Overcurrent protection device

Abstract

The invention discloses an over-current protection device, relates to the technical field of electronic circuits, and is used for solving the problem that the availability of equipment is reduced since a system is completely closed after an over-current protection circuit is triggered and power supply can be recovered only by manual intervention or overall restart of the system in the prior art. The device comprises a power switch connected in series between a power supply and a load; the current detection module is used for detecting target current flowing from the power supply to the load; the first overcurrent protection module is connected with the current detection module and the power switch and used for triggering self-locking and turning off the power switch under the condition that the target current is larger than or equal to a first threshold value, and the self-locking can be relieved in response to the reset signal.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to an overcurrent protection device. Background Technology

[0002] In modern electronic devices, overcurrent protection has become a fundamental requirement to prevent damage to power supplies or critical circuits caused by excessive current due to abnormal loads (such as short circuits or component failures). In related technologies, overcurrent protection circuits typically employ a single threshold comparison scheme. When the load current exceeds a preset threshold, the overcurrent protection circuit is triggered and cuts off the power switch, thus disconnecting the load. While this protection mechanism is simple and reliable, for brief transient overcurrents or minor overloads, the system will be completely shut down after the overcurrent protection circuit is triggered. Manual intervention or a complete system restart is required to restore power, reducing equipment availability. Summary of the Invention

[0003] Based on this, an overcurrent protection device, method, computer equipment, and storage medium are provided to solve the problem in related technologies where the system is completely shut down after the overcurrent protection circuit is triggered, requiring manual intervention or a complete system restart to restore power supply, resulting in reduced equipment availability.

[0004] This invention provides an overcurrent protection device, the device comprising: A power switch is connected in series between the power source and the load. A current detection module is used to detect the target current flowing from the power source to the load; A first overcurrent protection module, connected to the current detection module and the power switch, is used to trigger a self-locking mechanism to turn off the power switch when the target current is greater than or equal to a first threshold, wherein the self-locking mechanism can be released in response to a reset signal.

[0005] In one embodiment, the device further includes a second overcurrent protection module connected to the current detection module and the power switch; The first overcurrent protection module is used to trigger the self-locking to turn off the power switch when the target current is greater than or equal to a first threshold and less than a second threshold. The second overcurrent protection module is used to directly turn off the power switch when the target current is greater than or equal to the second threshold.

[0006] In one embodiment, the current detection module includes at least one sampling resistor connected in series between the power supply and the power switch to generate a voltage drop signal proportional to the target current. The current detection module obtains the target current by detecting the voltage drop signal.

[0007] In one embodiment, the first overcurrent protection module includes at least: A detection unit, connected to the current detection module, is used to output a trigger signal when the target current is greater than or equal to the first threshold. A protection unit, connected to the detection unit and the power switch, is configured to trigger a self-locking mechanism in response to the trigger signal, output a first control signal to turn off the power switch, and release the self-locking mechanism in response to the reset signal.

[0008] In one embodiment, the detection unit includes at least a first voltage divider resistor and a first trigger transistor; The first end of the first voltage divider resistor is connected between the sampling resistor of the current detection module and the power switch; the second end of the first voltage divider resistor is connected to the control electrode of the first trigger transistor; the first main electrode of the first trigger transistor is connected to the reference potential. The first voltage divider resistor and the sampling resistor in the current detection module are connected in series to form a first voltage divider circuit, which is used to turn on the first trigger transistor when the target current is greater than or equal to the first threshold, and output the trigger signal through the second main electrode of the first trigger transistor.

[0009] In one embodiment, the protection unit includes at least a first switching device, a second switching device, and a reset switching device; the first conducting terminals of the first switching device, the second switching device, and the reset switching device are connected to a reference potential. The control terminal of the first switching device is connected to the detection unit and is used to turn on in response to the trigger signal; The second conducting terminal of the first switching device is connected to the control terminal of the second switching device, and the second conducting terminal of the second switching device is connected to the control terminal of the first switching device, so that the first switching device and the second switching device form a positive feedback self-locking loop. The control terminal of the reset switch device is used to receive the reset signal, and the second conducting terminal of the reset switch device is connected to the control terminal of the second switch device, and is used to conduct in response to the reset signal to release the positive feedback self-locking loop; The protection unit outputs the first control signal through the second conducting terminal of the second switching device.

[0010] In one embodiment, the first switching device, the second switching device, and the reset switching device are all bipolar junction transistors; The control terminal corresponds to the base, the first conducting terminal corresponds to the emitter, and the second conducting terminal corresponds to the collector.

[0011] In one embodiment, the device further includes a reset signal source connected to the first overcurrent protection module, wherein the reset signal source is a self-excited oscillation circuit used to generate the periodic reset signal.

[0012] In one embodiment, the second overcurrent protection module includes at least: a second voltage divider resistor and a second trigger transistor; the resistance value of the second voltage divider resistor is less than the resistance value of the first voltage divider resistor; The first end of the second voltage divider resistor is connected between the sampling resistor of the current detection module and the power switch, and the second end of the second voltage divider resistor is connected to the control electrode of the second trigger transistor. The first main electrode of the second trigger transistor is connected to the reference potential, and the second main electrode of the second trigger transistor is connected to the power switch; The second voltage divider resistor and the sampling resistor in the current detection module are connected in series to form a second voltage divider circuit, which is used to turn on the second trigger transistor when the target current is greater than or equal to the second threshold, and output a second control signal through the second main electrode of the second trigger transistor to turn off the power switch.

