Current-limiting protection circuit based on MOS tube

Abstract

The utility model discloses a current-limiting protection circuit based on an MOS tube, and specifically relates to the technical field of current-limiting protection. The circuit is technically characterized by comprising a first resistor, a first triode, an MOS tube, a second resistor and a third resistor, a current detection module formed by a first resistor is used for measuring the current value of an input signal and converting the current signal into a voltage signal, and a first triode is switched on after the measured current value reaches a preset current threshold value; a feedback circuit module composed of a first triode, a second resistor and a third resistor is used for controlling the grid electrode of the MOS tube to discharge through the first triode so as to control the voltage of the grid electrode of the MOS tube to be reduced and the equivalent resistance between the drain electrode and the source electrode to be increased, so that the current of the drain electrode is reduced, and the voltage of the first resistor can be reduced immediately after reduction; therefore, negative feedback dynamic balance is formed between the first triode and the MOS tube, and the circuit always operates at a stable current value.

Description

Technical Field

[0001] The utility model relates to the technical field of current limiting protection, in particular to a current limiting protection circuit based on a MOS tube. Background Art

[0002] In industrial control and automation systems, analog input and output devices are an important part of industrial control systems. Various process variables (such as temperature, pressure, flow, etc.) need to be detected and controlled. These process variables are usually analog signals and need to be read and controlled by analog input and output devices.

[0003] Various distributed IO modules, PLCs, and other industrial process controllers need to collect various external analog signals, such as temperature, pressure, flow, etc., and convert them into digital signals through the digital-to-analog converter, or convert digital signals into analog signals for output. This allows the signals to be processed by other signal systems, thereby achieving process control and detection, such as controlling the operation of frequency converters, actuators, or motors.

[0004] With the further development of industrial automation systems, the performance and functions of analog input and output devices are constantly improving. For example, analog input and output devices can adopt higher resolution, larger sampling rate and wider input range to improve their measurement accuracy and application scope.

[0005] However, in the prior art, analog current input and output devices do not control the loop current and often operate in an out-of-range current range. The analog current input and output circuits are prone to overload or short circuit, thereby causing damage to the device equipment. At the same time, the analog current input and output circuits have poor anti-interference capabilities, making it difficult to operate normally under EMC interference and unable to filter abnormal input and output signals well.

[0006] Therefore, the utility model aims to provide a current limiting protection circuit based on MOS tube to solve the above-mentioned related problems. Utility Model Content

[0007] The technical problem to be solved by the utility model is that in the prior art, the analog current input and output device does not control the loop current, often operates in the current out-of-range range, and the analog current input and output circuit is prone to overload or short circuit, thereby causing damage to the device and equipment. The purpose is to provide a current limiting protection circuit based on MOS tube, through a current detection module composed of a first resistor to measure the current value of an input signal and convert the current signal into a voltage signal, when the measured current value reaches a preset current threshold, the first triode will be turned on; then the feedback circuit module composed of the first triode, the second resistor and the third resistor controls the gate of the MOS tube to discharge through the first triode, so as to control the gate voltage of the MOS tube to drop, the equivalent resistance between the drain and the source increases, so that the drain current decreases, and after the decrease, the first resistor will immediately decrease, so that a negative feedback dynamic balance is formed between the first triode and the MOS tube, so that the circuit always maintains a stable current value operation, thereby preventing the analog current input and output circuit from being overloaded or short-circuited when operating in the out-of-range current range, causing damage to the device and equipment.

[0008] The utility model is realized by the following technical solutions:

[0009] A current limiting protection circuit based on a MOS tube, the current limiting protection circuit comprising a first resistor, a first triode, a MOS tube, a second resistor and a third resistor, the current limiting protection circuit is provided with a first port and a second port, the input end of the first resistor is connected to the first port, and the output end of the first resistor is connected to the source of the MOS tube;

[0010] The emitter of the first triode is connected to the input end of the first resistor, the base of the first triode is connected to the output end of the first resistor, the collector of the first triode is connected to the gate of the MOS tube; the drain of the MOS tube is connected to the second port;

[0011] An input end of the second resistor is connected to the first port, and an output end of the second resistor is connected to an input end of the third resistor;

[0012] The input end of the third resistor is also connected to the collector of the first transistor, and the output end of the third resistor is grounded.

[0013] Furthermore, the current limiting protection circuit also includes a first protection device and a second protection device, the input end of the first protection device is connected to the first port, and the output end of the first protection device is connected to the input end of the second resistor;

[0014] One end of the second protection device is connected to the output end of the first protection device, and the other end of the second protection device is grounded.

