backflow prevention circuits in Embodiment 1, and the output lines of the two current backflow prevention circuits are connected to the load after being joined.

[0064] To facilitate the description of the circuit of this embodiment, in this embodiment, the two current backflow prevention circuits are divided into a first current backflow prevention circuit and a second current backflow prevention circuit. The power supply in the first current backflow prevention circuit is the first power supply DC1, the MOS tube is the first MOS tube Q1, and the hysteresis comparator is the first hysteresis comparator U1; the power supply in the second current backflow prevention circuit is the second power supply DC2, the MOS tube is the second MOS tube Q2, and the hysteresis comparator is the second hysteresis comparator U2.

[0065] When the dual-power supply current backflow prevention circuit of this embodiment is in use, since the source of the first MOS tube Q1 is connected to the source of the second MOS tube Q2, if the first power supply voltage of the first power supply DC1 is greater than the second power supply voltage of the second power supply DC2, the source voltage of the second MOS tube Q2 is the source voltage of the first PMOS, but the drain voltage of the second MOS tube Q2 is still the second power supply voltage, so the source voltage of the second MOS tube Q2 is higher than the drain voltage of the second MOS tube Q2. At this time, the voltage difference between the non-phase input terminal and the inverting input terminal of the second hysteresis comparator U2 is positive, and the second hysteresis comparator U2 outputs a high level, so the gate voltage of the second MOS tube Q2 is equal to the source voltage, and the second MOS tube Q2 is turned off. At this time, the subsequent load F is powered by the first power supply DC1.

[0066] Similarly, if the first power supply voltage of the first power supply DC1 is less than the second power supply voltage of the second power supply DC2, the source voltage of the first MOS tube Q1 is the source voltage of the second PMOS, but the drain voltage of the first MOS tube Q1 is still the first power supply voltage, so the source voltage of the first MOS tube Q1 is higher than the drain voltage of the first MOS tube Q1. At this time, the voltage difference between the non-inverting input terminal and the inverting input terminal of the first hysteresis comparator U1 is positive, and the first hysteresis comparator U1 outputs a high level. Therefore, the gate voltage of the first MOS tube Q1 is equal to the source voltage, and the first MOS tube Q1 is turned off. At this time, the subsequent load F is powered by the second power supply DC2.

[0067] When the first power supply voltage of the first power supply DC1 is greater than the second power supply voltage of the second power supply DC2, and the first power supply DC1 is used to supply power to the subsequent load F, if a power supply failure occurs in the first power supply DC1, the voltage output by the first current backflow prevention power supply circuit is 0. Since the current direction of the second power supply DC2 is from the drain to the source of the second MOS tube Q2, the drain voltage of the second MOS tube Q2 is higher than the source voltage, and the voltage difference between the positive input terminal and the negative input terminal of the second hysteresis comparator U2 is negative. The second hysteresis comparator U2 outputs a low level, and the gate voltage of the second MOS tube Q2 is less than the source voltage. The second MOS tube Q2 is turned on, and then after a power supply failure occurs in the first power supply DC1, the second power supply DC2 can be directly switched to supply power to the subsequent load F.

[0068] Similarly, when the first power supply voltage of the first power supply DC1 is less than the second power supply voltage of the second power supply DC2, and the second power supply DC2 is used to supply power to the subsequent load F, if a power supply failure occurs in the second power supply DC2, the voltage output by the second current backflow protection power supply circuit is 0. Since the current direction of the first power supply DC1 is from the drain to the source of the first MOS tube Q1, the drain voltage of the first MOS tube Q1 is higher than the source voltage, and the voltage difference between the positive input terminal and the negative input terminal of the first hysteresis comparator U1 is negative. The first hysteresis comparator U1 outputs a low level, and the gate voltage of the first MOS tube Q1 is less than the source voltage. The first MOS tube Q1 is turned on, and then after a power supply failure occurs in the second power supply DC2, the first power supply DC1 can be directly switched to supply power to the subsequent load F.

[0069] In this embodiment, a hysteresis comparator is used in both the first current backflow prevention circuit and the second current backflow prevention circuit to compare the drain and source voltages of the MOS tube connected in series to the positive power supply. When the source voltage of one of the MOS tubes is higher than the drain voltage, it means that the voltage of the other power supply is higher, and the hysteresis comparator output controls the shutdown of the power supply with a lower voltage, so that when the two power supplies are powered at the same time, the power supply with a higher input voltage is used as the main power supply to supply power to the subsequent load F, and the other power supply is used as the auxiliary power supply. When the main power supply fails and loses power, the MOS tube on the auxiliary power supply switches from a voltage lower than the source voltage to a voltage higher than the source voltage, and the hysteresis comparator output switches from a high level to a low level to control the switch to the auxiliary power supply to supply power to the subsequent load F. Furthermore, the dual power supply circuit for preventing current backflow in this embodiment can not only prevent current backflow, but also realize that when one power supply fails, it can stably switch to another power supply to supply power to the subsequent load F.

