Sensor output reverse connection prevention circuit and sensor

Abstract

The utility model provides a kind of sensor output anti-reverse connection circuit, including first switching circuit, second switching circuit, third switching circuit, fourth switching circuit, stabilivolt diode and general diode;In the utility model, when sensor error wiring, first terminal connects sensor signal output, second terminal connects internal sensor chip power supply, third terminal connects internal sensor chip signal output, fourth terminal connects external power supply anode, due to power supply connection is not normal, internal sensor chip cannot be normally powered, second terminal cannot drive second switching circuit conduction, second switching circuit is closed, so that first switching circuit is closed, the source electrode voltage of fourth switching circuit is 9V~36V, the gate electrode voltage of fourth switching circuit is 0V, fourth switching circuit cannot be conducted, to reach the goal of output reverse connection protection.

Description

Technical Field

[0001] This utility model belongs to the field of electrical control technology, specifically relating to a sensor output reverse connection protection circuit and sensor. Background Technology

[0002] Sensors typically use three pins for output: positive power, negative power, and signal output. Under normal wiring conditions, the sensor can work normally. However, in actual use, there may be situations where incorrect pin connections can damage the sensor. Since sensors are usually quite expensive, this can result in significant economic losses.

[0003] Most methods for implementing reverse connection protection for sensor outputs involve adding a reverse connection protection diode. When the positive terminal of the power supply is connected to the sensor signal output pin, the diode's unidirectional conduction and reverse cutoff characteristics are used to prevent power supply voltage from entering the circuit through the signal output pin and damaging it.

[0004] However, when the diode is forward-biased, a junction voltage exists, resulting in a voltage drop of 0.2V to 0.7V, which distorts the sensor output signal. Therefore, a novel reverse polarity protection circuit for the sensor output needs to be designed to solve the current technical problem. Utility Model Content

[0005] To address the shortcomings of existing technologies, this invention provides a sensor output reverse connection protection circuit and sensor that achieves reverse connection protection when the positive terminal of the power supply is mistakenly connected to the sensor output pin.

[0006] The technical solution of this utility model is as follows: a sensor output reverse connection protection circuit, including a first switching circuit, a second switching circuit, a third switching circuit, a fourth switching circuit, a Zener diode, and a general-purpose diode; the transmitter of the first switching circuit is connected to a first terminal; the base terminal and the transmitter of the first switching circuit are both connected to the collector terminal of the second switching circuit through a second resistor; the collector terminal of the first switching circuit is connected to the gate terminal of the third switching circuit and the gate terminal of the fourth switching circuit through a third resistor; the base terminal of the second switching circuit is connected to a second terminal; the transmitter of the second switching circuit is connected to the negative terminal of the power supply; the drain terminal of the third switching circuit is connected to a third terminal; the source terminal of the third switching circuit is connected to the source terminal of the fourth switching circuit; the drain terminal of the fourth switching circuit is connected to a fourth terminal; the cathode of the Zener diode is connected between the gate terminal of the third switching circuit and the gate terminal of the fourth switching circuit; the anode of the Zener diode is connected to the anode of the general-purpose diode; and the cathode of the general-purpose diode is connected to the negative terminal of the power supply.

[0007] Furthermore, the first switching circuit has a first transistor, and a first resistor is connected between the emitter and the base of the first transistor.

[0008] Furthermore, the second switching circuit has a second transistor, a sixth resistor is connected between the emitter and the base of the second transistor, and a fifth resistor is connected between the base of the second transistor and the second terminal.

[0009] Furthermore, the third switching circuit has a first field-effect transistor.

[0010] Furthermore, the fourth switching circuit has a second field-effect transistor, and a fourth resistor is connected between the gate of the second field-effect transistor and the source of the second field-effect transistor.

[0011] The sensor has a reverse connection protection circuit for the sensor output as described in any of the preceding items.

