A novel and simple overcurrent protection application circuit
By designing a simple overcurrent protection circuit and utilizing the characteristics of capacitor charging and transistors, the problems of slow response speed and high cost of existing circuits are solved, achieving fast and low-cost overcurrent protection, which is suitable for power management, motor drive and battery protection scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YAAN AVIONICS CO LTD
- Filing Date
- 2025-07-03
- Publication Date
- 2026-06-30
Smart Images
Figure CN224438541U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of overcurrent protection circuit technology, and more specifically, it relates to a novel simple overcurrent protection application circuit. Background Technology
[0002] Most existing overcurrent protection circuits on the market have limitations. Traditional fuses provide basic overcurrent protection, but once triggered, the fuse needs to be replaced, and their slow response time makes them unsuitable for timely protection against transient overcurrent surges. Electronic protection circuits, on the other hand, are often complex in design, resulting in higher costs and larger sizes, making them unsuitable for cost-sensitive and space-constrained electronic devices. Furthermore, some overcurrent protection solutions are not sensitive enough to small current overloads, failing to effectively protect the circuit. Therefore, there is an urgent need to develop a new, simplified overcurrent protection circuit. Utility Model Content
[0003] The purpose of this utility model is to provide a novel and simple overcurrent protection application circuit that can quickly detect overcurrent phenomena and react immediately, effectively protecting the circuit from damage caused by overcurrent; it is suitable for scenarios such as power management, motor drive, battery protection, and various electronic devices that require fast response, reliability, and cost-effectiveness in overcurrent protection.
[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution:
[0005] This application provides a novel, simple overcurrent protection application circuit, including:
[0006] The circuit is started, connected to the power supply, and provides power support for other circuits.
[0007] The self-locking circuit is connected to the starting circuit and is used to maintain the working state of the overcurrent protection application circuit after the starting circuit is connected to the power supply.
[0008] The undervoltage protection circuit is connected to the self-locking circuit and disconnects when the power supply connected to the starting circuit is lower than the voltage safety threshold.
[0009] The overcurrent protection circuit is connected to a self-locking circuit and disconnects when the load current exceeds the current safety threshold.
[0010] Based on the above technical solution, the present invention can be further improved as follows.
[0011] Furthermore, the aforementioned startup circuit includes resistors R9 and R8, capacitor C1, and transistor Q3, which are connected in a specific relationship.
[0012] Furthermore, the emitter and base of the transistor Q3 are respectively connected to the two ends of the resistor R9, and the emitter of the transistor Q3 forms the positive terminal of the power supply; one end of the resistor R8 is connected to the base of the transistor Q3, and the other end of the resistor R8 is connected to one end of the capacitor C1, and the other end of the capacitor C1 forms the negative terminal of the power supply.
[0013] Furthermore, the aforementioned self-locking circuit includes a transistor Q1, a resistor R1, and a diode D2 that are connected together.
[0014] Furthermore, the emitter and collector of the transistor Q1 are respectively connected to the two ends of the capacitor C1, and the emitter of the transistor Q1 is connected to the negative terminal formed by the capacitor C1.
[0015] The base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3.
[0016] Furthermore, the aforementioned undervoltage protection circuit includes transistor Q1, resistor R1, and diode D2, which are interconnected.
[0017] Furthermore, the emitter and collector of the transistor Q1 are respectively connected to the two ends of the capacitor C1, and the emitter of the transistor Q1 is connected to the negative terminal formed by the capacitor C1.
[0018] The base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3.
[0019] Furthermore, the aforementioned overcurrent protection circuit includes a resistor R3 and a transistor Q2.
[0020] Furthermore, the two ends of the aforementioned resistor R3 are respectively connected to the emitter and base of transistor Q2, and the emitter of transistor Q2 is connected to the negative terminal formed by capacitor C1. The base of transistor Q2 and the collector of transistor Q3 respectively form the load connection terminals for connecting the load.
