Reverse connection prevention circuit with backward flow prevention function

Abstract

The utility model provides an anti-reverse connection circuit with an anti-backflow function, which comprises a first field effect transistor and a second field effect transistor, the first field effect transistor is provided with a first drain electrode, a first source electrode and a first grid electrode, the first drain electrode is connected with a power supply input end, and a first body diode is arranged between the first drain electrode and the first source electrode; the second field effect transistor is provided with a second drain electrode, a second source electrode and a second grid electrode, the second source electrode is connected with the first source electrode, the second drain electrode is connected with the power supply output end, and a second body diode is arranged between the second drain electrode and the second source electrode; wherein the negative electrode of the first body diode is connected with the first source electrode, and the negative electrode of the second body diode is connected with the second source electrode; when the anti-reverse-connection circuit is positively connected, the first field effect transistor and the second field effect transistor are opened; and when the anti-reverse-connection circuit is reversely connected, the first field effect transistor and the second field effect transistor are cut off. The technical problem that in the prior art, centralized power supply is needed to improve the overall efficiency of the vehicle lamp, and reverse leakage current flows back to the input end to trigger other function signals by mistake is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply, and in particular to an anti-reverse connection circuit with an anti-backflow function. Background Art

[0002] In the existing electronic circuit system, it often happens that users connect the power supply with the wrong polarity. In the lightest case, the system fails to start up, and in the worst case, the entire system is burned out, resulting in immeasurable losses.

[0003] When designing and developing automotive parts products, power supply anti-reverse connection is usually considered. The anti-reverse connection performance of products is also a common requirement of each vehicle factory for automotive electronic products. With the development of vehicle lights towards the direction of multi-pixels, the overall power of the whole lamp has increased significantly compared with before, and the heat has also increased significantly. The requirement for the power supply efficiency of the whole lamp has been significantly improved, and the anti-reverse connection efficiency is more stringent than before.

[0004] However, in the actual use process, there is such a problem: At present, the method to improve the overall efficiency of vehicle lights is to centrally supply power to each function (such as position, braking, and steering) through an anti-reverse connection and place them in a DC-DC converter. This centralized power supply will cause the reverse leakage current to flow back to the input end and accidentally trigger other function signals. Summary of the Utility Model

[0005] The utility model solves the technical problem in the prior art that in order to improve the overall efficiency of vehicle lights, centralized power supply is required, which will cause the reverse leakage current to flow back to the input end and accidentally trigger other function signals.

[0006] To solve the above problems, the utility model provides an anti-reverse connection circuit with an anti-backflow function, including: a first field-effect transistor, which has a first drain, a first source, and a first gate. The first drain is connected to the power input end, and a first body diode is provided between the first drain and the first source; a second field-effect transistor, which has a second drain, a second source, and a second gate. The second source is connected to the first source, the second drain is connected to the power output end, and a second body diode is provided between the second drain and the second source; wherein, the negative electrode of the first body diode is connected to the first source, and the negative electrode of the second body diode is connected to the second source; when the anti-reverse connection circuit is connected correctly, the first field-effect transistor and the second field-effect transistor are turned on; when the anti-reverse connection circuit is connected reversely, the first field-effect transistor and the second field-effect transistor are turned off.

[0007] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The power input terminal is connected to an external power supply. When the power supply polarity is correctly connected (that is, the reverse connection prevention circuit is correctly connected), both the first field effect transistor and the second field effect transistor are turned on and conducting. As a result, a normal voltage is output at the power output terminal, and then the input voltage is supplied to the output voltage through the first field effect transistor and the second field effect transistor. When the power supply polarity is incorrectly connected (that is, the reverse connection prevention circuit is reversely connected), both the first field effect transistor and the second field effect transistor are cut off and disconnected. Therefore, the input voltage and the output voltage do not interfere with each other. And because the body diodes of the first field effect transistor and the second field effect transistor, namely the first body diode and the second body diode, are reversely connected in series, when one body diode is conducting, the other body diode is reversely cut off. Therefore, the phenomenon of voltage and current backflow to the power input terminal can be avoided, thus realizing the function of preventing current backflow. At the same time, compared with the traditional Schottky diode reverse connection prevention circuit, the reverse leakage current of the dual field effect transistor is much lower than that of a single Schottky diode.

