Anti-backflow circuit
By using MOS tubes to replace diodes in anti-return circuits, the problems of diode heating and energy consumption are solved, lower energy consumption and higher safety are achieved, and electronic products such as lettering machines, cutting machines, 3D printers, labeling machines and film stickers are suitable for electronic products.
Patent Information
- Application Number
- CN202422005924.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2034-08-15
AI Technical Summary
In the prior art, when diodes are anti-returning devices, there are problems of heat generation and energy consumption, especially when high currents are backflowing, the loss may be significant, which may lead to equipment damage.
The MOS tube is used as the anti-backflow module. Through the coordination of the control module and the switching unit, the MOS tube isolates the impact of the rear end on the front end when the high current is backflow, reducing energy consumption and heating.
Compared with diodes, MOS tubes have smaller internal resistance and lower voltage drop, which can effectively isolate backflow current, reduce circuit heating and loss, and improve safety and current tolerance.
Smart Images
Figure CN223124599U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to electronic circuits, and more specifically, to an anti-backflow circuit. Background Art
[0002] In the design of electronic products such as engraving machines, cutting machines, 3D printers, label printers, and film laminating machines, electric motors are used, and the movement of the motors is controlled by a single-chip microcomputer. However, when the single-chip microcomputer is powered off and the rear-end motor is manually dragged, a reverse current will be generated, and the reverse current will flow back to the front-stage circuit on the side of the single-chip microcomputer. Generally, a diode is added for isolation. The diode is arranged between the front-stage circuit and the motor. The diode has the characteristic of unidirectional conductivity and can prevent current backflow or reverse flow.
[0003] Since the diode itself has a PN junction voltage drop, especially when the current is large, its heat generation is more obvious. For example: a common diode has a voltage drop of 0.4V between the PN junctions. When a 10A current flows back in reverse, the power of P = UI will be generated at the position of the diode, that is, a power of P = 0.4 * 10 = 4W. At this time, the power loss of the diode is large, and the most important thing is that it will continuously generate heat and may be damaged. Summary of the Utility Model
[0004] The purpose of this utility model is to provide an anti-backflow circuit, aiming to solve the technical problems of heat generation and energy consumption of diodes when using the unidirectional conductivity of diodes to achieve anti-backflow design in the prior art.
[0005] The anti-backflow circuit provided by this utility model includes:
[0006] An input terminal for inputting voltage to the rear end;
[0007] An output terminal for outputting voltage;
[0008] A control module for sending control signals;
[0009] A switch unit connected to the control module, for receiving the control signal and being in a conductive or off state under the control of the control signal, and then outputting a switch signal;
[0010] An anti-backflow module connected to the input terminal, the output terminal, and the switch unit, including at least one MOS transistor. The anti-backflow module receives the input voltage from the input terminal and sends the output voltage to the output terminal under the control of the switch unit;
[0011] Among them, the switch unit controls the anti-backflow module to conduct or cut off; when the circuit is powered off, the switch unit controls the anti-backflow module to cut off, and prevents the current from flowing back from the output terminal to the input terminal.
[0012] Regarding the anti-backflow circuit that uses MOS transistors, compared with the existing anti-backflow device using diodes, MOS transistors have a smaller internal resistance and a smaller voltage drop. When a large current flows back from the rear end, the MOS transistor itself is in the cut-off state, which can isolate the influence of the rear end on the input terminal of the front end. At the same time, the MOS transistor has lower energy consumption when passing through a large current, which can reduce the heat generation and loss of the entire anti-backflow circuit.
[0013] In the present utility model, when the anti-backflow circuit outputs voltage at the normal driving output terminal, the MOS transistor is more sensitive than the diode, and has higher voltage and current tolerance, and is safer. Brief Description of the Drawings
[0014] Figure 1 It is a schematic diagram of the principle and module of the anti-backflow circuit of the present utility model. Detailed Embodiments
[0015] The following further elaborates and explains the present utility model in conjunction with specific embodiments and the drawings of the specification:
[0016] Please refer to Figure 1 , the anti-backflow circuit 100 includes: an input terminal X, an output terminal Y, a control module 10, a switching unit 20, and an anti-backflow module 30. Among them, the input terminal X is connected to the output terminal Y through the anti-backflow module 30, and the anti-backflow module 30 is also connected to the switching unit 20, and the control module 10 is connected to the switching unit 20 to control the switching unit 20 and indirectly control the anti-backflow module 30 to work in the output state or the isolation state through the switching unit 20.
[0017] Among them, the input terminal X is used to input voltage to the rear end; the output terminal Y is used to output voltage; the control module 10 is used to send control signals; the switching unit 20 is used to receive the control signals and be in the on or off state under the control of the control signals, and then output switching signals; the anti-backflow module 30 includes at least one MOS transistor, and the anti-backflow module 30 receives the input voltage from the input terminal X and sends the output voltage to the output terminal Y under the control of the switching unit 20.