[0021] Furthermore, the aforementioned voltage safety threshold is determined by the turn-on voltages of transistors Q1 and Q2; the current safety threshold is determined by calculating the voltage safety threshold and the resistance value of resistor R3.
[0022] Compared with the prior art, the present invention has at least the following beneficial effects:
[0023] The overcurrent protection circuit provided in this application uses relatively inexpensive components due to the focus on cost control in its circuit design, thus reducing the overall material cost. It also has a simple structure, which reduces the failure rate and the amount and cost of maintenance. At the same time, it can quickly cut off the current when an overcurrent is detected, thus protecting the circuit and equipment in a timely manner and reducing damage caused by overcurrent.
[0024] In this application, the provided overcurrent protection circuit achieves efficient overcurrent protection with a simple architecture. It can quickly detect overcurrent phenomena and react immediately, effectively protecting the circuit from damage caused by overcurrent. It is suitable for scenarios such as power management, motor drive, battery protection, and various electronic devices that require fast response, reliability, and cost-effectiveness in overcurrent protection. Attached Figure Description
[0025] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:
[0026] Figure 1 This is a schematic diagram of the circuit structure of the overcurrent protection application circuit in an embodiment of this utility model;
[0027] Figure 2 This is a schematic diagram of the connection of the overcurrent protection application circuit in an embodiment of this utility model. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0031] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0032] In the description of the embodiments of this utility model, "a plurality of" means at least two.
[0033] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0034] Example 1: Due to their complex design, electronic protection circuits are often costly and bulky, making them unsuitable for cost-sensitive and space-constrained electronic devices. Furthermore, some overcurrent protection schemes are not sensitive enough to small current overload conditions, failing to effectively protect the circuit. This example provides a novel, simplified overcurrent protection application circuit, such as... Figure 1 As shown, it includes:
[0035] The circuit is started, connected to the power supply, and provides power support for other circuits.
[0036] The aforementioned startup circuit includes resistors R9 and R8, capacitor C1, and transistor Q3, which are connected in a specific relationship. Figure 2 As shown, the specific connection relationships are as follows:
[0037] The emitter and base of transistor Q3 are connected to the two ends of resistor R9 respectively, and the emitter of transistor Q3 forms the positive terminal of the power supply. One end of resistor R8 is connected to the base of transistor Q3, and the other end of resistor R8 is connected to one end of capacitor C1, and the other end of capacitor C1 forms the negative terminal of the power supply.
[0038] Furthermore, the aforementioned overcurrent protection application circuit also includes a self-locking circuit, which is connected to the startup circuit and is used to maintain the working state of the overcurrent protection application circuit after the startup circuit is connected to the power supply.
[0039] The aforementioned self-locking circuit includes a transistor Q1, a resistor R1, and a diode D2 that are connected in a specific manner, such as... Figure 2 As shown, the specific connection relationships are as follows:
[0040] The emitter and collector of transistor Q1 are connected to the two ends of capacitor C1, and the emitter of transistor Q1 is connected to the negative terminal formed by capacitor C1. The base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3.
[0041] Furthermore, the aforementioned overcurrent protection application circuit also includes an undervoltage protection circuit, which is connected to a self-locking circuit and disconnects when the power supply connected to the startup circuit is lower than the voltage safety threshold.
[0042] In this embodiment, the undervoltage protection circuit and the self-locking circuit are the same circuit. That is, the circuit formed by transistor Q1, resistor R1 and diode D2 has the self-locking function and undervoltage protection function in the overall circuit. Therefore, the connection of transistor Q1, resistor R1 and diode D2 will not be described in detail here.
[0043] Furthermore, the aforementioned overcurrent protection application circuit also includes an overcurrent protection circuit connected to a self-locking circuit, which disconnects when the load current exceeds the current safety threshold.
