Simple large-current dual-power-supply automatic switching power supply circuit
By using a switching circuit composed of MOSFETs and transistors, the problems of diode overheating and slow response in existing dual power supply systems are solved, enabling high current power supply and fast automatic switching, thus reducing costs.
Patent Information
- Application Number
- CN202520107412.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2026-01-16
- Estimated Expiration
- 2035-01-17
AI Technical Summary
In existing dual-power supply schemes, the diodes overheat severely when the load current is large, and the power supply response is slow, making it impossible to achieve rapid automatic switching of high current.
A switching circuit composed of field-effect transistors and bipolar transistors is used to achieve a simple circuit by utilizing the voltage drop of the field-effect transistors, thereby reducing costs and enabling fast and automatic response to power switching.
It achieves high current power supply while reducing circuit cost and can quickly respond to power switching, avoiding problems such as diode overheating and temporary load interruption.
Smart Images
Figure CN223809604U_ABST
Abstract
Description
Technical Field
[0001] This utility model specifically relates to a simple high-current dual-power automatic switching power supply circuit. Background Technology
[0002] Each of the two power supplies is connected in series with a rectifier diode to the output terminal. Due to the unidirectional conductivity of the diodes, the output voltage is always the highest voltage from the two power supplies. The disadvantages of this method are: the diodes overheat significantly as the load current increases, requiring high-power diodes to handle high-current applications. Furthermore, the dual power supplies lack priority, resulting in uncontrolled power supply operation.
[0003] For example, attached Figure 1 As shown, conventional dual power supply systems currently use two diodes that are isolated from each other for power supply. The biggest drawback of this circuit is that the load current cannot be too large, otherwise the isolated diodes will overheat severely.
[0004] The MCU detects the voltage of the dual power supplies and selectively turns on the corresponding power supply switch based on the connected power supply. The main drawback of this method is its slow response time; it requires the MCU to detect the correct voltage before it can execute the action, and the load briefly stops working during the switching process, affecting the user experience. Summary of the Invention
[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a simplified high-current dual-power automatic switching circuit, which features a simplified circuit design, reduced cost, high-current power supply capability, and rapid automatic response to power switching.
[0006] A simplified high-current dual-power automatic switching power supply circuit according to this utility model includes a first power input terminal VIN1 and a second power input terminal VIN2. Its characteristic is that it further includes a switching circuit, connecting the first power input terminal VIN1 and the second power input terminal VIN2. These components are connected to a switching circuit, which includes a first field-effect transistor Q1, a second field-effect transistor Q2, a third field-effect transistor Q3, and a transistor Q4. The output of the first power input terminal VIN1 is connected to the drain (D) of the second field-effect transistor Q2, the base (B) of the transistor Q4, and the gate (G) of the third field-effect transistor Q3. The gate (G) of the second field-effect transistor Q2 is connected to the collector (C) of the transistor Q4. The emitter (E) of the transistor Q4 is connected to the ground terminal GND. The gate (G) of the first field-effect transistor Q1 is connected to the gate (G) of the second field-effect transistor Q2. The source (S) of the first field-effect transistor Q1 is connected to the source (S) of the second field-effect transistor Q2. The drain (D) of the first field-effect transistor Q1 is connected to the source (S) of the third field-effect transistor Q3. The common terminal between the drain (D) of the first field-effect transistor Q1 and the third field-effect transistor Q3 is connected to the VOUT terminal.
[0007] Specifically further, the first power input end VIN1 is connected with the B pole of the transistor Q4 through the fourth resistance R4.
[0008] Specifically further, the G pole of the second field effect transistor Q2 is connected with the C pole of the transistor Q4 through the second resistance R2.
[0009] Specifically further, the common end between the G pole of the first field effect transistor Q1 and the G pole of the second field effect transistor Q2 is connected with the first resistance R1, and the common end between the S pole of the first field effect transistor Q1 and the D pole of the second field effect transistor Q2 is connected with the other end of the first resistance R1.
