Passive detection circuit

Abstract

The utility model relates to the technical field of passive detection, and discloses a passive detection circuit. The circuit specifically comprises an input port arranged at an output circuit side; the switching circuit is used for being switched on when the input port inputs a first signal and is also used for being switched off when the input port inputs a second signal; the conversion circuit is used for converting the first signal into a working signal for driving the control unit to make a corresponding action when the first switching circuit is switched on, and is also used for converting the second signal into a fault signal for driving the control unit to make a corresponding action when the first switching circuit is switched off; according to the invention, other electrical equipment such as a relay or a circuit breaker can be detected, and when different voltage signals are input at the input port, the voltage signals can be converted into driving signals which can be identified by a control unit such as an MCU, so that the fault condition of the electrical equipment can be accurately fed back to the control unit.

Description

Technical Field

[0001] This utility model relates to the field of passive detection technology, and more specifically, to a passive detection circuit. Background Technology

[0002] In the field of industrial control, a large number of output circuits are required for switching control and load driving. Among them, the signal measurement of the output circuit of the device under test is usually performed by a passive detection circuit that does not rely on an external power supply. This passive detection circuit mainly relies on the characteristics of the measured signal itself to perform detection and analysis, and feeds back the detection results to the control unit of the device under test.

[0003] In passive detection circuits, the output circuit often uses relays as the switching action actuators. However, as a contact device, the relay is prone to contact jamming, oxidation, and other faults after frequent operation, resulting in a high failure rate and a short service life. Utility Model Content

[0004] This invention provides a passive detection circuit that can overcome some or all of the defects of the prior art.

[0005] To achieve the above objectives, this utility model provides the following technical solution, which includes:

[0006] The input port is located on the output circuit side;

[0007] A switching circuit that is turned on when a first signal is input to the input port and turned off when a second signal is input to the input port;

[0008] The conversion circuit is used to convert the first signal into a working signal for driving the control unit to perform corresponding actions when the first switching circuit is turned on, and also to convert the second signal into a fault signal for driving the control unit to perform corresponding actions when the first switching circuit is turned off.

[0009] Based on the above, it can detect other electrical equipment such as relays or circuit breakers. It can convert different voltage signals into drive signals that can be recognized by control units such as MCUs when different voltage signals are input to the input port, thereby accurately feeding back the fault status of electrical equipment to the control unit. Furthermore, this utility model has the advantages of being contactless, fast-acting, having a large drive current, and not requiring an external power supply, and can be widely used for measurement in different scenarios and with different voltages.

[0010] Preferably, the switching circuit includes a field-effect transistor Q1, the gate and drain of which are connected in parallel to the input port, and the source of which is connected to the switching circuit.

[0011] Based on the above, it is possible to achieve real-time acquisition of voltage signals at the device being tested.

[0012] Preferably, the conversion circuit includes a transistor Q2, the base of which is connected to the source of the field-effect transistor Q1, and the collector of which is used to output the working signal or the fault signal.

[0013] Based on the above, it is possible to better convert the first signal and the second signal at the input port into working signals and fault signals that can be recognized by the control unit and generate corresponding actions.

[0014] Preferably, a voltage divider resistor is provided between the source of the field-effect transistor Q1 and the transistor Q2. Therefore, the base of the transistor Q2 can effectively acquire the signal indicating whether the field-effect transistor Q1 is on or off.

[0015] Preferably, the conversion circuit includes a power supply VDD located at the collector of the transistor Q2, and a pull-up resistor R5 located between the collector of the transistor Q2 and the power supply VDD. Therefore, it can effectively convert the on / off state transition of the first switching circuit into working signals and fault signals that can be recognized and acted upon by the control unit.

[0016] Preferably, a current-limiting resistor R1 is connected in parallel between the gate and drain of the field-effect transistor Q1, thus providing better current-limiting protection for the field-effect transistor Q1.

[0017] Preferably, a current-limiting resistor R4 is connected in series with the base of the transistor Q2. Therefore, current-limiting protection for the transistor Q2 can be effectively achieved.

[0018] Preferably, the drain of the field-effect transistor Q1 is also connected to a power supply VCC, and the source of the field-effect transistor Q1 is grounded through a voltage divider resistor. Therefore, it is possible to provide a power supply so that an electrical signal capable of driving the transistor Q2 to conduct can be output through the voltage divider resistor.

[0019] Preferably, a protection device D2 is connected in parallel between the gate and drain of the field-effect transistor Q1. This further protects the gate and drain of the field-effect transistor Q1.

