Reverse connection prevention circuit and chip

Abstract

The utility model discloses an anti-reverse connection circuit and a chip. The anti-reverse connection circuit comprises an input port, an output port, a first diode, a first switch tube and a control unit. The anode of the first diode is connected with the input port, the cathode of the diode is connected with the output port, the first end of the first switch tube is connected with the input port, the second end of the first switch tube is connected with ground voltage, and the control unit is connected with the input port and the control end of the first switch tube. The control unit is used for adjusting the voltage on the control end of the first switch tube based on the input voltage. According to the anti-reverse connection circuit and the chip of the utility model, through the arrangement of the control unit, the first switching tube can be turned on when the input voltage is less than a design value of normal work, and the current is discharged with relatively low input impedance, so that mistaken turn-on of a rear-end circuit caused by electric leakage due to faults of a front-end circuit is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of protection circuits, and in particular relates to an anti-reverse connection circuit and a chip. Background Art

[0002] In the existing anti-reverse connection circuit, a diode is generally connected in series between the input port and the output port, and the diode is used to cut off the reverse phase to prevent the reverse current from damaging the circuit. A filter resistor is also set between the input port and the ground voltage. The resistor is used to prevent electromagnetic interference from entering the subsequent circuit. Its resistance value is relatively large and can be designed to be about 10kΩ, so that the circuit avoids excessive current loss at the input port during normal operation.

[0003] When the front-end circuit fails, such as when water enters the switch, the input port may leak even when the circuit is closed. The leakage voltage is generally lower than the design value of the input voltage, but because the filter resistor is too large, it cannot pull down the input voltage, so the back-end circuit may be mistakenly turned on.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0005] The utility model aims to provide an anti-reverse connection circuit and a chip, which can solve the problem of erroneous start-up of the back-end circuit due to leakage current of the input port.

[0006] In order to achieve the above-mentioned purpose, a specific embodiment of the utility model provides an anti-reverse connection circuit, including an input port, an output port, a first diode, a first switch tube and a control unit, wherein the anode of the first diode is connected to the input port, the cathode of the diode is connected to the output port, the first end of the first switch tube is connected to the input port, the second end of the first switch tube is connected to the ground voltage, the control unit is connected to the input port and the control end of the first switch tube, and the control unit is used to adjust the voltage on the control end of the first switch tube based on the input voltage.

[0007] In one or more embodiments of the present utility model, the control unit includes a first resistor, a second resistor, a third resistor and a second switch tube, the first end of the first resistor and the first end of the second resistor are connected to the input port, the second end of the second resistor and the first end of the third resistor are connected to the control end of the second switch tube, the second end of the first resistor and the first end of the second switch tube are connected to the control end of the first switch tube, and the second end of the second switch tube and the second end of the third resistor are connected to the ground voltage.

[0008] In one or more embodiments of the present invention, the control unit further includes a first capacitor, a first end of the first capacitor is connected to the control end of the second switch tube, and a second end of the first capacitor is connected to the ground voltage.

[0009] In one or more embodiments of the present invention, the anti-reverse connection circuit also includes a first filtering unit and / or a second filtering unit, the first filtering unit is connected to the input port to filter the input voltage, and the second filtering unit is connected to the control end of the first switching tube to filter the voltage on the control end of the first switching tube.

[0010] In one or more embodiments of the present invention, the first filtering unit includes a first voltage regulator tube and / or a second capacitor, and one end of the first voltage regulator tube and the second capacitor are connected to the input port and the other end is connected to the ground voltage.

[0011] In one or more embodiments of the present invention, the first voltage regulator is a TVS diode.

[0012] In one or more embodiments of the present invention, the second filtering unit includes one or more of a third capacitor, a fourth resistor and a second voltage-stabilizing tube, and one end of the third capacitor, the fourth resistor and the second voltage-stabilizing tube are connected to the control end of the first switching tube and the other end is connected to the ground voltage.

[0013] In one or more embodiments of the present invention, the anti-reverse connection circuit further includes a second diode, an anode of the second diode is connected to the second end of the first switch tube, and a cathode of the second diode is connected to the ground voltage.

[0014] In one or more embodiments of the present invention, the anti-reverse connection circuit further includes one or more fifth resistors, a first end of the fifth resistor is connected to the input port, and a second end of the fifth resistor is connected to the first end of the first switch tube.

[0015] A specific embodiment of the utility model further provides a chip, comprising the above-mentioned anti-reverse connection circuit.