[0018] Among them, the switching unit 20 controls the anti-backflow module 30 to conduct or cut off; when the anti-backflow circuit 100 is powered off, the switching unit 20 controls the anti-backflow module 30 to cut off and prevents the current from flowing back from the output terminal Y into the input terminal X.
[0019] The anti-backflow circuit 100 uses MOS transistors. Compared with the existing anti-backflow devices using diodes, MOS transistors have a smaller internal resistance and a smaller voltage drop. When a large current flows back from the backend, the MOS transistor itself is in the cut-off state, which can isolate the influence of the backend on the input terminal X of the front end. At the same time, the MOS transistor has lower power consumption when passing through a large current, which can reduce the heat generation and loss of the entire anti-backflow circuit 100.
[0020] In the present utility model, when the anti-backflow circuit 100 outputs voltage at the normal drive output terminal Y, the MOS transistor is more sensitive than the diode, and has higher voltage and current tolerance, and is safer.
[0021] Among them, the control module 10 is a single-chip microcomputer. After the anti-backflow circuit 100 is powered off, the control module 10 outputs a control signal with a low level to the switch unit 20; the switch unit 20 includes an N-type first MOS transistor Q14. The gate G of the first MOS transistor Q14 is electrically connected to the control module 10, the source S of the first MOS transistor Q14 is grounded, and the drain D of the first MOS transistor Q14 is electrically connected to the anti-backflow module 30; when the gate G of the first MOS transistor Q14 receives the control signal with a low level, the first MOS transistor Q14 is cut off, and the switch unit 20 has no output, so that the anti-backflow module 30 stops working. Stopping working means stopping sending the output voltage to the output terminal Y.
[0022] In the present utility model, the anti-backflow module 30 includes: a P-type second MOS transistor Q11, a P-type third MOS transistor Q13, and a bias circuit 301.
[0023] Specifically, the drain D of the second MOS transistor Q11 is connected to the input terminal X, and the gate G of the second MOS transistor Q11 is connected to the drain D of the first MOS transistor Q14; the source S of the third MOS transistor Q13 is connected to the source S of the second MOS transistor Q11, the gate G of the third MOS transistor Q13 is connected to the gate G of the second MOS transistor Q11, and the drain D of the third MOS transistor Q13 is connected to the output terminal Y; the bias circuit 301 is connected between the source S and the gate G of the second MOS transistor Q11, and is used to adjust the voltage between the gate G and the source S of the second MOS transistor Q11. When the first MOS transistor is turned on, the second MOS transistor Q11 is in the leakage current working range to input voltage to the source of the third MOS transistor.
[0024] In the present utility model, the bias circuit 301 includes: a first resistor R144 and a zener diode ZD1.
[0025] One end of the first resistor R144 is connected to the source S of the second MOS transistor Q11, and the other end of the first resistor R144 is electrically connected to the gate G of the second MOS transistor Q11; the positive electrode of the zener diode ZD1 is electrically connected to the gate G of the second MOS transistor Q11, and the negative electrode of the zener diode ZD1 is connected to the source S of the second MOS transistor Q11; the voltage of the zener diode ZD1 enables the voltage between the source S and the gate G of the second MOS transistor Q11 and the third MOS transistor Q13 to be in the leakage current operating range.
[0026] Wherein, the anti-backflow circuit 100 further includes a second resistor R140, and the second resistor R140 is electrically connected between the bias circuit 301 and the drain D of the first MOS transistor Q14; after the anti-backflow circuit 100 is powered on, the control module 10 outputs a high-level control signal, so that the first MOS transistor Q14 is turned on, thereby pulling down the gates G of the second MOS transistor Q11 and the third MOS transistor Q13 to a low level. After the first resistor R144 and the second resistor R140 are voltage-divided, the voltage between the source and the gate of the second MOS transistor Q11 is in the leakage current operating range; the second MOS transistor Q11 is in the leakage current operating mode, and the third MOS transistor Q13 is turned on and in the normal conduction state, so as to realize the input terminal X to output a driving voltage to the output terminal Y.
[0027] The following is an explanation of the specific working process:
[0028] 1. When normally supplying power from the input terminal X to the output terminal Y
[0029] The control module 10 inputs a 3.3V high-level control signal to the switch unit 20, and the first MOS transistor Q14 of the switch unit 20 is turned on. At this time, the second MOS transistor Q11, the second resistor R140, the first resistor R144, and the first MOS transistor Q14 jointly divide the input voltage to form a conduction path, and a bias voltage is formed at points a and b in the circuit in the figure. After being regulated by the zener diode ZD1, it is maintained at 15V. At this time, the maximum Vgs voltage marked by the second MOS transistor Q11 is 20V, so as to ensure that the second MOS transistor Q11 will not be damaged. On the other hand, the second MOS transistor Q11 is not turned on, but is in the leakage current working state, that is, the 24V voltage of the input terminal X is applied to point a. When the first MOS transistor Q14 is turned on, it is equivalent to the drain of the first MOS transistor Q14 being grounded. At this time, the switching signal output by the first MOS transistor Q14 is a low level. Since the third MOS transistor is a P-type MOS transistor, the third MOS transistor Q13 is in the normal conduction state, and the voltage at point a is input to the output terminal Y through the third MOS transistor, that is, the drain D of the third MOS transistor Q13, thereby realizing normal power supply.