[0020] Preferably, the input port is also equipped with an anti-reverse diode D1 and a port protection device D3. This helps to protect the input port. Attached Figure Description

[0021] Figure 1 This is a flowchart of a passive detection circuit according to Example 1;

[0022] Figure 2 This is a circuit diagram of a passive detection circuit in Example 1. Detailed Implementation

[0023] To further understand the content of this utility model, a detailed description of the utility model is provided in conjunction with the embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the utility model.

[0024] Example 1

[0025] Industrial control systems require numerous output circuits for switching control and load driving, typically employing relays as the switching actuators. However, relays, being contact devices, are prone to contact jamming and oxidation after frequent operation, resulting in a high failure rate and short service life. Therefore, there is an urgent need for a switching device or circuit with fast response and low failure rate.

[0026] Therefore, as Figure 1-2 As shown, this embodiment provides flowcharts and circuit diagrams that can solve one or more defects of the prior art described above;

[0027] This embodiment first provides a flowchart of a passive detection circuit to outline the working principle of the circuit diagram in this embodiment. After the input signal from the electrical equipment side enters the circuit, it is initially processed by a passive device (MOSFET). Here, the MOSFET mainly utilizes its own conduction characteristics to transmit the input signal to the subsequent circuit. The control unit receives the signal processed by the MOSFET and performs judgment and analysis based on the characteristics of the signal (such as high and low levels). This process includes the implementation of logical processing or protection functions for the signal.

[0028] like Figure 2 As shown, this embodiment specifically provides a circuit that can solve one or more defects of the prior art, namely a passive detection circuit, which includes:

[0029] The input ports are located on the output circuit side, including DI_1 and DI_2;

[0030] A switching circuit that is turned on when a first signal is input to the input port and turned off when a second signal is input to the input port;

[0031] The conversion circuit is used to convert the first signal into a working signal for driving the control unit to perform corresponding actions when the first switching circuit is turned on, and also to convert the second signal into a fault signal for driving the control unit to perform corresponding actions when the first switching circuit is turned off.

[0032] Based on the above, it can detect other electrical equipment such as relays or circuit breakers. It can convert different voltage signals into drive signals that can be recognized by control units such as MCUs when different voltage signals are input to the input port, thereby accurately feeding back the fault status of electrical equipment to the control unit. Furthermore, this utility model has the advantages of being contactless, fast-acting, having a large drive current, and not requiring an external power supply, and can be widely used for measurement in different scenarios and with different voltages.

[0033] In this embodiment, the switching circuit includes a field-effect transistor Q1, the gate and drain of the field-effect transistor Q1 are connected in parallel to the input port, and the source of the field-effect transistor Q1 is connected to the switching circuit. The field-effect transistor Q1 can be a MOS transistor.

[0034] Based on the above, it is possible to achieve real-time acquisition of voltage signals at the device being tested.

[0035] In this embodiment, the conversion circuit includes a transistor Q2, the base of which is connected to the source of the field-effect transistor Q1, and the collector of which is used to output the working signal or the fault signal.

[0036] Based on the above, it is possible to better convert the first signal and the second signal at the input port into working signals and fault signals that can be recognized by the control unit and generate corresponding actions.

[0037] In this embodiment, a voltage divider resistor is also provided between the source of the field-effect transistor Q1 and the transistor Q2. Therefore, the base of the transistor Q2 can better acquire the signal indicating whether the field-effect transistor Q1 is on or off.

[0038] In this embodiment, the conversion circuit includes a power supply VDD located at the collector of the transistor Q2, and a pull-up resistor R5 located between the collector of the transistor Q2 and the power supply VDD. Therefore, it can effectively convert the on / off state transition of the first switching circuit into working signals and fault signals that can be recognized and acted upon by the control unit.

[0039] In this embodiment, a current-limiting resistor R1 is connected in parallel between the gate and drain of the field-effect transistor Q1, thus achieving better current-limiting protection for the field-effect transistor Q1.

[0040] In this embodiment, a current-limiting resistor R4 is connected in series with the base of the transistor Q2. Therefore, current-limiting protection for the transistor Q2 can be effectively achieved.

[0041] In this embodiment, the drain of the field-effect transistor Q1 is also connected to a power supply VCC, and the source of the field-effect transistor Q1 is grounded through a voltage divider resistor. Therefore, it is possible to provide power so that an electrical signal capable of driving the transistor Q2 to conduct can be output through the voltage divider resistor.

