Backflow prevention components, power supplies and electronic equipment

Abstract

The utility model discloses an anti-backflow component, a power supply and an electronic device, the component comprising: a field effect tube connected between a power supply output terminal and a load input terminal; a first triode, the emitter of the first triode is connected to the source of the field effect tube, the collector of the first triode is connected to the gate of the field effect tube; a second triode, the emitter of the second triode is connected to the drain of the field effect tube, the base of the second triode is connected to the base of the first triode and the collector of the second triode. The embodiment of the utility model solves the technical problem of high energy consumption of the anti-backflow circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and in particular to an anti-backflow element, a power supply and an electronic device. Background Art

[0002] The anti-backflow circuit is a circuit in which current can only flow in one direction. In the power supply system, if a constant voltage switching power supply is used, the characteristic of this power supply is that it can only provide a constant voltage to the outside. When the output end of the power supply encounters a voltage higher than its output voltage, current backflow may occur, which will cause the output voltage to increase, and may cause the feedback loop of the switching power supply to fail, and in severe cases, even cause permanent damage to the power supply.

[0003] To address this problem, an anti-backflow diode is added between the output of the switching power supply and the input of the load. The function of this diode is to prevent the external current from flowing back to the output of the switching power supply, thereby realizing the anti-backflow function. However, the diode has a PN junction voltage drop when it is forward-conducting, which will lead to increased losses when the current is large and may cause the temperature to rise, which is disadvantageous in application scenarios that need to carry large currents. In addition, in some applications, it is generally practiced to use one or more composite tubes as anti-backflow components, but such components require an auxiliary power supply to function.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Utility Model Content

[0005] The embodiments of the utility model provide an adaptive backflow prevention element, a power supply and an electronic device, so as to at least solve the technical problem of high energy consumption of the backflow prevention circuit.

[0006] The first aspect of the embodiment of the utility model provides an anti-backflow element, including: a field effect tube connected between a power supply output terminal and a load input terminal; a first triode, the emitter of the first triode is connected to the source of the field effect tube, and the collector of the first triode is connected to the gate of the field effect tube; a second triode, the emitter of the second triode is connected to the drain of the field effect tube, and the base of the second triode is connected to the base of the first triode and the collector of the second triode.

[0007] A second aspect of the embodiments of the utility model provides a power supply, comprising the anti-backflow element of the above-mentioned embodiment.

[0008] A third aspect of the embodiments of the present utility model provides an electronic device, comprising the power supply of the above embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0010] Figure 1 It is a circuit diagram of a backflow prevention element provided in an embodiment of the utility model.

[0011] Explanation of the accompanying drawings: 100 represents the power output terminal, 200 represents the load input terminal, 300 represents the ground terminal, Q1 represents the second transistor, 11 represents the base of the second transistor, 12 represents the emitter of the second transistor, 13 represents the collector of the second transistor, Q2 represents the field effect transistor, 21 represents the gate of the field effect transistor, 22 represents the drain of the field effect transistor, 23 represents the source of the field effect transistor, Q3 represents the first transistor, 31 represents the base of the first transistor, 32 represents the emitter of the first transistor, 33 represents the collector of the first transistor, D1 represents the Zener diode, R1 represents the second grounding resistor, and R2 represents the first grounding resistor. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0013] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model 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 elements used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here. 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 clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0014] Unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances. In addition, words such as "exemplarily" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design scheme described as "exemplarily" or "for example" in the embodiments of the present utility model should not be interpreted as being more preferred or more advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplarily" or "for example" is intended to present related concepts in a specific way.

[0015] Please refer to Figure 1 The anti-backflow element is connected to the power output terminal 100 and the load input terminal 200 respectively. The power output terminal 100 is used to connect to the power supply ( Figure 1 The load input terminal 200 is used to connect to the load ( Figure 1 not shown) connection.

[0016] The backflow prevention element includes a field effect transistor Q2, which is connected between the power output terminal 100 and the load input terminal 200. In this way, by changing the state of the field effect transistor Q2, the current between the power output terminal 100 and the load input terminal 200 can be controlled. For example, when the field effect transistor Q2 is biased to the on state, the current can flow from the power output terminal 100 to the load input terminal 200; when the field effect transistor Q2 is not biased to the on state, the current may be limited and / or completely blocked.