[0010] Specifically further, the first power input end VIN1 is connected with the G pole of the third field effect transistor Q3 through the third resistance R3.
[0011] Specifically further, the G pole of the third field effect transistor Q3 is connected with the common end of the third resistance R3 through the fifth resistance R5, the fifth resistance R5 is connected with the ground end GND, and the common end between the fifth resistance R5 and the ground end GND is connected with the VOUT end through the first capacitor.
[0012] The beneficial effects of the utility model are: the circuit is switched through the VIN1 end and the VIN2 end through the double power supply switching circuit, the VOUT value of the double power supply switching circuit is only about 0.2V lower than the VIN1 or VIN2 voltage, wherein, the D pole and the S pole between the first field effect transistor Q1, the second field effect transistor Q2 and the third field effect transistor Q3 of the double power supply switching circuit are used to implement voltage drop, compared with the prior art MCU detection double power supply circuit, the simple circuit and the reduced cost can be achieved; compared with the conventional double power supply circuit adopting two diodes, the circuit can supply large current and can quickly and automatically respond to power supply switching. BRIEF DESCRIPTION OF DRAWINGS
[0013] The above and / or additional aspects and advantages of the utility model will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings.
[0014] Figure 1 It is the circuit diagram of prior art.
[0015] Figure 2 It is the first power input end VIN1, the second power input end VIN2, the switching circuit and the load of the utility model are connected schematic view.
[0016] Figure 3 It is the double power supply switching circuit diagram of the utility model. DETAILED DESCRIPTION
[0017] The embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for explaining the present application, and cannot be understood as limiting the present application.
[0018] The embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for explaining the present application, and cannot be understood as limiting the present application. Figures 2 to 3 The embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for explaining the present application, and cannot be understood as limiting the present application.
[0019] The circuit is switched through the VIN1 end and the VIN2 end through the dual power supply switching circuit, and the VOUT value of the dual power supply switching circuit is only about 0.2V lower than the voltage of VIN1 or VIN2. Among them, the voltage drop between the D pole and the S pole of the first field effect tube Q1, the second field effect tube Q2 and the third field effect tube Q3 of the dual power supply switching circuit is used, compared with the existing MCU detection dual power supply circuit, which can realize simple circuit and reduce cost; compared with the conventional dual power supply circuit using two diodes, the circuit can realize large current power supply and fast automatic response to power supply switching.
[0020] The first power input end VIN1 and the B pole of the triode Q4 are connected through the fourth resistor R4. The fourth resistor R4 plays a role of limiting voltage, and is used for protecting the B pole of the triode Q4.
[0021] The G pole of the second field effect tube Q2 and the C pole of the triode Q4 are connected through the second resistor R2. The second resistor R2 plays a role of voltage division, and is used for protecting the second field effect tube Q2 and the triode Q4.
[0022] The common terminal between the G terminal of the first field effect transistor Q1 and the G terminal of the second field effect transistor Q2 is connected with the first resistor R1, and the common terminal between the S terminal of the first field effect transistor Q1 and the D terminal of the second field effect transistor Q2 is connected with the other end of the first resistor R1. The first resistor R1 prevents the simultaneous conduction of the upper and lower bridge arms, causing a short circuit.
[0023] The first power input terminal VIN1 and the G terminal of the third field effect transistor Q3 are connected through the third resistor R3. The third resistor R3 functions as a voltage limiter for protecting the G terminal of the third field effect transistor Q3.
[0024] The common terminal between the G terminal of the third field effect transistor Q3 and the third resistor R3 is connected with the fifth resistor R5, the fifth resistor R5 is connected with the ground terminal GND, and the common terminal between the fifth resistor R5 and the ground terminal GND is connected with the VOUT terminal through the first capacitor.