[0044] The overcurrent protection circuit mentioned above includes resistor R3 and transistor Q2, such as Figure 2 As shown, the specific connection relationships are as follows:
[0045] The two ends of resistor R3 are connected to the emitter and base of transistor Q2, respectively. The emitter of transistor Q2 is connected to the negative terminal formed by capacitor C1. The base of transistor Q2 and the collector of transistor Q3 form the load terminals connected to the load.
[0046] Optionally, the voltage safety threshold is determined by the turn-on voltage of transistors Q1 and Q2; the current safety threshold is determined by the voltage safety threshold and the resistance value of resistor R3.
[0047] Specifically, the main function of an overcurrent protection circuit is to automatically cut off the power supply when the load current exceeds a safe threshold, thereby protecting the circuit from overcurrent damage; such as Figure 2 As shown, Figure 2The load R4 is used to simulate the connected load. When the load R4 decreases, resulting in excessive current, the current flowing through resistor R3 increases, and the voltage drop across resistor R3 also increases. When the voltage drop across resistor R3 reaches or exceeds the Vbe turn-on voltage of transistor Q2 (approximately 0.6V for the model used in this embodiment), transistor Q2 turns on. After transistor Q2 turns on, its collector-emitter voltage (Vce) drops to 0.1-0.3V (the specific value can be found in the transistor Q2 datasheet). The turn-on of transistor Q2 causes the base voltage of transistor Q1 to be clamped to 0.1-0.3V, which is lower than the Vbe turn-on voltage of transistor Q1 (approximately 0.6V), forcing transistor Q1 to turn off. After transistor Q1 turns off, the base current of transistor Q3 is cut off, causing transistor Q3 to also turn off, and the output voltage of the circuit is shut off, thereby achieving overcurrent protection.
[0048] Among them, according to Figure 2 The example schematic provides parameters, with the current limiting threshold (current safety threshold) = 0.6V / 5R = 0.12A. If the current exceeds 0.12A, the circuit will activate the overcurrent protection function and shut down the output voltage. It should be noted that the circuit parameters can be adjusted according to requirements to match the circuit to the corresponding drive capability, undervoltage protection threshold, and overcurrent protection threshold requirements.
[0049] Example 2: This example provides a novel and simple overcurrent protection application circuit, such as... Figure 1 As shown, it includes a startup circuit, a self-locking circuit, an undervoltage protection circuit, and an overcurrent protection circuit that are interconnected.
[0050] In the above, the starting circuit includes resistors R9 and R8, capacitor C1 and transistor Q3 that are connected; the self-locking circuit and the undervoltage protection circuit are the same circuit, that is, the same circuit realizes the self-locking function and the undervoltage protection function at the same time, which includes transistor Q1, resistor R1 and diode D2 that are connected; the overcurrent protection circuit includes resistor R3 and transistor Q2 that are connected.
[0051] Specifically, such as Figure 2As shown, the emitter and base of transistor Q3 are connected to the two ends of resistor R9, and the emitter of transistor Q3 forms the positive terminal for connecting to the power supply; one end of resistor R8 is connected to the base of transistor Q3, and the other end of resistor R8 is connected to one end of capacitor C1, which forms the negative terminal for connecting to the power supply; the emitter and collector of transistor Q1 are connected to the two ends of capacitor C1, and the emitter of transistor Q1 is connected to the negative terminal formed by capacitor C1; the base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3; the two ends of resistor R3 are connected to the emitter and base of transistor Q2, and the emitter of transistor Q2 is connected to the negative terminal formed by capacitor C1; the base of transistor Q2 and the collector of transistor Q3 form the load terminals for connecting to the load.
[0052] The working principle of each circuit is further explained below:
[0053] The startup circuit consists of resistors R9 and R8, capacitor C1, and transistor Q3. At the instant the circuit is powered on, capacitor C1 begins to charge through resistors R9 and R8; at this time, the voltage across capacitor C1 gradually increases from 0V. Due to the physical characteristics of a capacitor, in the initial stage of charging, the equivalent resistance of the capacitor is close to 0Ω, exhibiting a state similar to a short circuit.