[0013] In one embodiment, the power switch is a field-effect transistor; The first main electrode of the power switch is connected to the current detection module, the second main electrode of the power switch is connected to the load, and the control electrode of the power switch is connected to the first overcurrent protection module and the second overcurrent protection module. The first control signal and the second control signal are used to adjust the control electrode voltage of the power switch to a preset shutdown threshold to turn off the power switch.

[0014] In one embodiment, the device further includes an isolation module connected between the output terminals of the first overcurrent protection module and the second overcurrent protection module and the control electrode of the power switch; The isolation module is used to receive a first control signal output by the first overcurrent protection module and / or a second control signal output by the second overcurrent protection module, and convert the first control signal and / or the second control signal into a drive signal to drive the power switch to turn off.

[0015] In one embodiment, the isolation module includes at least a third switching device and a driving switching device; The control terminal of the third switching device is connected to the output terminals of the first overcurrent protection module and the second overcurrent protection module, and is used to turn on in response to the first control signal or the second control signal; the first conducting terminal of the third switching device is connected to the first reference potential. The second conducting terminal of the third switching device is connected to the control terminal of the driving switching device; the first conducting terminal of the driving switching device is connected to the second reference potential, and the second conducting terminal of the driving switching device is connected to the control electrode of the power switch. Wherein, the first reference potential and the second reference potential are two different DC potential nodes; The driving switch device is configured to turn on in response to the turn-on of the third switch device, and output the voltage of the second reference potential as the driving signal to the control electrode of the power switch to turn off the power switch.

[0016] In one embodiment, the device further includes an overvoltage protection module connected between the first main electrode and the control electrode of the power switch; The overvoltage protection module is used to clamp the voltage between the control electrode of the power switch and the first main electrode within a preset safety value.

[0017] The aforementioned overcurrent protection device provides intelligent, automatically recoverable protection based on the first overcurrent protection module during minor overcurrent events, preventing accidental shutdown due to momentary overload and improving equipment availability. During severe overcurrent events, it implements rapid, irreversible hard shutdown protection based on the second overcurrent protection module, ensuring absolute system safety. The entire protection process is automatically completed by the hardware circuitry without software intervention, improving equipment intelligence and reliability while reducing implementation costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an application scenario applicable to an embodiment of this application; Figure 2 This is a structural block diagram of the overcurrent protection device 11 in one embodiment; Figure 3 This is a schematic diagram of the circuit structure of the power supply module 24 in one embodiment; Figure 4 This is a schematic diagram of the circuit structure of the power switch 20 in one embodiment; Figure 5 This is a schematic diagram of the circuit structure of the current detection module 21 in one embodiment; Figure 6 This is a schematic diagram of the circuit structure of the first overcurrent protection module 22 in one embodiment; Figure 7This is a schematic diagram of the circuit structure of the reset signal source 25 in one embodiment; Figure 8 This is a schematic diagram of the circuit structure of the second overcurrent protection module 23 in one embodiment; Figure 9 This is a schematic diagram of the circuit structure of the isolation module 26 in one embodiment; Figure 10 This is a schematic diagram of the circuit structure of the overvoltage protection module 27 in one embodiment; Figure 11 This is a schematic diagram of the circuit structure of the overcurrent protection device 11 in one embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this invention, "multiple" is understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing together, or B existing alone. A connected to B can represent: A and B directly connected, or A and B connected through C. Furthermore, in the description of this invention, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or order.

[0020] Before introducing the overcurrent protection device provided by this invention, the technical background of this invention will be described in detail below for ease of understanding.

[0021] In modern electronic devices, overcurrent protection has become a fundamental requirement to prevent damage to power supplies or critical circuits caused by excessive current due to abnormal loads (such as short circuits or component failures). In related technologies, overcurrent protection circuits typically employ a single threshold comparison scheme. This means that when the detected load current exceeds a preset threshold, the overcurrent protection circuit is triggered and the power switch is cut off, thereby disconnecting the load. While this protection mechanism is simple and reliable, it has significant drawbacks in practical applications: In complex application scenarios (such as motor starting and capacitive load power-on), brief and small-amplitude current surges often occur. These surges are within the normal operating range and should not trigger protection. However, if the protection threshold is set too high to tolerate such surges, the overcurrent protection circuit cannot be triggered in time when a true, low-amplitude overload fault occurs, posing a safety hazard. Furthermore, for brief transient overcurrents or minor overloads, the system will be completely shut down after the overcurrent protection circuit is triggered, requiring manual intervention or a system restart to restore power, thus reducing equipment availability.

[0022] In addition, a chip-based overcurrent protection scheme has been proposed in related technologies. These chips integrate intelligent control logic, enabling advanced functions such as automatic recovery after fault clearance. However, their implementation typically requires software programming, which increases the complexity of system design and software development costs. Furthermore, the program flow itself has inherent digital latency, making it less than ideal for cost-sensitive applications or those requiring extremely high real-time performance (such as certain industrial control and automotive electronics fields).

[0023] In view of this, the present invention provides an overcurrent protection device, method, computer device, and storage medium to solve the problems of overcurrent protection in the related art in terms of cost, design complexity, real-time performance, and pure hardware self-recovery capability without software intervention.

[0024] The following is a brief introduction to the application scenarios to which the technical solution of the present invention is applicable. It should be noted that the application scenarios described below are for illustrative purposes only and are not intended to limit the scope of the invention. In specific implementations, the technical solution provided by the present invention can be flexibly applied according to actual needs.