[0017] The anti-backflow element also includes various components for selectively biasing the field effect transistor Q2, including a first transistor Q3 and a second transistor Q1, wherein the emitter 32 of the first transistor is connected to the source 23 of the field effect transistor, the collector 33 of the first transistor is connected to the gate 21 of the field effect transistor, the emitter 12 of the second transistor is connected to the drain 22 of the field effect transistor, the base 11 of the second transistor is connected to the base 31 of the first transistor and the collector 13 of the second transistor, the field effect transistor Q2 is a P-type field effect transistor, and the first transistor Q3 and the second transistor Q1 are both PNP transistors.

[0018] In some embodiments, please refer to Figure 1 The backflow prevention element further includes a first grounding resistor R2 and a second grounding resistor R1, wherein the first grounding resistor R2 is connected to the collector 33 of the first transistor, and the second grounding resistor R1 is connected to the collector 13 of the second transistor.

[0019] In this embodiment, when the voltage of the power output terminal 100 is higher than the voltage of the load input terminal 200, the second transistor Q1 and the second grounding resistor R1 together form a constant current source. At this time, the second transistor Q1 is turned on, causing the PN junction of the first transistor Q3 to be cut off due to the reverse voltage. At the same time, the first grounding resistor R2 serves as a bias resistor of the field effect transistor Q2, and its pull-down effect on the ground causes a voltage difference exceeding the gate-source threshold to be generated between the gate 21 and the source 23 of the field effect transistor. Therefore, the field effect transistor Q2 is turned on under the action of the bias voltage to supply power to the load input terminal 200. When the voltage of the power output terminal 100 is lower than the voltage of the load input terminal 200, the first transistor Q3 will be turned on. This conduction causes the gate 21 voltage of the field effect transistor Q2 to rise, causing the voltage difference between the gate 21 and the source 23 to be reduced to a voltage lower than the gate-source threshold voltage of the field effect transistor. Since the field effect transistor Q2 loses the required bias voltage, the field effect transistor Q2 will be cut off, thereby achieving the purpose of preventing current backflow.

[0020] In this embodiment, compared with using a Schottky diode, using a field effect transistor can reduce losses, is suitable for use scenarios with larger currents, and does not require additional power assistance, thereby reducing the energy consumption of the anti-backflow circuit.

[0021] In some embodiments, please refer to Figure 1 The collector 33 of the first transistor is connected to the load input terminal 200 through the Zener diode D1.

[0022] Specifically, the design and use of the Zener diode has the dual functions of clamping the bias voltage and the reverse voltage. When the bias voltage is too high, the diode clamps the bias voltage to prevent the bias voltage from being too high and breaking down the MOS. When the reverse voltage is too high, the diode clamps the reverse voltage to prevent the reverse voltage from being too high and breaking down the MOS, thereby playing a protective role. For example, when there is a bias voltage on the field effect transistor Q2, the Zener diode D1 is used to clamp the bias voltage to prevent the bias voltage from being too high and breaking down the gate 21 of the field effect transistor.

[0023] The above is only a preferred embodiment of the utility model patent, but the protection scope of the utility model patent is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the scope disclosed by the utility model patent according to the technical solution and utility model concept of the utility model patent, which are all within the protection scope of the utility model patent.

Claims

1. A backflow prevention element, characterized in that: include: A field effect transistor connected between the power supply output and the load input; A first triode, wherein the emitter of the first triode is connected to the source of the field effect tube, and the collector of the first triode is connected to the gate of the field effect tube; a second triode, wherein the emitter of the second triode is connected to the drain of the field effect tube, and the base of the second triode is connected to the base of the first triode and the collector of the second triode; Among them, the field effect transistor is a P-type field effect transistor, and the first transistor and the second transistor are both PNP transistors.

2. The backflow prevention element according to claim 1, characterized in that: It also includes a first grounding resistor connected to the collector of the first transistor.

3. The backflow prevention element according to claim 2, characterized in that: A second grounding resistor connected to the collector of the second transistor is also included.

4. The backflow prevention element according to any one of claims 1 to 3, characterized in that: The collector of the first transistor is connected to the load input terminal through a Zener diode.

5. A power supply, characterized in that: The invention comprises the backflow prevention element as claimed in any one of claims 1 to 4.

6. An electronic device, characterized in that: Comprising the power supply as claimed in claim 5.

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