[0042] In this embodiment, a protection device D2 is connected in parallel between the gate and drain of the field-effect transistor Q1. This further protects the gate and drain of the field-effect transistor Q1.

[0043] In this embodiment, an anti-reverse diode D1 and a port protection device D3 are also provided at the input port. This helps to protect the input port.

[0044] The operation process of a passive detection circuit in this embodiment when the input port DI_2 has different voltage levels is as follows:

[0045] a. When the input port DI_2 level changes from high to low or is shorted to ground, the voltage across the current limiting resistor R1 is greater than the Vgs voltage (i.e., the voltage between the gate G and source S of the field-effect transistor Q1), and the field-effect transistor Q1 is turned on, which is equivalent to the switch being closed. At this moment, VCC is turned on through the field-effect transistor Q1 to the voltage divider resistors R2 and R3, causing the transistor Q2 to turn on. The control unit detects the level changing from high to low, and after judging and analyzing the characteristics of the signal, it issues a corresponding protection command.

[0046] b. When the input port DI_2 level changes from low to high or the external wiring harness is disconnected, the voltage across the current limiting resistor R1 is less than Vgs, the field-effect transistor Q1 turns on and turns off, which is equivalent to the switch being turned off. At this moment, the drain voltage of the field-effect transistor Q1 is 0V, and the voltage after the voltage division by resistors R2 and R3 cannot cause the transistor Q2 to turn on. The control unit detects the level changing from low to high, and after judging and analyzing the characteristics of the signal, it issues a corresponding protection command.

[0047] If the control unit detects a low-level active signal: the DI_2 port signal is low, the field-effect transistor Q1 is turned on, and the control unit detects a low level continuously, meaning the device under test on the input port side is working normally; otherwise, it indicates a device malfunction.

[0048] The main advantages of the passive detection circuit in this embodiment are its simple structure, low cost, and lack of need for an additional power supply. This makes it very useful in many low-power, cost-sensitive applications. Furthermore, since its conversion circuit can convert a large voltage input signal into a drive signal that can be recognized by the control unit, it has a wide detection range and is applicable to a wide range of scenarios.

[0049] It is readily understood that those skilled in the art can combine, split, or reorganize the embodiments provided in this application to obtain other embodiments, all of which do not exceed the protection scope of this application.

[0050] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the embodiments shown are only part of the embodiments of the present invention. The actual structure is not limited to this. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A passive detection circuit, characterized in that, include: The input port is located on the output circuit side; A switching circuit that is turned on when a first signal is input to the input port and turned off when a second signal is input to the input port; The conversion circuit is used to convert the first signal into a working signal for driving the control unit to perform corresponding actions when the first switching circuit is turned on, and also to convert the second signal into a fault signal for driving the control unit to perform corresponding actions when the first switching circuit is turned off.

2. The passive detection circuit according to claim 1, characterized in that: The switching circuit includes a field-effect transistor Q1, the gate and drain of which are connected in parallel to the input port, and the source of which is connected to the switching circuit.

3. The passive detection circuit according to claim 2, characterized in that: The conversion circuit includes a transistor Q2, the base of which is connected to the source of the field-effect transistor Q1, and the collector of which is used to output the working signal or the fault signal.

4. The passive detection circuit according to claim 3, characterized in that: A voltage divider resistor is also provided between the source of the field-effect transistor Q1 and the transistor Q2.

5. A passive detection circuit according to claim 3, characterized in that: The conversion circuit includes a power supply VDD located at the collector of the transistor Q2, and a pull-up resistor R5 located between the collector of the transistor Q2 and the power supply VDD.

6. A passive detection circuit according to claim 3, characterized in that: A current-limiting resistor R1 is also connected in parallel between the gate and drain of the field-effect transistor Q1.

7. A passive detection circuit according to claim 3, characterized in that: A current-limiting resistor R4 is also connected in series with the base of the transistor Q2.

8. A passive detection circuit according to claim 4, characterized in that: The drain of the field-effect transistor Q1 is also connected to a power supply VCC, and the source of the field-effect transistor Q1 is grounded through a voltage divider resistor.

9. A passive detection circuit according to claim 4, characterized in that: A protection device D2 is also connected in parallel between the gate and drain of the field-effect transistor Q1.

10. A passive detection circuit according to claim 1, characterized in that: The input port is also equipped with an anti-reverse diode D1 and a port protection device D3.

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