[0025] Figure 1 This is a schematic diagram illustrating an application scenario applicable to the embodiments of this application. For example... Figure 1 As shown, it mainly includes a power supply 10, an overcurrent protection device 11, and a load 12. The overcurrent protection device 11 is connected in series between the power supply 10 and the load 12.

[0026] Power source 10 is used to provide operating electrical energy. Power source 10 can be a battery, and its output terminal provides the battery voltage as the operating voltage. Under normal operating conditions, this operating voltage is applied to the load 12 via overcurrent protection device 11, thereby forming the main power supply circuit from power source 10 to overcurrent protection device 11 and then to load 12. It can be understood that... Figure 1 The example shown only shows a load of 12; in real-world applications, the number of loads can be one or more.

[0027] The overcurrent protection device 11 is used to provide overcurrent protection for the load 12. Specifically, the overcurrent protection device 11 is configured to implement graded protection based on the severity of the overcurrent. For example, when a minor overcurrent is detected, a protection action that can automatically attempt recovery is performed; when a severe overcurrent is detected, a lockout protection action is performed. The entire protection process of the overcurrent protection device 11 can be implemented through pure hardware circuitry without the need for software intervention.

[0028] Figure 2 This is a structural block diagram of an overcurrent protection device 11 in one embodiment. Figure 2 As shown, the overcurrent protection device 11 includes: A power switch 20 is connected in series between the power supply 10 and the load 12 to switch the connection between the power supply 10 and the load 12. The current detection module 21 is connected between the power supply 10 and the power switch 20 and is used to detect the target current flowing from the power supply 10 to the load 12. The first overcurrent protection module 22 is connected to the current detection module 21 and the power switch 20. It is used to trigger a self-locking mechanism and turn off the power switch 20 when the target current is greater than or equal to a first threshold. The self-locking mechanism can be released in response to a reset signal.

[0029] For example, the connection relationship of each functional module is as follows: the input terminal of the current detection module 21 is connected to the power supply 10 for receiving the voltage of the power supply 10; the output terminal of the current detection module 21 is connected to both the power switch 20 and the input terminal of the first overcurrent protection module 22. The output terminal of the power switch 20 is connected to the load 12. The output terminal of the first overcurrent protection module 22 is connected to the power switch 20 for outputting a control signal to control its on / off state.

[0030] Based on the above connection relationship, the current detection module 21 samples the target current flowing through it in real time and sends it to the first overcurrent protection module 22. When the target current exceeds the first threshold, the first overcurrent protection module 22 is triggered, enters a self-locking state, and sends a first control signal to the power switch 20 through its output terminal to turn it off. This self-locking state can be released after receiving a reset signal.

[0031] Based on the above device, intelligent protection that can automatically recover is realized based on the first overcurrent protection module 22 during overcurrent, avoiding false shutdown caused by instantaneous overload and improving equipment availability.

[0032] In one embodiment, exemplarily illustrated, such as Figure 2 As shown, the overcurrent protection device 11 also includes a second overcurrent protection module 23, which is connected to the current detection module 21 and the power switch 20.

[0033] The first overcurrent protection module 22 is used to trigger a self-locking mechanism to turn off the power switch 20 when the target current is greater than or equal to the first threshold and less than the second threshold. The second overcurrent protection module 23 is used to directly turn off the power switch 20 when the target current is greater than or equal to the second threshold. At this time, the second overcurrent protection module 23 does not respond to the reset signal.

[0034] For example, the connection relationship of each functional module is as follows: the input terminal of the current detection module 21 is connected to the power supply 10 to receive the voltage of the power supply 10; the output terminal of the current detection module 21 is simultaneously connected to the input terminals of the power switch 20, the first overcurrent protection module 22, and the second overcurrent protection module 23. The output terminal of the power switch 20 is connected to the load 12, thus forming a complete main power supply circuit.

[0035] The output terminals of the first overcurrent protection module 22 and the second overcurrent protection module 23 are connected to the power switch 20 to output control signals to control its on / off state.

[0036] Based on the above connection, the current detection module 21 samples the target current flowing through the main power supply circuit in real time and sends it to the two overcurrent protection modules. When the target current exceeds the first threshold, the first overcurrent protection module 22 is triggered, enters a self-locking state, and sends a first control signal to the power switch 20 through its output terminal to turn it off. This self-locking state can be released after receiving a reset signal. When the target current reaches a second threshold that is larger than the first threshold, the second overcurrent protection module 23 is directly triggered, and sends a second control signal to the power switch 20 through its output terminal to force it to turn off. This shutdown action is independent of the reset signal, that is, the second overcurrent protection module 23 does not respond to the reset signal.

[0037] Based on the above device, in the event of a minor overcurrent, the first overcurrent protection module provides intelligent protection that can automatically recover, avoiding accidental shutdown due to instantaneous overload and improving equipment availability; in the event of a severe overcurrent, the second overcurrent protection module implements rapid and irreversible hard shutdown protection to ensure absolute system safety.

[0038] In one embodiment, exemplarily illustrated, such as Figure 2 As shown, the overcurrent protection device 11 also includes a power supply module 24, which is connected between the power supply 10 and the current detection module 21, and is used to provide a stable operating voltage for the internal circuit of the overcurrent protection device 11.

[0039] The power supply module 24 may include a first current-limiting resistor and a first Zener diode. The first end of the first current-limiting resistor is connected to the power supply 10, and the second end of the first current-limiting resistor is connected to the cathode of the first Zener diode, with the anode of the first Zener diode grounded. Through the cooperation of the first current-limiting resistor and the first Zener diode, a stable supply voltage is generated at the cathode of the first Zener diode.