[0054] Due to the low impedance of capacitor C1 during the initial charging phase, the base voltage of transistor Q3 rapidly drops to near 0V, causing Q3 to quickly turn on. This process, a result of the capacitor's rapid charging, ensures that transistor Q3 can respond promptly to the circuit's power-on operation. As transistor Q3 turns on, the voltage difference between its collector and emitter decreases, generating a collector output voltage that provides the necessary power support for the normal operation of subsequent circuits.
[0055] The self-locking circuit is a key component that ensures that the circuit can automatically maintain its working state after power-on. In this embodiment, the self-locking circuit consists of transistor Q1, resistor R1, and diode D2. When the circuit is powered on, the collector output voltage of transistor Q3 is applied to the base of transistor Q1 through resistor R1 and diode D2, which triggers transistor Q1 to conduct. Once transistor Q1 is turned on, the voltage drop between its collector and emitter will decrease, thereby further reducing the voltage at the base of transistor Q1. This change keeps transistor Q1 in the conducting state, even if the initial trigger signal is removed. This self-maintained working state is the self-locking mechanism.
[0056] Because transistor Q1 is continuously turned on, the collector of transistor Q3 can continuously output a stable voltage. This stable voltage output is the key to the normal operation of the circuit, ensuring the reliability and stability of the circuit.
[0057] In this embodiment, the undervoltage protection circuit and the self-locking circuit are the same circuit, both consisting of resistor R1, diode D2 and transistor Q1. The purpose is to ensure that the circuit automatically disconnects when the input voltage is lower than a certain safety threshold, thereby protecting the circuit from the effects of low voltage.
[0058] When the input voltage drops below the Zener diode D2's regulated voltage (18V in this embodiment) plus the base-emitter voltage (Vbe, approximately 0.6V) of transistor Q1, the base voltage of transistor Q1 is insufficient to turn it on, and transistor Q1 is turned off. After transistor Q1 is turned off, the base current of transistor Q3 is cut off, causing transistor Q3 to also be turned off. Since transistor Q3 is turned off, the circuit's output voltage is shut off, thus achieving undervoltage protection.
[0059] The overcurrent protection circuit consists of resistor R3, transistor Q2, and load resistor R4. Its main function is to automatically cut off the power supply when the load current exceeds the safety threshold, so as to protect the circuit from overcurrent damage.
[0060] like Figure 2 As shown, Figure 2 The load R4 is used to simulate the connected load. When the load R4 decreases, resulting in excessive current, the current flowing through resistor R3 increases, and the voltage drop across resistor R3 also increases. When the voltage drop across resistor R3 reaches or exceeds the Vbe turn-on voltage of transistor Q2 (approximately 0.6V for the model used in this embodiment), transistor Q2 turns on. After transistor Q2 turns on, its collector-emitter voltage (Vce) drops to 0.1-0.3V (the specific value can be found in the transistor Q2 datasheet). The turn-on of transistor Q2 causes the base voltage of transistor Q1 to be clamped to 0.1-0.3V, which is lower than the Vbe turn-on voltage of transistor Q1 (approximately 0.6V), forcing transistor Q1 to turn off. After transistor Q1 turns off, the base current of transistor Q3 is cut off, causing transistor Q3 to also turn off, and the output voltage of the circuit is shut off, thereby achieving overcurrent protection.
[0061] Among them, according to Figure 2 The example schematic provides parameters, with the current limiting threshold (current safety threshold) = 0.6V / 5R = 0.12A. If the current exceeds 0.12A, the circuit will activate the overcurrent protection function and shut down the output voltage. It should be noted that the circuit parameters can be adjusted according to requirements to match the circuit to the corresponding drive capability, undervoltage protection threshold, and overcurrent protection threshold requirements.
