Current-limiting protection circuit based on MOS tube

Abstract

The utility model relates to the technical field of sampling circuits, in particular to a current-limiting protection circuit based on an MOS (Metal Oxide Semiconductor) tube, which comprises a current sampling module connected in a load loop and used for acquiring load current signals in real time; the input end of the comparison module is connected with the current sampling module, and the comparison module is used for comparing the sampling current with a preset threshold value; the input end of the driving module is connected with the output end of the comparison module, and the output end is connected with the grid of the MOS tube; the MOS tube is connected in series in a load power supply loop, and the conduction state of the MOS tube is controlled by the driving module; the threshold setting module provides an adjustable current threshold reference value for the comparison module, the current sampling module monitors load current in real time and drives an MOS tube to quickly cut off or restore power supply after comparison with a threshold value through a hysteresis comparator, the circuit adopts push-pull driving and grid protection design, the response time is smaller than or equal to 10 microseconds, the adjustable current limiting range of 1A-20A is supported, and the current sampling module is connected with the MOS tube. And the circuit integrates transient suppression and self-recovery functions, is suitable for power adapters, motor controllers and other scenes, and has the advantages of low cost and high reliability.

Description

Technical Field

[0001] This utility model relates to the field of sampling circuit technology, and in particular to a current limiting protection circuit based on a MOS transistor. Background Technology

[0002] In industrial control and automation systems, analog input / output devices (AIPs) are a crucial component of industrial control systems. They are used to detect and control various process variables (such as temperature, pressure, and flow rate). These process variables are typically analog signals, requiring AIPs for reading and control, including various distributed I / O modules, PLCs, and other industrial process controllers. External analog signals, such as temperature, pressure, and flow rate, need to be acquired and converted into digital signals by digital-to-analog converters (DACs), or vice versa. This allows the signals to be processed by other signal systems, enabling process control and monitoring. For example, controlling the operation of frequency converters, actuators, or motors. With the further development of industrial automation systems, the performance and functionality of AIPs are continuously improving. For instance, AIPs can employ higher resolution, larger sampling rates, and wider input ranges to improve measurement accuracy and applicability. However, in current technologies, analog current input / output devices lack loop current control, often operating outside their current range. This makes analog current input / output circuits prone to overload or short circuits, potentially damaging devices; additionally, their response time is relatively slow. Utility Model Content

[0003] The purpose of this invention is to provide a current limiting protection circuit based on a MOSFET to solve the problems existing in the prior art.

[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0005] A current-limiting protection circuit based on a MOSFET, comprising:

[0006] The current sampling module is connected in the load circuit and is used to acquire the load current signal in real time.

[0007] The comparison module, whose input is connected to the current sampling module, is used to compare the sampled current with a preset threshold.

[0008] The driver module has its input terminal connected to the output terminal of the comparator module, and its output terminal connected to the gate of the MOS transistor.

[0009] The MOSFET is connected in series in the load power supply circuit, and its conduction state is controlled by the drive module.

[0010] The threshold setting module provides an adjustable current threshold reference value to the comparison module.

[0011] In a further embodiment, the current sampling module consists of a sampling resistor and a differential amplifier circuit, wherein the sampling resistor is connected in series in the load circuit, and the output of the differential amplifier circuit is connected to the comparison module.

[0012] The sampling resistor has a resistance value of 0.1mΩ-10mΩ and an accuracy of ±1%.

[0013] In a further embodiment, the comparison module employs a hysteresis comparator circuit, which includes an operational amplifier and a positive feedback resistor, with the hysteresis voltage range set to 50mV-200mV.

[0014] The threshold setting module adjusts the reference voltage via a potentiometer or digital potentiometer, with a threshold range covering 1A-20A.

[0015] In a further embodiment, the driving module includes a push-pull amplifier circuit and a gate protection circuit for rapidly switching the on and off states of the MOSFET.

[0016] The gate protection circuit consists of a Zener diode and a current-limiting resistor to prevent the gate-source voltage from exceeding the withstand voltage of the MOSFET.

[0017] In a further embodiment, the MOSFET is an N-channel enhancement-mode power MOSFET, with its drain connected in series in the positive circuit of the load power supply, and its on-resistance ≤5mΩ;

[0018] A transient suppression diode is connected in parallel between the source and drain of the MOS transistor to absorb the reverse electromotive force generated by sudden load changes.

[0019] In a further embodiment, a self-recovery module is also included, which controls the MOSFET to periodically turn on / off when the load current exceeds a threshold until the fault is eliminated.

[0020] In summary, this utility model has the following beneficial effects:

[0021] 1. The current sampling module monitors the load current in real time. After comparing the current with the threshold through the hysteresis comparator, the MOSFET is driven to quickly cut off or restore the power supply. The circuit adopts a push-pull drive and gate protection design, with a response time of ≤10μs. It supports an adjustable current limiting range of 1A to 20A and integrates transient suppression and self-recovery functions. It is suitable for power adapters, motor controllers and other scenarios, and has the advantages of low cost and high reliability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0023] In the diagram, 1 is the current sampling module; 2 is the comparison module; 3 is the drive module; 4 is the MOSFET; 5 is the threshold setting module; and 6 is the self-recovery module. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Identical parts are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to the attached figures. Figure 1 In this specification, the terms "bottom surface" and "top surface," "inner" and "outer" refer to the direction toward or away from the geometry of a specific component. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this specification, "a plurality of" means two or more, unless otherwise explicitly and specifically defined by the direction of the center.