[0040] To optimize the power quality of the power supply 10 and reduce noise interference, the power supply module 24 may also include a filter circuit, wherein the filter circuit includes at least one filter capacitor connected in parallel across the first Zener diode.

[0041] like Figure 3The diagram shows a circuit structure of the power supply module 24 in one embodiment. In this circuit, the power supply 10 provides the power supply voltage (labeled VBAT). The power supply module 24 includes a first current-limiting resistor R797, a first Zener diode D75, and a filter circuit consisting of a first capacitor C450 and a second capacitor C451 connected in parallel. The first terminal of R797 is connected to VBAT, and the second terminal of R797 is connected to the cathode of D75. The connection point between the second terminal of R797 and the cathode of D75 serves as the voltage output terminal of the power supply module 24. The anode of D75 is connected to ground (GND). C450 and C451 are connected in parallel across D75 (i.e., in parallel between the voltage output terminal and GND) to perform graded filtering of the stable output voltage. The voltage output terminal of the power supply module 24 is connected to the input terminal of the current detection module 21.

[0042] The capacitance values ​​of C450 and C451 differ. For example, C450 can be a large electrolytic capacitor (e.g., 10 microfarads (μF)) primarily used to filter low-frequency noise; C451 can be a small ceramic capacitor (e.g., 0.1 μF) primarily used to filter high-frequency noise. By combining capacitors of different capacitance values ​​in parallel, a wide-bandwidth hierarchical filtering of the stable power supply voltage can be achieved, effectively suppressing noise from different frequency bands from power supply 10, thereby improving the stability and anti-interference capability of the subsequent overcurrent protection device 11.

[0043] In one embodiment, the power switch 20 is exemplarily described as a field-effect transistor.

[0044] The first main electrode of the power switch 20 is connected to the current detection module 21, the second main electrode of the power switch 20 is connected to the load 12, and the control electrode of the power switch 20 is connected to the first overcurrent protection module 22 and the second overcurrent protection module 23. The first control signal and the second control signal are used to adjust the voltage of the control electrode of the power switch 20 to a preset shutdown threshold to turn off the power switch 20.

[0045] For example, the field-effect transistor can be a metal-oxide-semiconductor field-effect transistor (MOSFET), such as an N-channel MOSFET (NMOS) or a P-channel MOSFET (PMOS). The specific field-effect transistor depends on the situation and is not limited here.

[0046] When the power switch 20 is a PMOS, its first main electrode corresponds to the source, its second main electrode corresponds to the drain, and its control electrode is the gate. It is turned off by adjusting the voltage of its control electrode to be close to or equal to the voltage of its first main electrode.

[0047] When the power switch 20 is an NMOS, its first main electrode corresponds to the drain, its second main electrode corresponds to the source, and its control electrode is the gate. Turn-off is achieved by adjusting the voltage of its control electrode to be close to or equal to the voltage of its second main electrode.

[0048] like Figure 4 The diagram shown is a schematic of the circuit structure of the power switch 20 in one embodiment. In this circuit, a PMOS is used as the power switch 20 (labeled Q62). The gate (labeled G) of Q62 is connected to the output terminals of the first overcurrent protection module 22 and the second overcurrent protection module 23; the source (labeled S) of Q62 is connected to the output terminal of the current detection module 21 to receive the current from the power supply 10 after detection; the drain (labeled D) of Q62 is connected to the load 12.

[0049] When any overcurrent protection module is triggered, its output control signal will act on G, raising the voltage of G to near the voltage of S. This action directly satisfies the turn-off condition of Q62, thereby efficiently and reliably cutting off the main power supply circuit from power supply 10 to load 12, realizing the overcurrent protection function.

[0050] Based on the above device, a field-effect transistor is used as the power switch 20, and its gate is controlled by the control signals of two overcurrent protection modules. When any one of the overcurrent protection modules is triggered, the corresponding control signal can quickly adjust the control electrode voltage of the power switch 20 to the preset shutdown threshold, thereby forcibly shutting down the power switch 20 and ensuring the speed and accuracy of the response.

[0051] In one embodiment, for example, the current detection module 21 includes at least one sampling resistor connected in series in the main power supply circuit. When the target current flows through the sampling resistor, a voltage drop signal proportional to the target current is generated across its terminals. By detecting the magnitude of the voltage drop signal, the target current can be monitored.

[0052] like Figure 5 The diagram shown illustrates the circuit structure of the current detection module 21 in one embodiment. In this circuit, the current detection module 21 is composed of a sampling resistor circuit, which includes three parallel sampling resistors: a first sampling resistor R667, a second sampling resistor R670, and a third sampling resistor R704. This parallel structure can improve the reliability of the detection circuit by sharing the current while ensuring the required sampling resistance value.

[0053] Based on the above device, the main circuit current is linearly converted into a voltage signal by utilizing the resistance characteristics of the sampling resistor, realizing direct, real-time and low-cost accurate detection of the load current, and providing an accurate and reliable judgment basis for subsequent graded overcurrent protection logic.

[0054] In one embodiment, the first overcurrent protection module 22 is illustrated by way of example, including but not limited to: The detection unit, connected to the current detection module 21, is used to output a trigger signal when the target current is greater than or equal to a first threshold and less than a second threshold. The protection unit, connected to the detection unit and the power switch 20, is used to trigger self-locking in response to a trigger signal, output a first control signal to turn off the power switch 20, and release self-locking in response to a reset signal.