[0062] This embodiment provides a circuit design integrating startup, self-locking, undervoltage, and overcurrent protection functions. Through careful selection of components and parameter configuration, comprehensive circuit protection is achieved. This design utilizes physical characteristics such as capacitor charging and transistor conduction to ensure the circuit automatically maintains or disconnects its operating state under power-on, undervoltage, and overcurrent conditions, while allowing adjustment of the protection threshold according to actual needs. This circuit design is simple, low-cost, and suitable for various application scenarios requiring fast response and hardware protection, providing a reliable and efficient protection solution for power electronic equipment. This overcurrent protection application circuit has at least the following advantages:
[0063] 1. This circuit is comprehensive and its parameters can be adjusted according to the actual driving power to reproduce the circuit function and be directly applied;
[0064] 2. This circuit has undervoltage and overcurrent output protection capabilities, which are implemented directly in hardware without any additional overhead;
[0065] 3. The protection current can be adjusted by changing the value of the sampling resistor to achieve different overload protection requirements;
[0066] 4. Implemented in hardware, enabling rapid startup and protection;
[0067] 5. This solution has a simple circuit and is practical for applications with low cost requirements.
[0068] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.
Claims
1. A novel, simple overcurrent protection application circuit, characterized in that, include: The circuit is started, connected to the power supply, and provides power support for other circuits. A self-locking circuit, which is connected to the starting circuit, is used to maintain the working state of the overcurrent protection application circuit after the starting circuit is connected to the power supply. An undervoltage protection circuit is provided, which is connected to the self-locking circuit and disconnects when the power supply connected to the starting circuit is lower than the voltage safety threshold. An overcurrent protection circuit is provided, which is connected to the self-locking circuit and disconnects when the load current exceeds the current safety threshold.
2. The novel simplified overcurrent protection application circuit according to claim 1, characterized in that, The startup circuit includes resistors R9 and R8, capacitor C1, and transistor Q3, which are connected together.
3. The novel simplified overcurrent protection application circuit according to claim 2, characterized in that, The emitter and base of transistor Q3 are respectively connected to the two ends of resistor R9, and the emitter of transistor Q3 forms the positive terminal of the power supply; one end of resistor R8 is connected to the base of transistor Q3, and the other end of resistor R8 is connected to one end of capacitor C1, and the other end of capacitor C1 forms the negative terminal of the power supply.
4. A novel simplified overcurrent protection application circuit according to claim 2, characterized in that, The self-locking circuit includes a transistor Q1, a resistor R1, and a diode D2 that are connected together.
5. A novel simplified overcurrent protection application circuit according to claim 4, characterized in that, The emitter and collector of transistor Q1 are respectively connected to the two ends of capacitor C1, and the emitter of transistor Q1 is connected to the negative terminal formed by capacitor C1. The base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3.
6. A novel simplified overcurrent protection application circuit according to claim 2, characterized in that, The undervoltage protection circuit includes transistor Q1, resistor R1, and diode D2, which are in a circuit relationship.
7. A novel simplified overcurrent protection application circuit according to claim 6, characterized in that, The emitter and collector of transistor Q1 are respectively connected to the two ends of capacitor C1, and the emitter of transistor Q1 is connected to the negative terminal formed by capacitor C1. The base of transistor Q1 is connected to the input terminal of diode D2, the output terminal of diode D2 is connected to one end of resistor R1, and the other end of resistor R1 is connected to the base of transistor Q3.
8. A novel simplified overcurrent protection application circuit according to claim 4 or 6, characterized in that, The overcurrent protection circuit includes a resistor R3 and a transistor Q2.
9. A novel simplified overcurrent protection application circuit according to claim 8, characterized in that, The two ends of the resistor R3 are respectively connected to the emitter and base of the transistor Q2, and the emitter of the transistor Q2 is connected to the negative terminal formed by the capacitor C1. The base of the transistor Q2 and the collector of the transistor Q3 respectively form the load connection terminals for connecting the load.
10. A novel simplified overcurrent protection application circuit according to claim 8, characterized in that, The voltage safety threshold is determined by the on-state voltages of transistors Q1 and Q2; the current safety threshold is calculated by the voltage safety threshold and the resistance value of resistor R3.