[0012] The beneficial effects of this utility model are as follows: In this utility model, when the sensor is incorrectly wired, the first terminal is connected to the sensor signal output, the second terminal is connected to the power supply of the internal sensor chip, the third terminal is connected to the signal output of the internal sensor chip, and the fourth terminal is connected to the positive terminal of the external power supply. Due to the abnormal power supply wiring, the internal sensor chip cannot be powered normally, the second terminal cannot drive the second switch circuit to conduct, the second switch circuit is closed, and the first switch circuit is closed. The source terminal voltage of the fourth switch circuit is 9V~36V, the gate terminal voltage of the fourth switch circuit is 0V, and the fourth switch circuit cannot conduct, thereby achieving the goal of output reverse connection protection. Attached Figure Description

[0013] Figure 1 This is a circuit diagram of the reverse connection protection circuit for the sensor output in this utility model. Detailed Implementation

[0014] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are not intended to limit the present invention or its application or use in any way. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present invention thorough and complete, and to fully express the scope of the present invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0015] The terms "first," "second," and similar words used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as "including" or "comprising" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0016] like Figure 1 As shown, the sensor output reverse connection protection circuit includes a first switching circuit, a second switching circuit, a third switching circuit, a fourth switching circuit, a Zener diode, and a general-purpose diode. The emitter of the first switching circuit is connected to a first terminal J1. The base and emitter of the first switching circuit are both connected to the collector of the second switching circuit via a second resistor R2. The collector of the first switching circuit is connected to the gate of the third switching circuit and the gate of the fourth switching circuit via a third resistor R3. The base of the second switching circuit is connected to a second terminal J2, and the emitter of the second switching circuit is connected to the negative terminal of the power supply. The drain of the third switching circuit is connected to a third terminal J3, and the source of the third switching circuit is connected to the source of the fourth switching circuit. The drain of the fourth switching circuit is connected to a fourth terminal J4. The cathode of the Zener diode D1 is connected between the gate of the third switching circuit and the gate of the fourth switching circuit. The anode of the Zener diode D1 is connected to the anode of the general-purpose diode D2, and the cathode of the general-purpose diode D2 is connected to the negative terminal of the power supply.

[0017] In the above embodiment, when the sensor is properly wired, the first terminal J1 is connected to a 9V~36V power supply, the second terminal J2 is connected to the power supply of the internal sensor chip, the third terminal J3 is connected to the signal output of the internal sensor chip, and the maximum signal output voltage must be at least 4V lower than the power supply voltage. The fourth terminal J4 is connected to the sensor's external output signal interface. When the internal sensor chip is powered normally, the second switch circuit is turned on through the second terminal J2. After the second switch circuit is turned on, the first switch circuit is turned on. The external power supply voltage flows through the first terminal J1 and the first switch circuit, through the third resistor R3. The third resistor R3 limits the current and divides the voltage. The gate voltage of the Zener diode D1, the third switch circuit, and the fourth switch circuit is always less than 16V. The general-purpose diode D2 prevents reverse connection of the power supply. After the Zener diode D1 regulates the voltage, the sensor drives the second switch circuit. When the third and fourth switch circuits are turned on, the internal sensor chip output signal is output to the fourth terminal J4 through the third terminal J3, the third switch circuit, and the fourth switch circuit. When the sensor is incorrectly wired, the first terminal J1 is connected to the sensor signal output, the second terminal J2 is connected to the power supply of the internal sensor chip, the third terminal J3 is connected to the signal output of the internal sensor chip, and the fourth terminal J4 is connected to the positive terminal of the external power supply. Due to the abnormal power supply wiring, the internal sensor chip cannot be powered normally, the second terminal J2 cannot drive the second switch circuit to turn on, the second switch circuit is turned off, causing the first switch circuit to turn off. The source terminal voltage of the fourth switch circuit is 9V~36V, and the gate terminal voltage of the fourth switch circuit is 0V. The fourth switch circuit cannot be turned on, thus achieving the goal of output reverse connection protection.

[0018] In the above embodiments, the sensor output signal voltage and the sensor power supply voltage should meet the following requirements: the maximum output voltage of the sensor output signal + 4V ≤ the minimum power supply voltage of the sensor.

[0019] As one specific implementation of the first switching circuit, the first switching circuit has a first transistor Q1, and a first resistor R1 is connected between the emitter and the base of the first transistor Q1; specifically, the first transistor Q1 is a PNP transistor.