[0055] Based on the above device, when a slight overcurrent is detected, the self-locking mechanism can be triggered immediately to shut off the power switch 20, effectively isolating the fault. At the same time, the self-locking state can be intelligently released by a reset signal, so that when the fault disappears, the system can automatically attempt to restore power supply. Thus, under the premise of ensuring safety, the availability and continuity of the equipment in dealing with instantaneous or slight overloads are significantly improved.

[0056] In one embodiment, the detection unit is illustrated by way of example, including but not limited to: a first voltage divider resistor and a first trigger transistor (the active amplification and threshold comparison function of the transistor is emphasized here).

[0057] The first end of the first voltage divider resistor is connected between the current detection module 21 and the power switch 20 (i.e., the output terminal of the current detection module 21, which is at a low potential), and the second end of the first voltage divider resistor is connected to the control electrode of the first trigger transistor. The first main electrode of the first trigger transistor is connected to a reference potential, such as GND or the input terminal of the current detection module 21, which is equivalent to VBAT, and is at a high potential. The specific reference potential is determined according to the device type of the first trigger transistor.

[0058] The first voltage divider resistor and the sampling resistor in the current detection module 21 are connected in series to form a first voltage divider circuit (the first threshold can be set by setting the resistance value of the first voltage divider resistor), which is used to turn on the first trigger transistor when the target current exceeds the first threshold and output a trigger signal through the second main electrode of the first trigger transistor.

[0059] The first trigger transistor can be an NPN transistor (with the control electrode as the base, the first main electrode as the emitter, the second main electrode as the collector, and the reference potential as GND), a PNP transistor (with the control electrode as the base, the first main electrode as the emitter, the second main electrode as the collector, and the reference potential as VBAT), an NMOS (corresponding to the NPN transistor, with G corresponding to the base, S corresponding to the emitter, D corresponding to the collector, and the reference potential as GND), or a PMOS (corresponding to the PNP transistor, with G corresponding to the base, S corresponding to the emitter, D corresponding to the collector, and the reference potential as VBAT), etc.

[0060] Based on the above device, the target current is accurately converted into a voltage signal through the first voltage divider circuit, and the nonlinear amplification characteristics of the first trigger transistor are used to achieve accurate and rapid detection of the first threshold and generate a reliable trigger signal, providing accurate start-up conditions for the subsequent self-locking protection circuit.

[0061] In one embodiment, exemplarily illustrated, the protection unit includes, but is not limited to, a first switching device, a second switching device, and a reset switching device (the emphasis here is on the switching logic function of the switching devices). The first conducting terminals of the first switching device, the second switching device, and the reset switching device are connected to a reference potential.

[0062] The control terminal of the first switching device is connected to the detection unit and is used to turn on in response to a trigger signal; The second conducting terminal of the first switching device is connected to the control terminal of the second switching device, and the second conducting terminal of the second switching device is connected to the control terminal of the first switching device, so that the first switching device and the second switching device form a positive feedback self-locking loop. The control terminal of the reset switch device is used to receive a reset signal. The second conducting terminal of the reset switch device is connected to the control terminal of the second switch device and is used to conduct in response to the reset signal to release the positive feedback self-locking loop.

[0063] The protection unit outputs a first control signal through the second conducting terminal of the second switching device.

[0064] Based on the above device, a pure hardware positive feedback self-locking loop is constructed by the first and second switching devices, realizing reliable latching protection for the first-stage overcurrent state. At the same time, by connecting the second conducting terminal of the reset switching device to the key node of the loop, a hardware reset mechanism that can be forcibly triggered by an external signal is realized, thereby providing the system with automatic and reliable fault recovery capability while ensuring the stability of the overcurrent protection action.

[0065] In one embodiment, exemplarily, the first switching device, the second switching device, and the reset switching device are all bipolar junction transistors, such as NPN transistors (reference potential GND). The NPN transistor is configured to turn on when the base potential is higher than the emitter potential, and the difference is greater than or equal to the NPN transistor's turn-on threshold. Alternatively, a PNP transistor (reference potential VBAT) is configured to turn on when the emitter potential is higher than the base potential, and the difference is greater than or equal to the PNP transistor's turn-on threshold.

[0066] Alternatively, the switching device can also be NMOS, PMOS, etc., which correspond to NPN transistors and NPN transistors respectively. As mentioned above, they will not be described again here. The specific device depends on the situation and is not limited here.

[0067] In addition, the polarity types of the first trigger transistor, the first switching device, the second switching device, the reset switching device, and the power switch 20 are adapted and set according to the potential relationship of their respective circuits and the logic state to be controlled, so that the first overcurrent protection module 22 can realize a complete functional chain of detection, self-locking, reset, and shutdown.

[0068] Based on the above device, a specific circuit implementation method is provided to realize stable and reliable self-locking and reset functions by utilizing the advantages of bipolar junction transistors (BJTs) in terms of clear current drive characteristics, stable on-state voltage drop, and low cost. This ensures the controllable latching and accurate release of the overcurrent protection state at the pure hardware level.

[0069] Figure 6 The diagram below shows the circuit structure of the first overcurrent protection module 22 in one embodiment. In this circuit, a PMOS is used as the power switch 20 (marked as Q62), the first trigger transistor (marked as Q65), the second switching device (marked as Q64) and the reset switching device (marked as Q63) are all PNP type transistors, and an NPN type transistor is used as the first switching device (marked as Q68).