[0015] Furthermore, the current limiting protection circuit also includes a first protection device and a second protection device, the input end of the first protection device is connected to the second port, and the output end of the first protection device is connected to the drain of the MOS tube;

[0016] One end of the second protection device is connected to the output end of the first protection device, and the other end of the second protection device is grounded.

[0017] Furthermore, the current limiting protection circuit also includes a third protection device, one end of the third protection device is connected to the source of the MOS tube, and the other end of the third protection device is connected to the gate of the MOS tube.

[0018] Furthermore, the current limiting protection circuit also includes a fourth protection device, one end of the fourth protection device is connected to the source of the MOS tube, and the other end of the fourth protection device is connected to the gate of the MOS tube.

[0019] Furthermore, the current limiting protection circuit further includes a first capacitor and a fourth resistor, one end of the first capacitor is connected to the source of the MOS tube, and the other end of the first capacitor is connected to one end of the fourth resistor;

[0020] The other end of the fourth resistor is connected to the drain of the MOS tube.

[0021] Furthermore, the first protection device is a fuse.

[0022] Furthermore, the second protection device is a first diode.

[0023] Furthermore, the third protection device is a second capacitor.

[0024] Furthermore, the fourth protection device is a second diode.

[0025] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0026] 1. In the utility model, a current detection module formed by a first resistor is used to measure the current value of an input signal and convert the current signal into a voltage signal. When the measured current value reaches a preset current threshold, the first triode will be turned on; and then a feedback circuit module formed by the first triode, a second resistor and a third resistor controls the gate of the MOS tube to discharge through the first triode, so as to control the gate voltage of the MOS tube to drop, increase the equivalent resistance between the drain and the source, and reduce the drain current. After the drop, the voltage of the first resistor will drop immediately, so that a dynamic balance of negative feedback is formed between the first triode and the MOS tube, so that the circuit always runs at a stable current value, thereby preventing the analog current input and output circuit from being overloaded or short-circuited when running in an out-of-range current range, causing damage to the device equipment.

[0027] 2. In the utility model, by adopting a current limiting protection circuit based on a MOS tube, the current can be effectively limited to ensure that the current runs within a safe range. By adjusting the conduction state of the MOS tube, the current limiting protection circuit can control the current in the input or output circuit to prevent overload or short circuit, thereby protecting the system and equipment from damage; at the same time, by adopting a current limiting protection circuit based on a MOS tube, precise control of the current can be achieved, so that the system can operate according to predetermined requirements. Through the cooperation of the current sensor and the feedback circuit, the current limiting protection circuit can monitor the current changes in real time, and adjust the MOS tube as needed to keep the current stable at a set level.

[0028] 3. In the utility model, based on the low on-resistance and fast switching speed of the MOS tube, the current limiting protection circuit can achieve lower power consumption when working, which helps to improve the energy efficiency of the system and reduce energy consumption; based on the fast response speed of the MOS tube, the current limiting protection circuit can quickly respond to current changes and realize dynamic adjustment, which makes the current limiting protection circuit suitable for industrial control systems with high current requirements, and can respond to changes and demands in the process in a timely manner.

[0029] 4. In the present invention, multiple protection devices are used to ensure that the MOS tube operates stably under different environmental conditions, and to protect the system and equipment from external interference, thereby improving the reliability and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present utility model, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present utility model, and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0031] Figure 1 This is a circuit connection diagram of a current limiting protection circuit based on a MOS tube in this embodiment;

[0032] Figure 2 This is a circuit connection diagram in which a protection unit in a current limiting protection circuit based on a MOS tube is connected to an input port side in this embodiment;

[0033] Figure 3 The following is a circuit connection diagram of a protection unit connected to the output port side in a current limiting protection circuit based on a MOS tube in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other embodiments, in order to avoid confusing the present invention, well-known structures, circuits, materials or methods are not specifically described.