[0070] Example 3

[0071] The embodiment of the present application provides a power supply device including the current backflow prevention circuit of embodiment 1, wherein the electronic device may include a power supply for preventing current backflow when supplying power to a subsequent load.

[0072] The embodiment of the present application also provides an electronic device including the dual power supply current backflow prevention circuit of embodiment 2. The electronic device may also include a power supply, which is used to not only avoid current backflow prevention when supplying power to the subsequent load, but also realize the switching of the power supply circuit in the power supply device.

[0073] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A current backflow prevention circuit, characterized in that: include: Conduction control module, voltage hysteresis comparison module; The voltage hysteresis comparison module has two input terminals connected to the first terminal and the second terminal of the conduction control module respectively, and an output terminal connected to the third terminal of the conduction control module; The voltage hysteresis comparison module is used to compare the voltage of the first terminal and the voltage of the second terminal of the conduction control module after the power supply is connected, and output a corresponding level signal according to the comparison result; The conduction control module is provided in the power supply path between the power supply and the load, and is used to conduct the first end and the second end to conduct the power supply path when receiving a level signal of a first state; When a level signal of a second state is received, the first end and the second end are disconnected to disconnect the power supply path.

2. The current backflow prevention circuit according to claim 1, characterized in that: Also includes: a first zener diode and a second zener diode; The anode of the first Zener diode is connected to the anode of the second Zener diode, and the cathode of the first Zener diode is connected to the cathode of the output end of the power supply; the cathode of the second Zener diode is connected to the connection line between the conduction control module and the load.

3. The current backflow prevention circuit according to claim 1, characterized in that: The conduction control module includes a MOS tube; the voltage hysteresis comparison module includes a hysteresis comparator; The drain of the MOS tube is connected to the inverting input terminal of the hysteresis comparator; the source of the MOS tube is connected to the non-inverting input terminal of the hysteresis comparator; and the output terminal of the hysteresis comparator is connected to the gate of the MOS.

4. The current backflow prevention circuit according to claim 3, characterized in that: The circuit also includes a positive feedback resistor; one end of the positive feedback resistor is connected to the connection line between the MOS tube source and the non-phase input end of the hysteresis comparator; the other end of the positive feedback resistor is connected to the connection line between the MOS tube gate and the output end of the hysteresis comparator.

5. The current backflow prevention circuit according to claim 1, characterized in that: A current limiting module is also provided between the conduction control module and the voltage hysteresis comparison module; The current limiting module includes a first current limiting resistor, a second current limiting resistor and a third current limiting resistor; The first current limiting resistor is arranged between the first end and the first input end of the voltage hysteresis comparison module; The second current limiting resistor is arranged between the second end and the second input end of the voltage hysteresis comparison module; The third current limiting resistor is arranged between the output terminal of the voltage hysteresis comparison module and the third terminal.

6. The current backflow prevention circuit according to claim 5, characterized in that: The circuit also includes a voltage-dividing resistor; one end of the voltage-dividing resistor is connected to the connection line between the first current-limiting resistor and the first input end; the other end of the voltage-dividing resistor is connected to the negative output terminal of the power supply.

7. The current backflow prevention circuit according to claim 3, characterized in that: The circuit also includes a pull-up resistor; one end of the pull-up resistor is connected to the connection line between the output end of the hysteresis comparator and the gate of the MOS tube; the other end of the pull-up resistor is connected to the connection line between the source of the MOS tube and the load.

8. A dual power supply current backflow prevention circuit, characterized in that: It comprises two current backflow prevention circuits as described in any one of claims 1 to 7; the output lines of the two current backflow prevention circuits are connected to a load after being joined.

9. The dual power supply current backflow prevention circuit according to claim 8, characterized in that: The power supply voltages of the power supplies in the two current backflow prevention circuits are different; When the first power supply voltage of the first power supply in the first current backflow prevention circuit is greater than the second power supply voltage of the second power supply in the second current backflow prevention circuit, the conduction control module of the first current backflow prevention circuit is turned on, and then the first power supply is used to supply power to the load; When the first supply voltage of the first power supply in the first current backflow prevention circuit is lower than the second supply voltage of the second power supply in the second current backflow prevention circuit, the conduction control module of the second current backflow prevention circuit is turned on, and then the second power supply is used to power the load.

10. An electronic device, characterized in that: It comprises the current backflow prevention circuit as described in any one of claims 1 to 7, or the dual power supply current backflow prevention circuit as described in any one of claims 8 to 9.

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