[0070] The detection unit consists of a first voltage divider resistor R707 and Q65. The first terminal of R707 is connected to the output of the sampling resistor circuit (R667, R670, R704), and the second terminal of R707 is connected to the base of Q65. The emitter of Q65 is connected to VBAT, and its collector serves as the output of the detection unit.

[0071] For example, the voltage drop signal generated on the sampling resistor circuit, which is proportional to the target current, will act on the first voltage divider circuit formed by the sampling resistor circuit and R707. When the target current is less than the first threshold, the voltage drop of the sampling resistor circuit is very small, and at this time the emitter voltage and base voltage of Q65 are almost equal, and Q65 is in the off state.

[0072] When the target current is greater than or equal to the first threshold, the voltage drop across the sampling resistor circuit increases, and the voltage across R707 decreases, resulting in a voltage drop across the emitter and base of Q65, thus turning Q65 on. After Q65 turns on, its collector outputs a valid trigger signal, the electrical characteristics of which are set to drive the first transistor Q68 in the subsequent first protection unit into the on state.

[0073] The protection unit includes a positive feedback self-locking loop consisting of Q68 and the second transistor Q64.

[0074] The base of Q68 receives the trigger signal through the second current-limiting resistor R806. A first pull-down resistor R809 is connected between the base of Q68 and GND. R809 and R806 form a voltage divider circuit to attenuate and adjust the level of the trigger signal from the collector of Q65. By setting the resistance ratio of R806 and R809 (the specific ratio depends on the situation and is not limited here), the base current and voltage required to drive Q68 to conduct can be precisely controlled, and the base of Q68 is ensured to be at a low level when there is no trigger signal, thus enhancing the anti-interference capability.

[0075] The emitter of Q68 is grounded. The collector of Q68 is connected to the base of Q64 through the third current-limiting resistor R800. The emitter of Q64 is connected to VBAT. Its collector is connected back to the base of Q68 through a unidirectional diode D189 (the anode is connected to the collector of Q64, and the cathode is connected to the base of Q68 through R806), forming a positive feedback path.

[0076] D188 acts as a one-way valve in the self-locking loop, ensuring that the positive feedback signal can only flow from Q64 to Q68, preventing logic races during reset or power-on, thereby ensuring the reliability and directionality of the self-locking action.

[0077] After the first trigger signal is divided by R806 and R809, the base of Q68 receives a sufficient voltage to turn on. Once Q68 turns on, it drives Q64 to turn on. When Q64 turns on, its collector outputs a new trigger signal, which is positively fed back to the base of Q68 through D189 and R806. Even if the original trigger signal disappears at this point, this new trigger signal can maintain the conducting state of Q68 and Q64, achieving self-locking. In the self-locking state, the collector of Q64 continuously outputs a valid first control signal to the gate (G) of power switch Q62, turning it off.

[0078] The protection unit also includes a reset transistor Q63 and a first bias resistor R706.

[0079] The base of reset transistor Q63 receives the reset signal; the emitter of Q63 is connected to VBAT, and its collector is connected to the base of Q64. R706 is connected between VBAT and the base of Q64. Its function is to provide a pull-up bias to the base of Q64 when there is no reset signal, ensuring its reliable turn-off; when there is a reset signal, it cooperates with the conducting Q63 to release the latch-up state.

[0080] Release process: When the reset signal is applied to the base of Q63, Q63 saturates and conducts. At this time, the base of Q64 presents a low-impedance path to VBAT through the conducting Q63. R706 and the conducting Q63 work together to strongly pull the base potential of Q64 up to near VBAT, thereby forcing Q64 to turn off. After Q64 turns off, the positive feedback loop is broken, Q68 turns off accordingly, and the self-locking state is completely released. If the overcurrent fault has disappeared at this time, the circuit will return to normal operation.

[0081] In one embodiment, exemplarily illustrated, such as Figure 2 As shown, the overcurrent protection device also includes a reset signal source 25. The input terminal of the reset signal source 25 is connected to the voltage output terminal of the power supply module 24 to obtain a stable operating voltage; the output terminal of the reset signal source 25 is connected to the first overcurrent protection module 22 (and...). Figure 6 The base of Q63 (as shown) is connected to periodically provide a reset signal to the first overcurrent protection module 22.

[0082] In this invention, the reset signal source 25 is a self-excited oscillation circuit, such as a pulse-width modulation (PWM) oscillation circuit, a multivibrator circuit composed of a relaxation oscillator, a crystal oscillator, and an integrated circuit timer, or a ring oscillation circuit composed of gate circuits, etc. Furthermore, in a system containing a processor, the reset signal source 25 can also be generated by the processor's timer module or a general-purpose input / output interface. Any circuit or unit capable of providing periodic reset probe pulses falls within the scope of the reset signal source 25 of this invention.

[0083] like Figure 7 The diagram shown is a schematic of the circuit structure of the reset signal source 25 in one embodiment. In this circuit, a PWM oscillation circuit is used as the reset signal source 25. The PWM oscillation circuit is connected to the voltage output terminal in the power supply module 24 and includes at least an astable multivibrator composed of a first oscillation transistor Q71 (NPN type transistor) and a second oscillation transistor Q72 (NPN type transistor). Its function is to generate continuous square wave oscillations through self-excitation.

[0084] In this circuit, the emitters of both Q71 and Q72 are connected to GND. The collector of Q71 is connected to the base of Q72 via a first timing circuit (a first resistor R803, a second resistor R804, and a third capacitor C464). Correspondingly, the collector of Q72 is connected to the base of Q71 via a second timing circuit (a third resistor R805, a fourth resistor R802, and a fourth capacitor C463).