[0035] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] In the description of the present invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0037] Example

[0038] See also Figure 1 As shown, this embodiment shows a current limiting protection circuit based on a MOS tube, the current limiting protection circuit includes a first resistor R24, a first triode Q19, a MOS tube Q8, a second resistor R25 and a third resistor R27, and the current limiting protection circuit is provided with a first port and a second port; the input end of the first resistor R24 ​​is connected to the first port, and the output end of the first resistor R24 ​​is connected to the source of the MOS tube Q8; the emitter of the first triode Q19 is connected to the input end of the first resistor R24, the base of the first triode Q19 is connected to the output end of the first resistor R24, and the collector of the first triode Q19 is connected to the gate of the MOS tube Q8; the drain of the MOS tube Q8 is connected to the second port; the input end of the second resistor R25 is connected to the first port, and the output end of the second resistor R25 is connected to the input end of the third resistor R27; the input end of the third resistor R27 is also connected to the collector of the first triode Q19, and the output end of the third resistor R27 is grounded.

[0039] Specifically, in this embodiment, the first port is the input port of the current limiting protection circuit, and the second port is the output port of the current limiting protection circuit.

[0040] At the same time, in the present embodiment, a current detection sensor is formed by the first resistor R24 ​​to measure the current value of the input signal and convert the current signal into a voltage signal. When the measured current value reaches a preset current threshold (the voltage value is about 0.7V), the first transistor Q19 will be turned on; and then the feedback circuit module formed by the first transistor Q19, the second resistor R25 and the third resistor R27 controls the gate of the MOS tube Q8 to discharge through the first transistor Q19, so as to control the gate voltage of the MOS tube Q8 to decrease, and the equivalent resistance between the drain and the source increases, so that the drain current decreases. After the decrease, the voltage of the first resistor R24 ​​will decrease immediately, so that a negative feedback dynamic balance is formed between the first transistor Q19 and the MOS tube Q8, so as to ensure that the system can stably operate below 25mA under different load working conditions, and effectively protect the system and equipment from the influence of overload or short circuit.

[0041] See also Figure 2 As shown, in another embodiment, the current limiting protection circuit also includes a first protection device F2 and a second protection device D11, the first protection device F2 is a fuse, the second protection device D11 is a first diode, the first diode is a transient suppression diode, the input end of the first protection device F2 is connected to the first port, and the output end of the first protection device F2 is connected to the input end of the second resistor R25; one end of the second protection device D11 is connected to the output end of the first protection device F2, and the other end of the second protection device D11 is grounded.

[0042] Specifically, in this embodiment, the first protection device F2 and the second protection device D11 are connected to the input port, and a protection unit is formed by the first protection device F2 and the second protection device D11. The protection unit filters surges and electrostatic pulses generated by external port access, as well as large short-circuit currents. The first protection device F2 is an overcurrent protection part, specifically a fuse. When the current of the circuit exceeds the expected limit, that is, when it is detected that the loop current exceeds the safety range of 0.5A, it will respond and cut off the circuit, cut off the abnormal state in the backflow, so as to prevent damage to the system and equipment. The second protection device D11 is a pulse protection part, specifically a transient suppression diode. When the circuit is in a normal state, there are large-energy pulses under different environments or interferences. The second protection device D11 can absorb the high pulse voltage of the input signal to keep the input signal within an acceptable range, thereby preventing damage to the subsequent current limiting protection circuit.

[0043] See also Figure 3As shown, in another embodiment, the current limiting protection circuit also includes a first protection device F2 and a second protection device D11. The first protection device F2 is a fuse, and the second protection device D11 is a first diode, which is a transient suppression diode. The input end of the first protection device F2 is connected to the second port, and the output end of the first protection device F2 is connected to the drain of the MOS tube Q8; one end of the second protection device D11 is connected to the output end of the fuse, and the other end of the second protection device D11 is grounded.

[0044] Specifically, in this embodiment, the working principle and effect of the current limiting protection circuit are consistent with those of the above embodiment, except that the first protection device F2 and the second protection device D11 are connected to the output port.

[0045] In another embodiment, the current limiting protection circuit further includes a third protection device C10, which is a second capacitor, one end of the third protection device C10 is connected to the source of the MOS tube Q8, and the other end of the third protection device C10 is connected to the gate of the MOS tube Q8.

[0046] Specifically, in this embodiment, the third protection device C10 is specifically a capacitor, which further prevents the pulse voltage at the input end from impacting the source and gate of the MOS tube Q8.

[0047] In another embodiment, the current limiting protection circuit further includes a fourth protection device D10, which is a second diode, one end of which is connected to the source of the MOS tube Q8, and the other end of which is connected to the gate of the MOS tube Q8.

[0048] Specifically, in this embodiment, the fourth protection device D10 is specifically a diode, which stabilizes the voltage between the source and the gate to be within the safe operating range of the MOS tube Q8.