[0025] The application scenario of the circuit is that two power supplies supply power to the same load, and the overall power supply is not affected regardless of plugging in any power supply. The first power input terminal VIN1 and the second power input terminal VIN2 are equivalent to two power supplies, and the VOUT terminal is the output to the load. After the double power supply switching circuit, the voltage value of the VOUT terminal is only about 0.2V lower than that of the first power input terminal VIN1 or the second power input terminal VIN2, because of the voltage drop between the D terminal and the S terminal of the first field effect transistor Q1, the second field effect transistor Q2 and the third field effect transistor Q3.
[0026] When only the second power input terminal VIN2 is input, the second power input terminal VIN2 reaches the VOUT terminal through the third field effect transistor Q3. At this time, the Vsg of the third field effect transistor Q3 is the voltage of the second power input terminal VIN2, which satisfies the N field effect opening condition, and the third field effect transistor Q3 is completely turned on. At this time, the D terminal and the S terminal of the third field effect transistor Q3 are approximately short-circuited, and the voltage of the VOUT terminal is equal to the voltage of the second power input terminal VIN2.
[0027] When only the first power input terminal VIN1 is input, the voltage on the first power input terminal VIN1 opens the triode Q4 through the fourth resistor R4, and then the Vsg of the first field effect transistor Q1 and the second field effect transistor Q2 is (first resistor R1 / (first resistor R1+second resistor R2))*first power input terminal VIN1. Vsg is greater than the starting voltage (generally about 2V) of the first field effect transistor Q1 and the second field effect transistor Q2, so the first field effect transistor Q1 and the second field effect transistor Q2 are turned on at the same time, and the VOUT terminal is approximately short-circuited. The voltage of the VOUT terminal is equal to the voltage of the first power input terminal VIN1.
[0028] When the first power input terminal VIN1 and the second power input terminal VIN2 are input simultaneously, Vsg of the third field effect tube Q3 = VOUT terminal - (fifth resistor R5 / (third resistor R3 + fifth resistor R5)) * first power input terminal VIN1. Since the resistance value of the fifth resistor R5 is much greater than the resistance value of the third resistor R3, Vsg of the third field effect tube Q3 is approximately equal to the voltage of the VOUT terminal - the voltage of the first power input terminal VIN1, at this time, Vsg is less than or equal to 0, not meeting the N field effect starting voltage, the third field effect tube Q3 is closed, and the voltage of the VOUT terminal = the voltage of the first power input terminal VIN1.
[0029] Although the embodiments of the utility model have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the utility model, the scope of the utility model is defined by the claims and its equivalents.
Claims
1. A simple high-current dual power supply automatic switching power supply circuit, comprising a first power supply input terminal VIN1 and a second power supply input terminal VIN2, characterized in that: The switching circuit is connected with the first power input terminal VIN1 and the second power input terminal VIN2, and comprises a first field effect transistor Q1, a second field effect transistor Q2, a third field effect transistor Q3 and a triode Q4.
2. The simple high-current dual power supply automatic switching power supply circuit according to claim 1, characterized in that: The first power input terminal VIN1 is connected with the B electrode of the triode Q4 through the fourth resistor R4.
3. The simple high-current dual power supply automatic switching power supply circuit according to claim 1, characterized in that: The G electrode of the second field effect transistor Q2 is connected with the C electrode of the triode Q4 through the second resistor R2.
4. The automatic dual power supply switching circuit of claim 1, wherein: The G electrode of the first field effect transistor Q1 and the G electrode of the second field effect transistor Q2 are connected with the first resistor R1.
5. The simple high-current dual power supply automatic switching power supply circuit according to claim 1, characterized in that: The first power input terminal VIN1 is connected with the G electrode of the third field effect transistor Q3 through the third resistor R3.
6. The simple high-current dual power supply automatic switching power supply circuit according to claim 5, characterized in that: The G electrode of the third field effect transistor Q3 is connected with the fifth resistor R5 at the common terminal of the third resistor R3, the fifth resistor R5 is connected with the ground terminal GND, and the common terminal between the fifth resistor R5 and the ground terminal GND is connected with the VOUT terminal through the first capacitor.