[0085] Q71, the first timing circuit, Q72, and the second timing circuit constitute a typical positive feedback cross-coupled circuit. If Q71 is on and Q72 is off, the collector of Q71 is at a low level. C464 discharges through R803 and R804, attempting to pull down the base voltage of Q72. Simultaneously, the power supply module 24 charges C463, pulling up the base voltage of Q71. After a delay determined by the time constants of R805, R802, and C463, the base voltage of Q71 reaches its conduction threshold, and Q71 transitions from on to off, its collector switching to a high level. This transition is coupled through C464, giving the base of Q72 a positive pulse and causing it to quickly conduct. After Q72 conducts, its collector becomes low, and this change is coupled through C463, pulling down the base voltage of Q71 and maintaining it in the off state. The circuit then enters another steady state (Q71 off, Q72 on). This process repeats continuously, generating a continuous square wave signal (PWM wave) at the collector of Q71 or Q72. By adjusting the resistance values ​​of R802 and R804, the charging and discharging time of the capacitor can be changed, thereby precisely adjusting the oscillation frequency and duty cycle of the PWM wave.

[0086] The PWM oscillation circuit also includes a PWM control switch, which converts the PWM wave generated by the oscillator into a reset signal that can be used to release the self-lock.

[0087] The first control transistor (labeled Q67) uses an NMOS as the PWM control switch, and the PWM control switch also includes a second pull-down resistor R811.

[0088] In this circuit, the gate of Q67 serves as the control electrode, connected to the output of the PWM oscillation circuit (such as the collector of Q72), while its source is grounded. R811 is connected between the gate of Q67 and GND. Its core function is to provide a defined low-level reference potential for the gate of Q67, ensuring that the gate voltage of Q67 is reliably pulled low when the PWM wave is low or there is no signal. This prevents Q67 from being mistakenly turned on due to interference, enhancing the circuit's anti-interference capability and static stability.

[0089] The drain of Q67 is connected to the control terminal (base of Q63) of the reset switch device in the first overcurrent protection module 22 through the first driving circuit. The first driving circuit includes at least the fourth current limiting resistor R799 and the second bias resistor R705.

[0090] The first terminal of R799 is connected to the drain of Q67, and the second terminal of R799 is connected to the first terminal of R705. The base of Q63 is connected between the second terminal of R799 and the first terminal of R705, and the second terminal of R705 is connected to VBAT. Therefore, when Q67 is off, R705 provides a stable high level (VBAT) to the base of Q63, ensuring reliable turn-off and enhancing anti-interference capability. When Q67 is on, R799 and R705 form a voltage divider circuit, safely pulling the base voltage of Q63 down to the level required for saturation conduction, while limiting current to protect both Q67 and Q63.

[0091] When the PWM wave is in a low-level period: the gate-source voltage of Q67 is lower than its turn-on threshold, and Q67 is in the off state.

[0092] When the PWM wave is in a high-level period: the gate-source voltage of Q67 is higher than its turn-on threshold, and Q67 quickly saturates and turns on. The drain of Q67 is forcibly pulled low to near ground potential. This action generates a low-level pulse. For the PNP type Q63, the low base voltage (relative to its emitter connected to VBAT) reaches its turn-on threshold. Therefore, this low-level pulse acts as a reset signal, driving Q63 to turn on momentarily, thereby pulling up the voltage of the critical node (base of Q64) in the self-locking loop of the first overcurrent protection module 22, forcibly releasing the self-locking state.

[0093] Based on the above device, the reset signal source 25 powered by the power supply 10 can periodically and automatically provide a reset signal to the first overcurrent protection module 22, thereby ensuring that after a minor overcurrent protection occurs, the system can periodically and automatically attempt to clear the self-locking state and restore power supply without external intervention, which greatly improves the self-recovery capability and operational continuity of the equipment under non-fatal failures.

[0094] In one embodiment, the second overcurrent protection module 23 includes, but is not limited to, a second voltage divider resistor and a second trigger transistor, wherein the resistance value of the second voltage divider resistor is less than the resistance value of the first voltage divider resistor.

[0095] The first end of the second voltage divider resistor is connected between the sampling resistor of the current detection module 21 and the power switch 20, and the second end of the second voltage divider resistor is connected to the control electrode of the second trigger transistor; the first main electrode of the second trigger transistor is connected to the reference potential; and the second main electrode of the second trigger transistor is connected to the power switch 20.

[0096] The second voltage divider resistor, connected in series with the sampling resistor in the current detection module 21, forms a second voltage divider circuit (a second threshold is set by adjusting the resistance value of the second voltage divider resistor). This circuit is used to turn on the second trigger transistor when the target current is greater than or equal to the second threshold, and output a second control signal through the second main electrode of the second trigger transistor to turn off the power switch 20. The specific limitations of the second trigger transistor are the same as those of the first trigger transistor, and will not be repeated here.

[0097] like Figure 8 The diagram shown is a schematic diagram of the circuit structure of the second overcurrent protection module 23 in one embodiment. In this circuit, a PMOS is used as the power switch 20 (marked as Q62), and a PNP transistor is used as the second trigger transistor (marked as Q69).

