Overcurrent protection self-locking circuit
By designing an overcurrent protection self-locking circuit, using the combination of PNP transistor and thyristor, the problem of unstable power output in the prior art is solved, and the self-locking protection and clear working status indication are realized when load current is overloaded, which improves the practicality of the circuit.
Patent Information
- Application Number
- CN202422312688.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2034-09-23
AI Technical Summary
The existing overcurrent protection circuit cannot effectively self-lock when the load current is overloaded, resulting in unstable power output and lack of clear operating status indications, which makes it less practical.
An overcurrent protection self-locking circuit is designed, using the combination of PNP transistor and thyristor, combined with the control of capacitor and resistor, to achieve self-locking protection when the load current exceeds the set value, and prompt the user through the indicator light to ensure the stable power output.
It realizes self-locking protection when load current is overloaded, the power output is stable, and the user is prompted through indicator lights, improving the practicality and reliability of the overcurrent protection circuit.
Smart Images
Figure CN223124586U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an overcurrent protection self-locking circuit. Background Art
[0002] During the operation of a circuit, when a short circuit occurs in the load or the load current exceeds a preset value, it may cause component damage and abnormal operation, or even pose a danger. In response to this situation, when designing a circuit, an overcurrent protection circuit needs to be added between the power output terminal and the load input terminal. The overcurrent protection circuit is used to cut off the power output to prevent damage to the load circuit. Currently, there are various types of overcurrent protection circuit designs. The principle is that during power supply, if the load current exceeds the preset value, a fuse or an electronic switch is used to cut off the power. However, due to the very fast rising speed of the current, the overcurrent protection requires a very fast response speed. Therefore, the method of using an electronic switch as the power switch of the overcurrent protection circuit has become the mainstream.
[0003] A PNP triode and a current detection resistor are used for current detection, and a PMOS transistor is used as the electronic switch. When the load current exceeds the set value, the PNP triode is saturated and turned on, and the PMOS transistor is turned off, thereby cutting off the power output. In actual situations, after the overcurrent protection is triggered, the PMOS transistor is turned off, the power no longer supplies power to the load, no current flows through the current detection resistor, the PNP triode will be turned off, and the PMOS transistor will also be turned on again. Since the load current is still overloaded, the overcurrent protection will be triggered again, and the above process will repeat cyclically, which does not meet the requirement of cutting off the power output when the load current exceeds the preset value, and its practicability is poor.
[0004] Therefore, in view of the above problems, it is necessary to design an overcurrent protection circuit with a self-locking function. Summary of the Utility Model
[0005] The purpose of the utility model is to overcome the deficiencies of the prior art and provide an overcurrent protection self-locking circuit.
[0006] The purpose of the utility model is achieved through the following technical solutions:
[0007] The overcurrent protection self-locking circuit is characterized in that: the emitter of the PNP transistor and the first end of the first resistor are connected to the power supply VCC, the collector of the PNP transistor is connected to the first end of the second resistor and the first end of the fourth resistor, the second end of the second resistor is connected to GND, the base of the PNP transistor is connected to the second end of the first resistor, and is connected to the anode of the thyristor, the first end of the first capacitor and the source of the PMOS tube, the second end of the fourth resistor is connected to the first end of the second capacitor, the first end of the first switch and the control electrode of the thyristor, the second end of the second capacitor is connected to GND, the second end of the first switch is connected to GND, the cathode of the thyristor is connected to the anode of the diode, the cathode of the diode is connected to the second end of the first capacitor, the first end of the third resistor and the gate of the PMOS tube, and the second end of the third resistor is connected to GND.
[0008] Furthermore, in the above-mentioned overcurrent protection self-locking circuit, the cathode of the thyristor is connected to the positive electrode of the indicator light, the negative electrode of the indicator light is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to GND.
[0009] Furthermore, in the above-mentioned overcurrent protection self-locking circuit, the drain of the PMOS tube is connected to the load.
[0010] Furthermore, in the above-mentioned overcurrent protection self-locking circuit, when the load current is less than the set value, the PNP transistor is not turned on, the control electrode potential of the thyristor is pulled down, the thyristor is not turned on, the diode is reversely cut off, the PMOS tube is turned on, and the power supply VCC supplies power to the load; when the load current exceeds the set value, the PNP transistor is saturated and turned on, the control electrode potential of the thyristor is pulled up, and the thyristor is turned on; at the same time, the gate potential of the PMOS tube is pulled up, the PMOS tube is turned off, and the power supply VCC stops supplying power to the load; when the power supply VCC does not supply power to the load, no current flows through the first resistor, the PNP transistor is turned off, the control electrode potential of the thyristor is pulled down, and due to the current limiting of the second resistor and the fourth resistor, the turning off of the PNP transistor cannot turn off the thyristor, and the current flowing through the thyristor is set by the fifth resistor to be greater than its holding current, the thyristor is maintained in the on state, and the PMOS tube is maintained in the off state until the first switch is pressed to release the trigger state.