[0008] In an example of the present utility model, the reverse connection prevention circuit further includes: a third field effect transistor, which has a third drain, a third source, and a third gate. The third gate is connected to the power input terminal, the third drain is connected to the first gate and the second gate, and the third source is grounded. Among them, when the reverse connection prevention circuit is correctly connected, the third field effect transistor is turned on; when the reverse connection prevention circuit is reversely connected, the third field effect transistor is cut off.

[0009] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The conduction state of the third field effect transistor can be controlled according to the connection state of the reverse connection prevention circuit, so as to control the conduction states of the first field effect transistor and the second field effect transistor through the conduction state of the third field effect transistor. When the reverse connection prevention circuit is correctly connected, the third field effect transistor is turned on and conducting. At this time, the first gate and the second gate are at a low level, and both the first field effect transistor and the second field effect transistor are turned on and conducting. When the reverse connection prevention circuit is reversely connected, the third field effect transistor is cut off and disconnected. At this time, the first gate and the second gate are at a high level, and both the first field effect transistor and the second field effect transistor are cut off and disconnected. The third field effect transistor is set instead of a triode or a diode because the field effect transistor has a faster conduction rate and a high switching frequency. Another point is that the field effect transistor is voltage-driven, with lower steady-state drive power consumption, a controllable trigger threshold, and higher anti-interference ability than the current-driven triode.

[0010] In an example of the present utility model, the reverse connection prevention circuit further includes: a first zener diode, one end of which is connected between the first field effect transistor and the second field effect transistor, and the other end is connected to the third drain.

[0011] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The first zener diode is used to protect the first field-effect transistor and the second field-effect transistor, preventing the high voltage on the first gate and the second gate from damaging the first field-effect transistor and the second field-effect transistor.

[0012] In an example of the present utility model, the reverse connection prevention circuit further includes: a first capacitor, which is connected in parallel across both ends of the first zener diode; a first resistor, which is connected in parallel across both ends of the first zener diode.

[0013] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The first capacitor and the first resistor form a first RC low-pass filter circuit, which can effectively filter out high-frequency current signals. The first resistor is a voltage-dividing resistor and is also used for voltage division.

[0014] In an example of the present utility model, the reverse connection prevention circuit further includes: a second resistor, which is connected between the first gate and the third drain; a fourth resistor, which is connected between the power input terminal and the third gate.

[0015] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The second resistor and the fourth resistor are voltage-dividing resistors.

[0016] In an example of the present utility model, the reverse connection prevention circuit further includes: a second zener diode, one end of which is connected between the fourth resistor and the third gate, and the other end of which is grounded; a second capacitor, which is connected in parallel across both ends of the second zener diode; a third resistor, which is connected in parallel across both ends of the second zener diode.

[0017] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The second zener diode is used to protect the third field-effect transistor, preventing the high voltage on the third gate from damaging the third field-effect transistor; the second capacitor and the third resistor form a second RC low-pass filter circuit, which can effectively filter out high-frequency current signals. The third resistor is a voltage-dividing resistor and is also used for voltage division.

[0018] In an example of the present utility model, the third field-effect transistor is an NMOS transistor.

[0019] In an example of the present utility model, the first field-effect transistor and the second field-effect transistor are PMOS transistors.

[0020] In an example of the present utility model, the reverse connection prevention circuit further includes: a first diode, the positive electrode of which is connected to the power input terminal.

[0021] Compared with the prior art, the technical effects achieved by adopting this technical solution are as follows: The first diode is arranged in the reverse connection prevention circuit to isolate the signal link and the power link.