[0030] 2. When the anti-backflow circuit is powered off
[0031] When the control module 10 is powered off, the control module 10 has no output, which is equivalent to a low level. At this time, the first MOS tube Q14 in the switch unit 20 is turned off, and the input voltage has the same drain voltage at point a and point b through the second MOS tube Q11. At this time, the conduction path of the second resistor R140, the first resistor R144 and the first MOS tube Q14 is cut off. When the first MOS tube Q14 has no output, the gate G voltage of the third MOS tube Q13 is a drain voltage, which is a high level. At this time, the third MOS tube Q13 is turned off, and the voltage of the input terminal X cannot be supplied to the output terminal Y.
[0032] At this time, when the output terminal Y flows from the drain D of the third MOS tube Q13 to the source S because of the reverse current flowing into the driving motor, it also shows a leakage voltage. The reverse leakage voltage is the same at point a and point b. Similarly, the gate G of the second MOS tube shows a high level at point b, and the second MOS tube is in the cut-off state. The reverse current cannot flow into the input terminal X, thereby achieving the purpose of preventing reverse flow. In addition, if the leakage voltage at point a is to be loaded to the input terminal X, the leakage voltage must break through the cut-off second MOS tube Q11 to enter the input terminal X, but the breakdown voltage and current of the MOS tube are extremely large, and the internal resistance when cut off is infinite, which is in a high-resistance state and is impossible to reversely break down. Therefore, the second MOS tube Q11 can achieve the purpose of isolating the reverse current, which has great safety, and reduces power consumption and heat compared to diodes.
[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.
Claims
1. Anti-backflow circuit, characterized in that, The anti-backflow circuit includes: An input terminal for inputting voltage to the rear end; An output terminal for outputting voltage; A control module for sending control signals; A switch unit connected to the control module, configured to receive the control signal and be in a conducting or off state under the control of the control signal, and then output a switch signal; An anti-backflow module connected to the input terminal, the output terminal, and the switch unit, including at least one MOS transistor. The anti-backflow module receives the input voltage from the input terminal and sends the output voltage to the output terminal under the control of the switch unit; Wherein, the switch unit controls the anti-backflow module to conduct or cut off; when the anti-backflow circuit is powered off, the switch unit controls the anti-backflow module to cut off, and prevents the output current from flowing back into the input terminal.
2. The anti-backflow circuit according to claim 1, characterized in that, The control module is a single-chip microcomputer. After the anti-backflow circuit is powered off, the control module outputs a control signal with a low level to the switch unit; the switch unit includes an N-type first MOS transistor. The gate of the first MOS transistor is electrically connected to the control module, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the anti-backflow module; when the gate of the first MOS transistor receives the control signal with a low level, the first MOS transistor cuts off, and the switch unit has no output, so that the anti-backflow module stops working.
3. The anti-backflow circuit according to claim 2, characterized in that, The anti-backflow module includes: A P-type second MOS transistor, the drain of the second MOS transistor is connected to the input terminal, and the gate of the second MOS transistor is connected to the drain of the first MOS transistor; A P-type third MOS transistor, the source of the third MOS transistor is connected to the source of the second MOS transistor, the gate of the third MOS transistor is connected to the gate of the second MOS transistor, and the drain of the third MOS transistor is connected to the output terminal; A bias circuit connected between the source and the gate of the second MOS transistor, configured to adjust the voltage between the gate and the source of the second MOS transistor. When the first MOS transistor is conducting, the second MOS transistor is in the leakage current operating range to input voltage to the source of the third MOS transistor.
4. The anti-backflow circuit according to claim 3, wherein, The bias circuit includes: A first resistor, one end of the first resistor is connected to the source of the second MOS transistor, and the other end of the first resistor is electrically connected to the gate of the second MOS transistor; A zener diode, the positive electrode of the zener diode is electrically connected to the gate of the second MOS transistor, and the negative electrode of the zener diode is connected to the source of the second MOS transistor; The voltage of the zener diode makes the voltage between the source and the gate of the second MOS transistor in the leakage current operating range.
5. The anti-backflow circuit according to claim 4, wherein A second resistor is also electrically connected between the bias circuit and the drain of the first MOS transistor; after the anti-backflow circuit is powered on, the control module outputs a control signal with a high level, so that the first MOS transistor conducts; after the first resistor and the second resistor are voltage-divided, the voltage between the source and the gate of the second MOS transistor is in the leakage current operating range.