[0011] Furthermore, in the above-mentioned overcurrent protection self-locking circuit, after the overcurrent protection is triggered, the thyristor is turned on and the indicator light is lit, indicating that the current overcurrent protection circuit is in a triggered state.
[0012] Furthermore, in the above-mentioned overcurrent protection self-locking circuit, the diode is used to control the current path of the first capacitor during the soft-start charging process of the PMOS tube.
[0013] Compared with the prior art, the utility model has significant advantages and beneficial effects, which are specifically embodied in the following aspects:
[0014] The overcurrent protection circuit of the present utility model has a self-locking function. When the load current exceeds the set value, the overcurrent protection circuit will be triggered, the power output will be cut off, and the indicator light will be lit to prompt the user that the load current is overloaded. The overcurrent protection circuit maintains the triggered state until the user manually releases it. The overcurrent protection trigger indicator light facilitates the user to understand the working state of the overcurrent protection circuit, making the overcurrent protection circuit have better practicability.
[0015] Other features and advantages of the present utility model will be described in the subsequent specification, and in part, will become apparent from the specification, or can be understood by implementing the specific embodiments of the present utility model. The objectives and other advantages of the present utility model can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings. Brief Description of the Drawings
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present utility model, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.
[0017] Figure 1 : Schematic circuit diagram of the present utility model. Detailed Description of the Specific Embodiments
[0018] The following will combine the drawings in the embodiments of the present utility model to clearly and completely describe the technical solutions in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Usually, the components of the embodiments of the present utility model described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the drawings is not intended to limit the scope of the present utility model to be protected, but only represents the selected embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.
[0019] It should be noted that: similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present utility model, orientation terms and order terms are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.
[0020] Such as Figure 1As shown, in the over-current protection self-locking circuit, the emitter of the PNP transistor Q1 and the first end of the first resistor R1 are connected to the power supply VCC, the collector of the PNP transistor Q1 is connected to the first end of the second resistor R2 and the first end of the fourth resistor R4, the second end of the second resistor R2 is connected to GND, the base of the PNP transistor Q1 is connected to the second end of the first resistor R1, and is connected to the anode of the thyristor Q3, the first end of the first capacitor C1 and the source of the PMOS tube Q2, and the second end of the fourth resistor R4 is connected to the first end of the second capacitor C2, the first end of the first switch K1 and the thyristor Q 3, the second end of the second capacitor C2 is connected to GND, the second end of the first switch K1 is connected to GND, the cathode of the thyristor Q3 is connected to the positive electrode of the indicator light LED1, the negative electrode of the indicator light LED1 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is connected to GND; the cathode of the thyristor Q3 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the second end of the first capacitor C1 and the first end of the third resistor R3 and the gate of the PMOS tube Q2, and the second end of the third resistor R3 is connected to GND; the drain of the PMOS tube Q2 is connected to the load L.
[0021] The thyristor Q3 is a self-locking switch, the fourth resistor R4 and the second capacitor C2 are used to reduce the sensitivity of the overcurrent protection circuit, the indicator LED1 is used for overcurrent protection indication, the fifth resistor R5 is used to set the holding current of the thyristor, the diode D1 is used to control the current path of the first capacitor C1 during the soft start charging process (only flows through the third resistor R3), and the first switch K1 is a reset switch for releasing the circuit overcurrent protection state.
[0022] When the load current is less than the set value, the PNP transistor Q1 is not turned on, the control electrode potential of the thyristor Q3 is pulled down, the thyristor Q3 is not turned on, the diode D1 is reversely cut off, the PMOS tube Q2 is turned on, and the power supply VCC supplies power to the load; when the load current exceeds the set value, the PNP transistor Q1 is saturated and turned on, the control electrode potential of the thyristor Q3 is pulled up, the thyristor Q3 is turned on, and the indicator LED1 is lit, indicating that the current overcurrent protection circuit is in the triggered state; at the same time, the gate potential of the PMOS tube Q2 is pulled up, the PMOS tube Q2 is turned off, and the power supply VCC Stop supplying power to the load; when the power supply VCC does not supply power to the load, since the power supply VCC stops supplying power to the load, no current flows through the first resistor R1, the PNP transistor Q1 is turned off, and the control electrode potential of the thyristor Q3 is pulled down. Due to the current limiting of the second resistor R2 and the fourth resistor R4, the turning off of the PNP transistor Q1 cannot turn off the thyristor Q3. The current flowing through the thyristor Q3 is set to be greater than its holding current through the fifth resistor R5, and the thyristor Q3 is maintained in the on state, and the PMOS tube Q2 is maintained in the off state until the first switch K1 is pressed to release the trigger state.