[0022] After adopting the technical solution of the present utility model, the following technical effects can be achieved:

[0023] (1) When the power supply polarity is connected abnormally (that is, the reverse connection protection circuit is reversely connected), both the first field effect transistor and the second field effect transistor are cut off and disconnected. Therefore, the input voltage and the output voltage do not interfere with each other. And because the body diodes of the first field effect transistor and the second field effect transistor, namely the first body diode and the second body diode, are reversely connected in series, when one body diode is conducting, the other body diode is reversely cut off. Therefore, the phenomenon that the voltage and current flow back to the power input end can be avoided, thus realizing the function of preventing current backflow;

[0024] (2) The conduction state of the third field effect transistor can be controlled according to the connection state of the reverse connection protection circuit, so as to control the conduction states of the first field effect transistor and the second field effect transistor through the conduction state of the third field effect transistor;

[0025] (3) The third field effect transistor is set instead of a triode or a diode because the field effect transistor has a faster conduction rate and a higher switching frequency; another point is that the field effect transistor is voltage-driven, with lower steady-state drive power consumption, a controllable trigger threshold, and a higher anti-interference ability than the current-driven triode. Description of the Drawings

[0026] Figure 1 FIG. is a circuit schematic diagram of a reverse connection protection circuit with an anti-backflow function provided in Embodiment 1 of the present utility model. Detailed Embodiments

[0027] In order to make the above objects, features and advantages of the present utility model more obvious and understandable, the technical solutions in the embodiments of the present utility model are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0028]

Embodiment 1

[0029] See Figure 1, the present utility model provides an anti-reverse connection circuit with an anti-backflow function, including: a first field-effect transistor Q1 and a second field-effect transistor Q2. The first field-effect transistor Q1 is provided with a first drain, a first source, and a first gate. The first drain is connected to the power input terminal, and a first body diode is provided between the first drain and the first source; the second field-effect transistor Q2 is provided with a second drain, a second source, and a second gate. The second source is connected to the first source, the second drain is connected to the power output terminal, and a second body diode is provided between the second drain and the second source; wherein, the negative electrode of the first body diode is connected to the first source, and the negative electrode of the second body diode is connected to the second source; when the anti-reverse connection circuit is connected correctly, the first field-effect transistor Q1 and the second field-effect transistor Q2 are turned on; when the anti-reverse connection circuit is connected reversely, the first field-effect transistor Q1 and the second field-effect transistor Q2 are turned off.

[0030] In a specific embodiment, the power input terminal is connected to an external power supply. When the power supply polarity is connected correctly (that is, the anti-reverse connection circuit is connected correctly), both the first field-effect transistor Q1 and the second field-effect transistor Q2 are turned on and conducting. Then, a normal voltage is output at the power output terminal, and the input voltage is supplied to the output voltage through the first field-effect transistor Q1 and the second field-effect transistor Q2; when the power supply polarity is connected incorrectly (that is, the anti-reverse connection circuit is connected reversely), both the first field-effect transistor Q1 and the second field-effect transistor Q2 are turned off and disconnected. Therefore, the input voltage and the output voltage do not interfere with each other. And because the body diodes of the first field-effect transistor Q1 and the second field-effect transistor Q2, namely the first body diode and the second body diode, are connected in reverse series, when one body diode is conducting, the other body diode is reversely turned off. Therefore, the phenomenon of voltage and current backflow to the power input terminal can be avoided, thus realizing the function of preventing current backflow. At the same time, compared with the traditional Schottky diode anti-reverse connection circuit, the reverse leakage current of the dual field-effect transistors is much lower than that of a single Schottky diode.

[0031] Furthermore, the anti-reverse connection circuit further includes: a third field-effect transistor Q3. The third field-effect transistor Q3 is provided with a third drain, a third source, and a third gate. The third gate is connected to the power input terminal, the third drain is connected to the first gate and the second gate, and the third source is grounded; wherein, when the anti-reverse connection circuit is connected correctly, the third field-effect transistor Q3 is turned on; when the anti-reverse connection circuit is connected reversely, the third field-effect transistor Q3 is turned off.