[0049] In another embodiment, the current limiting protection circuit further includes a first capacitor C9 and a fourth resistor R23, one end of the first capacitor C9 is connected to the source of the MOS tube Q8, and the other end of the first capacitor C9 is connected to one end of the fourth resistor R23; the other end of the fourth resistor R23 is connected to the drain of the MOS tube Q8.

[0050] Specifically, in this embodiment, the first capacitor C9 and the fourth resistor R23 are used to prevent the pulse voltage at the input end from impacting the source and drain of the MOS tube Q8.

[0051] Working process: When external current flows in through the input port or when current is output through the output port, the first protection device can timely detect whether the current exceeds the safety range of 0.5A, and respond to overcurrent protection according to whether the current exceeds the safety range. If it does not exceed the safety range, it enters the current limiting protection circuit, and the second protection device will absorb the high pulse voltage of the input signal to prevent damage to the current limiting protection circuit;

[0052] When the current passes through the first resistor R24, the current detection sensor formed by the first resistor R24 ​​measures the current value of the input signal and converts the current signal into a voltage signal. When the measured current value reaches the preset current threshold, the first transistor Q19 will be turned on, and then the feedback circuit module formed by the first transistor Q19, the second resistor R25 and the third resistor R27 controls the gate of the MOS tube Q8 to discharge through the first transistor Q19, so as to control the gate voltage of the MOS tube Q8 to decrease, increase the equivalent resistance between the drain and the source, and reduce the drain current, thereby achieving the purpose of current limiting output; after the decrease, the voltage of the first resistor R24 ​​will immediately decrease, so that a dynamic balance of negative feedback is formed between the first transistor Q19 and the MOS tube Q8.

[0053] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only the specific implementation method of the utility model and is not used to limit the protection scope of the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A current limiting protection circuit based on MOS tube, characterized in that: The current limiting protection circuit includes a first resistor, a first triode, a MOS tube, a second resistor and a third resistor. The current limiting protection circuit is provided with a first port and a second port. The input end of the first resistor is connected to the first port, and the output end of the first resistor is connected to the source of the MOS tube. The emitter of the first triode is connected to the input end of the first resistor, the base of the first triode is connected to the output end of the first resistor, the collector of the first triode is connected to the gate of the MOS tube; the drain of the MOS tube is connected to the second port; An input end of the second resistor is connected to the first port, and an output end of the second resistor is connected to an input end of the third resistor; The input end of the third resistor is also connected to the collector of the first transistor, and the output end of the third resistor is grounded.

2. A current limiting protection circuit based on a MOS tube according to claim 1, characterized in that: The current limiting protection circuit also includes a first protection device and a second protection device, the input end of the first protection device is connected to the first port, and the output end of the first protection device is connected to the input end of the second resistor; One end of the second protection device is connected to the output end of the first protection device, and the other end of the second protection device is grounded.

3. The current limiting protection circuit based on MOS tube according to claim 1, characterized in that: The current limiting protection circuit also includes a first protection device and a second protection device, the input end of the first protection device is connected to the second port, and the output end of the first protection device is connected to the drain of the MOS tube; One end of the second protection device is connected to the output end of the first protection device, and the other end of the second protection device is grounded.

4. The current limiting protection circuit based on MOS tube according to claim 1, characterized in that: The current limiting protection circuit also includes a third protection device, one end of the third protection device is connected to the source of the MOS tube, and the other end of the third protection device is connected to the gate of the MOS tube.

5. The current limiting protection circuit based on MOS tube according to claim 1, characterized in that: The current limiting protection circuit also includes a fourth protection device, one end of which is connected to the source of the MOS tube, and the other end of which is connected to the gate of the MOS tube.

6. The current limiting protection circuit based on MOS tube according to claim 1, characterized in that: The current limiting protection circuit also includes a first capacitor and a fourth resistor, one end of the first capacitor is connected to the source of the MOS tube, and the other end of the first capacitor is connected to one end of the fourth resistor; The other end of the fourth resistor is connected to the drain of the MOS tube.

7. A current limiting protection circuit based on a MOS tube according to any one of claims 2 to 3, characterized in that: The first protection device is a fuse.

8. A current limiting protection circuit based on a MOS tube according to any one of claims 2 to 3, characterized in that: The second protection device is a first diode.

9. The current limiting protection circuit based on MOS tube according to claim 4, characterized in that: The third protection device is a second capacitor.

10. The current limiting protection circuit based on MOS tube according to claim 5, characterized in that: The fourth protection device is a second diode.

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