[0016] Compared with the prior art, the anti-reverse connection circuit and chip of the utility model can turn on the first switch tube and discharge current with a lower input impedance when the input voltage is lower than the design value for normal operation by setting a control unit, thereby avoiding leakage caused by front-end circuit failure and causing the back-end circuit to be mistakenly turned on. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 The figure is a circuit schematic diagram of an anti-reverse connection circuit in one embodiment of the utility model. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] The words "coupled" or "connected" or "connected" in the specification include both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches and follower circuits. In addition, in the present utility model, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.

[0021] like Figure 1 As shown, the anti-reverse connection circuit in one embodiment of the utility model includes an input port V_IN, an output port V_OUT, a first diode D1, a first switch tube Q1, a control unit 10, a first filter unit 20, a second filter unit 30, a fifth resistor R5 and a second diode D2.

[0022] The first filtering unit 20 is connected to the input port V_IN to filter the input voltage to prevent electromagnetic interference from entering the subsequent circuit.

[0023] Specifically, the first filtering unit 20 includes a first voltage regulator tube TVS1 and a second capacitor C2, the first end of the first voltage regulator tube TVS1 and the first end of the second capacitor C2 are connected to the input port V_IN, and the second end of the first voltage regulator tube TVS1 and the second end of the second capacitor C2 are connected to the ground voltage GND.

[0024] Preferably, the first voltage regulator tube TVS1 is a TVS diode, and the first voltage regulator tube TVS1 provides protection when a surge voltage appears at the input port V_IN.

[0025] The anode of the first diode D1 is connected to the input port V_IN, and the cathode of the first diode D1 is connected to the output port V_OUT. The first diode D1 has a reverse connection protection function. When the circuit is reversely connected, the first diode D1 is reversely cut off to prevent the reverse current from damaging the front-end circuit.

[0026] The first end of the fifth resistor R5 is connected to the input port V_IN, the second end of the fifth resistor R5 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the ground voltage GND, the second end of the first switch tube Q1 is connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the ground voltage GND. The second diode D2 is used to prevent the second end of the first switch tube Q1 from receiving reverse current. The control unit 10 is connected to the input port V_IN and the control end of the first switch tube Q1, and the control unit 10 is used to adjust the voltage on the control end of the first switch tube Q1 based on the input voltage. The second filtering unit 30 is connected to the control end of the first switch tube Q1 to filter the voltage on the control end of the first switch tube Q1.

[0027] In one embodiment, two fifth resistors R5 are provided. In other embodiments, one or more fifth resistors R5 may also be provided.

[0028] In one embodiment, the first switch tube Q1 is an NPN MOS tube, the first end of the first switch tube Q1 is a drain, the second end is a source, and the control end is a gate. In other embodiments, the first switch tube Q1 can also be a PNP MOS tube or other devices, and the connection method thereof is adaptively modified.

[0029] like Figure 1 As shown, the control unit 10 includes a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, and a second switch tube Q2. The first end of the first resistor R1 and the first end of the second resistor R2 are connected to the input port V_IN, the second end of the second resistor R2, the first end of the third resistor R3, and the first end of the first capacitor C1 are connected to the control end of the second switch tube Q2, the second end of the first resistor R1 and the first end of the second switch tube Q2 are connected to the control end of the first switch tube Q1, and the second end of the second switch tube Q2, the second end of the third resistor R3, and the second end of the first capacitor C1 are connected to the ground voltage GND.

[0030] In one embodiment, the second switch tube Q2 is an NPN transistor, the first end of the second switch tube Q2 is a collector, the second end is an emitter, and the control end is a base. In other embodiments, the second switch tube Q2 can also be a PNP transistor or other devices, and its connection method is adaptively modified.

[0031] like Figure 1 As shown, the second filtering unit 30 includes a third capacitor C3, a fourth resistor R4, and a second voltage regulator ZD1. The first end of the third capacitor C3, the first end of the fourth resistor R4, and the cathode of the second voltage regulator ZD1 are connected to the control end of the first switch tube Q1, and the second end of the third capacitor C3, the second end of the fourth resistor R4, and the anode of the second voltage regulator ZD1 are connected to the ground voltage GND.

[0032] In one embodiment, the input voltage of the front-end circuit is 9-16V when it works normally. When a fault occurs, the front-end circuit is turned off but a leakage voltage is generated, and the input voltage is reduced to below 9V, which is usually far less than 9V. The resistance values ​​of the first resistor R1 and the second resistor R2 are both 10kΩ, the resistance values ​​of the third resistor R3 and the fourth resistor R4 are both 1kΩ, and the resistance values ​​of the two fifth resistors R5 are both 510Ω.