[0032] Specifically, the conduction state of the third field-effect transistor Q3 can be controlled according to the connection state of the reverse connection prevention circuit, so as to control the conduction states of the first field-effect transistor Q1 and the second field-effect transistor Q2 through the conduction state of the third field-effect transistor Q3; when the reverse connection prevention circuit is correctly connected, the third field-effect transistor Q3 is turned on and conducts, at this time the first gate and the second gate are at low level, and both the first field-effect transistor Q1 and the second field-effect transistor Q2 are turned on and conduct; when the reverse connection prevention circuit is reversely connected, the third field-effect transistor Q3 is cut off and disconnected, at this time the first gate and the second gate are at high level, and both the first field-effect transistor Q1 and the second field-effect transistor Q2 are cut off and disconnected. The third field-effect transistor Q3 is set instead of a triode or a diode because the field-effect transistor has a faster conduction rate and a high switching frequency; another point is that the field-effect transistor is voltage-driven, with lower steady-state drive power consumption, a controllable trigger threshold, and higher anti-interference ability than the current-driven triode.

[0033] Further, the reverse connection prevention circuit further includes: a first voltage stabilizing diode ZD1, one end of the first voltage stabilizing diode ZD1 is connected between the first field-effect transistor Q1 and the second field-effect transistor Q2, and the other end of the first voltage stabilizing diode ZD1 is connected to the third drain.

[0034] Specifically, the first voltage stabilizing diode ZD1 is used to protect the first field-effect transistor Q1 and the second field-effect transistor Q2, and prevent the high voltage on the first gate and the second gate from damaging the first field-effect transistor Q1 and the second field-effect transistor Q2. Preferably, the first voltage stabilizing diode ZD1 is recommended to use BZT52C5V1.

[0035] Further, the reverse connection prevention circuit further includes: a first capacitor C1 and a first resistor R1, the first capacitor C1 is connected in parallel across both ends of the first voltage stabilizing diode ZD1; the first resistor R1 is connected in parallel across both ends of the first voltage stabilizing diode ZD1.

[0036] Specifically, the first capacitor C1 and the first resistor R1 form a first RC low-pass filter circuit, which can effectively filter out high-frequency current signals, and the first resistor R1 is a voltage-dividing resistor and is also used for voltage division. Preferably, the first capacitor C1 is recommended to use a 10nF C0603 capacitor, and the first resistor R1 is recommended to use a 47kΩ R0603 resistor.

[0037] Further, the reverse connection prevention circuit further includes: a second resistor R2 and a fourth resistor R4, the second resistor R2 is connected between the first gate and the third drain; the fourth resistor R4 is connected to the power input terminal and the third gate.

[0038] Specifically, the second resistor R2 and the fourth resistor R4 are voltage-dividing resistors. Preferably, the second resistor R2 and the fourth resistor R4 are recommended to use 10kΩ R0603 resistors.

[0039] Further, the reverse connection prevention circuit further includes: a second voltage stabilizing diode ZD2, a second capacitor C2, and a third resistor R3. One end of the second voltage stabilizing diode ZD2 is connected between the fourth resistor R4 and the third gate, and the other end of the second voltage stabilizing diode ZD2 is grounded; the second capacitor C2 is connected in parallel across both ends of the second voltage stabilizing diode ZD2; the third resistor R3 is connected in parallel across both ends of the second voltage stabilizing diode ZD2.

[0040] Specifically, the second voltage stabilizing diode ZD2 is used to protect the third field effect transistor Q3 and prevent the high voltage on the third gate from damaging the third field effect transistor Q3; the second capacitor C2 and the third resistor R3 form a second RC low-pass filter circuit, which can effectively filter out high-frequency current signals, and the third resistor R3 is a voltage-dividing resistor and is also used for voltage division. Preferably, the second voltage stabilizing diode ZD2 is recommended to use BZT52C5V1, the second capacitor C2 is recommended to use a 1nF C0603 capacitor, and the third resistor R3 is recommended to use a 47kΩ R0603 resistor.