[0026] Example 1:

[0027] like Figure 1 As shown, a current-limiting protection circuit based on a MOSFET includes:

[0028] The current sampling module 1 is connected in the load circuit and is used to acquire the load current signal in real time. The current sampling module 1 consists of a sampling resistor and a differential amplifier circuit. The sampling resistor is connected in series in the load circuit, and the output of the differential amplifier circuit is connected to the comparator module 2. The resistance of the sampling resistor is 0.1mΩ-10mΩ and the accuracy is ±1%.

[0029] Comparison module 2, with its input connected to current sampling module 1, is used to compare the sampled current with a preset threshold. Comparison module 2 adopts a hysteresis comparator circuit, including an operational amplifier, a positive feedback resistor, and the hysteresis voltage range is set to 50mV-200mV. Threshold setting module 5 adjusts the reference voltage through a potentiometer or digital potentiometer, with a threshold range covering 1A-20A.

[0030] The driver module 3 has its input terminal connected to the output terminal of the comparator module 2 and its output terminal connected to the gate of the MOSFET 4. The driver module 3 includes a push-pull amplifier circuit and a gate protection circuit, which are used to quickly switch the conduction and turn-off states of the MOSFET 4. The gate protection circuit consists of a Zener diode and a current-limiting resistor to prevent the gate-source voltage from exceeding the withstand voltage of the MOSFET.

[0031] MOSFET 4 is connected in series in the load power supply circuit. Its conduction state is controlled by the drive module 3. MOSFET 4 is an N-channel enhancement-mode power MOSFET. Its drain is connected in series in the positive terminal circuit of the load power supply. Its on-resistance is ≤5mΩ. A transient suppression diode is connected in parallel between the source and drain of MOSFET 4 to absorb the reverse electromotive force generated by the sudden change in load.

[0032] Threshold setting module 5 provides an adjustable current threshold reference value to comparison module 2;

[0033] When the load current exceeds the threshold, the self-recovery module 6 drives the MOSFET 4 to periodically turn on / off until the fault is eliminated.

[0034] Specific implementation process: The circuit is integrated on the PCB board. In the PCB layout, the current sampling module 1 and the MOSFET 4 are connected in Kelvin to reduce measurement errors.

[0035] In the embodiments disclosed in this utility model, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments disclosed in this utility model according to the specific circumstances.

[0036] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A MOS transistor based current limiting protection circuit, characterized by: The utility model relates to a current sampling module (1) connected to the load circuit for real-time acquisition of load current signal, a comparison module (2) connected to the input of the current sampling module (1) for comparing the sampled current with the preset threshold, a drive module (3) connected to the output of the comparison module (2) and the gate of the MOS tube (4), a MOS tube (4) connected in series in the load power supply circuit, whose conduction state is controlled by the drive module (3), and a threshold setting module (5) providing adjustable current threshold reference value to the comparison module (2). The current sampling module (1) is composed of a sampling resistor and a differential amplifier circuit, the sampling resistor is connected in series in the load circuit, and the differential amplifier circuit is connected to the comparison module (2). The resistance of the sampling resistor is 0.1 mΩ-10 mΩ, and the accuracy is ±1%. The comparison module (2) adopts a hysteresis comparator circuit, including an operational amplifier and a positive feedback resistor, and the hysteresis voltage range is set to 50 mV-200 mV. The threshold setting module (5) adjusts the reference voltage through a potentiometer or a digital potentiometer, and the threshold range covers 1A-20A. The drive module (3) includes a push-pull amplifier circuit and a gate protection circuit for quickly switching the conduction and off state of the MOS tube (4).

2. The current limit protection circuit based on MOS transistor according to claim 1, characterized in that: The gate protection circuit is composed of a voltage stabilizing diode and a current limiting resistor to prevent the gate-source voltage from exceeding the voltage resistance of the MOS tube. The MOS tube (4) is an N-channel enhancement mode power MOSFET, and its drain is connected in series in the load power supply positive circuit, and the conduction resistance is less than or equal to 5 mΩ.

3. The current limit protection circuit based on MOS transistor according to claim 1, characterized in that: A transient suppression diode is connected in parallel between the source and the drain of the MOS tube (4) to absorb the reverse electromotive force generated by the load mutation. The utility model also includes a self-recovery module (6), when the load current exceeds the threshold, the drive module (3) controls the MOS tube (4) to be periodically turned on / off until the fault is eliminated.

4. The current limit protection circuit based on MOS transistor according to claim 1, characterized in that: ​ ​ 5. The MOS-based current limiting protection circuit of claim 1, wherein: ​ ​ 6. The MOS-based current limiting protection circuit of claim 1, wherein: ​

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