[0033] When the front-end circuit works normally, taking the input voltage as 9V as an example, through the voltage division of the first resistor R1 and the third resistor R3, the voltage on the control end of the second switch tube Q2 is 0.81V, the second switch tube Q2 is turned on, and the voltage on the control end of the first switch tube Q1 is pulled down to the ground voltage GND, and the first switch tube Q1 is turned off. At this time, the impedance of the input end is the sum of the resistance values ​​of the first resistor R1 and the third resistor R3, 11kΩ.

[0034] When the front-end circuit fails, taking the input voltage dropping to 5V as an example, the voltage on the control end of the second switch tube Q2 is 0.45V, and the second switch tube Q2 cannot be fully turned on. The voltage on the control end of the first switch tube Q1 is higher than the voltage on the second end, and the first switch tube Q1 is turned on. Ignoring the internal resistance of the first switch tube Q1 and the second diode D2, the impedance of the input end is approximately the parallel impedance of the fifth resistor R5, 255Ω. Compared with normal operation, the input end impedance is greatly reduced at this time, so that the leakage current of the input end can pass through the fifth resistor R5 to the first switch tube Q1, and then be discharged to the ground voltage GND through the second diode D2, thereby pulling down the output end voltage to prevent the back-end circuit from being turned on by mistake.

[0035] In other embodiments, the resistance values ​​of the first resistor R1 , the second resistor R2 , the third resistor R3 , the fourth resistor R4 , and the fifth resistor R5 can be adjusted according to actual conditions.

[0036] In other embodiments, one or more of the first filter unit 20, the second filter unit 30, the first capacitor C1 and the second diode D2 may not be provided. Only the first voltage regulator tube TVS1 or the second capacitor C2 may be provided in the first filter unit 20. Only one or two of the third capacitor C3, the fourth resistor R4 and the second voltage regulator tube ZD1 may be provided in the second filter unit 30.

[0037] An embodiment of the present invention further provides a chip, comprising the above-mentioned anti-reverse connection circuit.

[0038] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A reverse connection protection circuit, characterized in that: The device comprises an input port, an output port, a first diode, a first switch tube and a control unit, wherein the anode of the first diode is connected to the input port, the cathode of the diode is connected to the output port, the first end of the first switch tube is connected to the input port, the second end of the first switch tube is connected to the ground voltage, the control unit is connected to the input port and the control end of the first switch tube, and the control unit is used to adjust the voltage on the control end of the first switch tube based on the input voltage.

2. The anti-reverse connection circuit according to claim 1, characterized in that: The control unit includes a first resistor, a second resistor, a third resistor and a second switch tube. The first end of the first resistor and the first end of the second resistor are connected to the input port, the second end of the second resistor and the first end of the third resistor are connected to the control end of the second switch tube, the second end of the first resistor and the first end of the second switch tube are connected to the control end of the first switch tube, and the second end of the second switch tube and the second end of the third resistor are connected to the ground voltage.

3. The anti-reverse connection circuit according to claim 2, characterized in that: The control unit further includes a first capacitor, a first end of the first capacitor is connected to the control end of the second switch tube, and a second end of the first capacitor is connected to the ground voltage.

4. The anti-reverse connection circuit according to claim 1, characterized in that: The anti-reverse connection circuit also includes a first filtering unit and / or a second filtering unit, the first filtering unit is connected to the input port to filter the input voltage, and the second filtering unit is connected to the control end of the first switching tube to filter the voltage on the control end of the first switching tube.

5. The anti-reverse connection circuit according to claim 4, characterized in that: The first filtering unit includes a first voltage regulator tube and / or a second capacitor. One end of the first voltage regulator tube and the second capacitor are connected to the input port and the other end is connected to the ground voltage.

6. The anti-reverse connection circuit according to claim 5, characterized in that: The first voltage regulator is a TVS diode.

7. The anti-reverse connection circuit according to claim 4, characterized in that: The second filtering unit includes one or more of a third capacitor, a fourth resistor and a second voltage regulator tube, wherein one end of the third capacitor, the fourth resistor and the second voltage regulator tube are connected to the control end of the first switch tube and the other end is connected to the ground voltage.

8. The anti-reverse connection circuit according to claim 1, characterized in that: The reverse connection prevention circuit further includes a second diode, an anode of the second diode is connected to the second end of the first switch tube, and a cathode of the second diode is connected to the ground voltage.

9. The anti-reverse connection circuit according to claim 1, characterized in that: The anti-reverse connection circuit further includes one or more fifth resistors, a first end of the fifth resistor is connected to the input port, and a second end of the fifth resistor is connected to the first end of the first switch tube.

10. A chip, characterized in that: The invention comprises the anti-reverse connection circuit as claimed in any one of claims 1 to 9.

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