[0041] Further, the third field effect transistor Q3 is an NMOS transistor.

[0042] Specifically, the third field effect transistor Q3 is recommended to use 2N7002,215, and 2N7002,215 is an N-channel enhancement-mode field effect transistor using trench MOSFET technology.

[0043] Further, the first field effect transistor Q1 and the second field effect transistor Q2 are PMOS transistors.

[0044] Specifically, the first field effect transistor Q1 and the second field effect transistor Q2 are recommended to use DMP6023LE-13.

[0045] Further, the reverse connection prevention circuit further includes: a first diode D1, and the positive electrode of the first diode D1 is connected to the power input terminal.

[0046] Specifically, the first diode D1 is arranged in the reverse connection prevention circuit to isolate the signal link and the power link. Preferably, the first diode D1 is recommended to use 1N4148WS.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A reverse connection prevention circuit with backflow prevention function, characterized in that: The anti-reverse connection circuit comprises: A first field effect transistor, wherein the first field effect transistor is provided with a first drain, a first source and a first gate, the first drain is connected to a power input terminal, and a first body diode is provided between the first drain and the first source; a second field effect transistor, wherein the second field effect transistor is provided with a second drain, a second source and a second gate, the second source is connected to the first source, the second drain is connected to the power output terminal, and a second body diode is provided between the second drain and the second source; Among them, the cathode of the first body diode is connected to the first source, and the cathode of the second body diode is connected to the second source; when the anti-reverse connection circuit is forwardly connected, the first field effect transistor and the second field effect transistor are turned on; when the anti-reverse connection circuit is reversely connected, the first field effect transistor and the second field effect transistor are turned off.

2. The anti-reverse connection circuit according to claim 1, characterized in that: The anti-reverse connection circuit also includes: A third field effect transistor, wherein the third field effect transistor is provided with a third drain, a third source and a third gate, the third gate is connected to the power input terminal, the third drain is connected to the first gate and the second gate, and the third source is grounded; Wherein, when the anti-reverse connection circuit is connected in a forward direction, the third field effect transistor is turned on; when the anti-reverse connection circuit is connected in a reverse direction, the third field effect transistor is turned off.

3. The anti-reverse connection circuit according to claim 2, characterized in that: The anti-reverse connection circuit also includes: A first voltage-stabilizing diode, one end of which is connected between the first field-effect transistor and the second field-effect transistor, and the other end of which is connected to the third drain.

4. The anti-reverse connection circuit according to claim 3, characterized in that: The anti-reverse connection circuit also includes: A first capacitor, wherein the first capacitor is connected in parallel to two ends of the first voltage stabilizing diode; A first resistor is connected in parallel to two ends of the first voltage stabilizing diode.

5. The anti-reverse connection circuit according to claim 2, characterized in that: The anti-reverse connection circuit also includes: a second resistor, the second resistor being connected between the first gate and the third drain; A fourth resistor is connected to the power input terminal and the third gate.

6. The anti-reverse connection circuit according to claim 5, characterized in that: The anti-reverse connection circuit also includes: A second voltage stabilizing diode, one end of the second voltage stabilizing diode is connected between the fourth resistor and the third gate, and the other end of the second voltage stabilizing diode is grounded; a second capacitor, the second capacitor being connected in parallel to two ends of the second voltage zener diode; A third resistor is connected in parallel to two ends of the second voltage stabilizing diode.

7. The anti-reverse connection circuit according to claim 2, characterized in that: The third field effect transistor is an NMOS transistor.

8. The anti-reverse connection circuit according to claim 1, characterized in that: The first field effect transistor and the second field effect transistor are PMOS transistors.

9. The anti-reverse connection circuit according to claim 1, characterized in that: The anti-reverse connection circuit also includes: A first diode, wherein an anode of the first diode is connected to the power input terminal.

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