[0020] As one specific implementation of the second switching circuit, the second switching circuit has a second transistor Q3, a sixth resistor R6 is connected between the emitter and the base of the second transistor Q3, and a fifth resistor R5 is connected between the base of the second transistor Q3 and the second terminal J2; specifically, the second transistor is an NPN transistor.

[0021] As one specific implementation of the third switching circuit, the third switching circuit has a first field-effect transistor Q4.

[0022] As one specific implementation of the fourth switching circuit, the fourth switching circuit has a second field-effect transistor Q2, and a fourth resistor R4 is connected between the gate of the second field-effect transistor Q2 and the source of the second field-effect transistor Q2.

[0023] Furthermore, when the sensor is properly wired, the first terminal J1 is connected to a 9V~36V power supply, the second terminal J2 is connected to the power supply of the internal sensor chip, the third terminal J3 is connected to the signal output of the internal sensor chip, and the maximum voltage of the output signal must be at least 4V lower than the power supply voltage. The fourth terminal J4 is connected to the sensor's external output signal interface. When the internal sensor chip is powered normally, the second transistor Q3 is driven to conduct through the second terminal J2. After the second transistor Q3 conducts, the first resistor R1 and the second resistor R2 divide the voltage, causing the first diode Q1 to conduct. The third resistor R3 limits the current and divides the voltage, and the Zener diode D1 regulates the voltage, ensuring that the gate voltages of the second field-effect transistor Q2 and the fourth field-effect transistor Q4 are always less than 16V. D2 prevents reverse connection of the power supply. After the Zener diode D1 regulates the voltage, it drives the second field-effect transistor Q2 and the fourth field-effect transistor Q4 to conduct. Thus, the output signal of the internal sensor chip is output to the fourth terminal J4 through the third terminal J3, the fourth field-effect transistor Q4, and the second field-effect transistor Q2.

[0024] In some embodiments, a sensor is disclosed having a sensor output reverse connection protection circuit as in any of the preceding embodiments.

[0025] The various embodiments of this utility model have now been described in detail. To avoid obscuring the concept of this utility model, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0026] The embodiments described above only illustrate some implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A sensor output reverse connection protection circuit, characterized in that: The system includes a first switching circuit, a second switching circuit, a third switching circuit, a fourth switching circuit, a Zener diode, and a general-purpose diode. The emitter of the first switching circuit is connected to a first terminal. Both the base and emitter of the first switching circuit are connected to the collector of the second switching circuit via a second resistor. The collector of the first switching circuit is connected to the gate of the third switching circuit and the gate of the fourth switching circuit via a third resistor. The base of the second switching circuit is connected to a second terminal, and the emitter of the second switching circuit is connected to the negative terminal of a power supply. The drain of the third switching circuit is connected to a third terminal, and the source of the third switching circuit is connected to the source of the fourth switching circuit. The drain of the fourth switching circuit is connected to a fourth terminal. The cathode of the Zener diode is connected between the gates of the third and fourth switching circuits. The anode of the Zener diode is connected to the anode of the general-purpose diode, and the cathode of the general-purpose diode is connected to the negative terminal of a power supply.

2. The sensor output reverse connection protection circuit according to claim 1, characterized in that: The first switching circuit has a first transistor, and a first resistor is connected between the emitter and the base of the first transistor.

3. The sensor output reverse connection protection circuit according to claim 1, characterized in that: The second switching circuit has a second transistor, a sixth resistor is connected between the emitter and the base of the second transistor, and a fifth resistor is connected between the base of the second transistor and the second terminal.

4. The sensor output reverse connection protection circuit according to claim 1, characterized in that: The third switching circuit has a first field-effect transistor.

5. The sensor output reverse connection protection circuit according to claim 1, characterized in that: The fourth switching circuit has a second field-effect transistor, and a fourth resistor is connected between the gate of the second field-effect transistor and the source of the second field-effect transistor.

6. A sensor, characterized in that: It has a sensor output reverse connection protection circuit as described in any one of claims 1 to 5.

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