[0023] If there is a large electrolytic capacitor in the load circuit, at the moment of power-on, a large inrush current will flow through the first resistor R1, which may cause the overcurrent protection circuit to be triggered erroneously; the fourth resistor R4 and the second capacitor C2 are used to reduce the sensitivity of the overcurrent protection circuit and prevent the inrush current from triggering the overcurrent protection circuit.
[0024] In summary, the overcurrent protection circuit of the present utility model has a self-locking function. When the load current exceeds the set value, the overcurrent protection circuit will be triggered, the power output will be cut off, and the indicator light will be lit to prompt the user that the load current is overloaded. The overcurrent protection circuit maintains the triggered state until the user manually releases it. The overcurrent protection trigger indicator light facilitates the user to understand the working state of the overcurrent protection circuit, making the overcurrent protection circuit have better practicability.
[0025] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0026] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present utility model, and all of them should be covered within the protection scope of the present utility model.
[0027] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.
Claims
1. Overcurrent protection self-locking circuit, characterized in that: The emitter of the PNP transistor (Q1) and the first end of the first resistor (R1) are connected to a power supply VCC, the collector of the PNP transistor (Q1) is connected to the first end of the second resistor (R2) and the first end of the fourth resistor (R4), the second end of the second resistor (R2) is connected to GND, the base of the PNP transistor (Q1) is connected to the second end of the first resistor (R1), and is connected to the anode of the thyristor (Q3), the first end of the first capacitor (C1) and the source of the PMOS tube (Q2), and the fourth resistor (R4) The second end of the first resistor (R3) is connected to the first end of the second capacitor (C2), the first end of the first switch (K1) and the control electrode of the thyristor (Q3), the second end of the second capacitor (C2) is connected to GND, the second end of the first switch (K1) is connected to GND, the cathode of the thyristor (Q3) is connected to the anode of the diode (D1), the cathode of the diode (D1) is connected to the second end of the first capacitor (C1) and the first end of the third resistor (R3) and the gate of the PMOS tube (Q2), and the second end of the third resistor (R3) is connected to GND.
2. The overcurrent protection self-locking circuit according to claim 1, wherein: The cathode of the thyristor (Q3) is connected to the positive electrode of the indicator light (LED1), the negative electrode of the indicator light (LED1) is connected to the first end of the fifth resistor (R5), and the second end of the fifth resistor (R5) is connected to GND.
3. The overcurrent protection self-locking circuit according to claim 1, characterized in that: The drain of the PMOS tube (Q2) is connected to the load (L).
4. The overcurrent protection self-locking circuit according to claim 1, wherein: When the load current is less than the set value, the PNP transistor (Q1) is not turned on, the control electrode potential of the thyristor (Q3) is pulled down, the thyristor (Q3) is not turned on, the diode (D1) is reverse cutoff, the PMOS tube (Q2) is turned on, and the power supply VCC supplies power to the load; when the load current exceeds the set value, the PNP transistor (Q1) is saturated and turned on, the control electrode potential of the thyristor (Q3) is pulled up, and the thyristor (Q3) is turned on; at the same time, the gate potential of the PMOS tube (Q2) is pulled up, the PMOS tube (Q2) is turned off, and the power supply VCC stops supplying power to the load; due to The power source VCC stops supplying power to the load, no current flows through the first resistor (R1), the PNP transistor (Q1) is turned off, the control electrode potential of the thyristor (Q3) is pulled down, and due to the current limiting of the second resistor (R2) and the fourth resistor (R4), the turning off of the PNP transistor (Q1) cannot turn off the thyristor (Q3), and the current flowing through the thyristor (Q3) is set to be greater than its holding current through the fifth resistor (R5), so that the thyristor (Q3) is maintained in the on state and the PMOS tube (Q2) is maintained in the off state until the first switch (K1) is pressed to release the trigger state.
5. The overcurrent protection self-locking circuit according to claim 4, wherein: After the overcurrent protection is triggered, the thyristor (Q3) is turned on and the indicator light (LED1) is lit, indicating that the overcurrent protection circuit is currently in the triggered state.
6. The overcurrent protection self-locking circuit according to claim 4, wherein: The diode (D1) is used to control the current path of the first capacitor (C1) during the soft-start charging process of the PMOS tube (Q2).