[0098] The second overcurrent protection module consists of a second voltage divider resistor R808 and Q69. The first terminal of R808 is connected to the output of the sampling resistor circuit (R667, R670, R704), and the second terminal of R808 is connected to the base of Q69. The emitter of Q69 is connected to the input of the sampling resistor circuit, and its collector serves as the output of the second detection unit, connected to the gate (labeled G) of Q62. Simultaneously, a first pull-up resistor R807 is connected between the base and emitter of Q69. The output of the sampling resistor circuit (R667, R670, R704) is also connected to the source (labeled S) of Q62.

[0099] When the target current does not exceed the second threshold, the voltage drop across the sampling resistor circuit is low, making the voltage division across R808 insufficient to turn on Q69. At this time, R807 stably pulls the base potential of Q69 up to near the emitter potential, thereby ensuring that Q69 is reliably in the off state and avoiding false triggering due to interference or leakage current.

[0100] Only when the target current exceeds the second threshold does the voltage drop across the sampling resistor circuit increase significantly (because the resistance of R808 is relatively small, its voltage division is also low, so a larger current is needed to generate a sufficient voltage drop across R808). When this voltage drop reaches the base-emitter turn-on threshold of Q69 (approximately 0.6-0.7V), Q69 turns on, and its collector output is used to turn off the second control signal of Q62.

[0101] Based on the above device, a second voltage divider circuit is formed by using a second voltage divider resistor with a smaller resistance value and a sampling resistor. A higher current detection threshold (second threshold) is set, and a second trigger transistor is used as a fast response device. When a severe overcurrent or short circuit is detected, it can bypass the self-locking logic of the first stage and directly and quickly output a control signal to the power switch to force it to shut down. This provides the system with ultimate hardware protection against catastrophic failures that is fast-responding and cannot be automatically recovered.

[0102] In one embodiment, exemplarily illustrated, such as Figure 2 As shown, in order to drive and protect the power switch 20 and prevent its gate voltage from being damaged due to abnormal reasons (such as voltage spikes, noise coupling, etc.), the overcurrent protection device 11 may also include an isolation module 26. The input terminal of the isolation module 26 is connected to the output terminals of the first overcurrent protection module 22 and the second overcurrent protection module 23, and the output terminal of the isolation module 26 is connected to the control electrode of the power switch 20.

[0103] The isolation module 26 is used to receive the first control signal output by the first overcurrent protection module 22 and / or the second control signal output by the second overcurrent protection module 23, and convert the first control signal and / or the second control signal into a drive signal to turn off the power switch 20.

[0104] Based on the above device, the control signals output by the first overcurrent protection module 22 and / or the second overcurrent protection module 23 are isolated by the isolation module 26 and converted into signals that directly drive the power switch 20 to turn off, thereby improving the response speed and reliability of the overcurrent protection and ensuring that the power switch 20 can be turned off quickly and safely in case of a fault.

[0105] In one embodiment, exemplarily illustrated, the isolation module 26 includes at least a third switching device and a driving switching device, typically employing a complementary transistor type combination. Complementarity means that an N-type device (such as an NPN transistor or NMOS) is paired with a P-type device (such as a PNP transistor or PMOS). This combination naturally achieves signal inversion and level shifting, representing the most classic and reliable circuit structure for efficient driving and level conversion from the low-voltage logic side to the high-voltage power side. The device type of the third switching device is determined by the output characteristics of the first overcurrent protection module 22 and the second overcurrent protection module 23 to ensure electrical compatibility and logical coherence throughout the signal chain.

[0106] The control terminal of the third switching device is connected to the output terminals of the first overcurrent protection module 22 and the second overcurrent protection module 23, and is used to turn on in response to the first control signal or the second control signal; the first conducting terminal of the third switching device is connected to the first reference potential; the second conducting terminal of the third switching device is connected to the control terminal of the driving switching device; the first conducting terminal of the driving switching device is connected to the second reference potential, and the second conducting terminal of the driving switching device is connected to the control electrode of the power switch 20; wherein, the first reference potential and the second reference potential are two different DC potential nodes, such as GND+VBAT and VBAT+GND.

[0107] The driving switch device is configured to turn on in response to the turn-on of the third switch device and output the voltage of the second reference potential as a driving signal to the control electrode of the power switch 20 to turn off the power switch 20.

[0108] like Figure 9 The diagram shows a circuit structure of isolation module 26 in one embodiment. In this circuit, an NMOS is used as the third switching device (labeled Q70), which, together with a PNP transistor as the driving switching device (labeled Q66), forms a complementary driving stage. Its core function is to receive the protection command from the previous stage and safely and forcefully drive Q62 to turn off.

[0109] The gate of Q70 is connected to the collector of Q64 in the first overcurrent protection module 22 and the collector of Q69 in the second overcurrent protection module 23. The source of Q70 is connected to GND. At the same time, a third pull-down resistor R812 is connected between the gate of Q70 and GND. Its core function is to provide a certain low-level reference potential for the gate of Q70, ensuring that the gate voltage of Q70 is reliably pulled low when there is no effective control signal. This effectively prevents false turn-on caused by gate voltage fluctuations due to spatial electromagnetic interference or line coupling noise, and greatly enhances the anti-interference capability and stability of the circuit under static conditions.

[0110] The drain of Q70 is connected to the base of Q66 through a second driving circuit, wherein the second driving circuit includes at least a fifth current-limiting resistor R801 and a third bias resistor R798.

[0111] The first terminal of R801 is connected to the drain of Q70, and the second terminal of R801 is connected to the first terminal of R798. The base of Q66 is connected between the second terminal of R801 and the first terminal of R798, and the second terminal of R798 is connected to VBAT. The emitter of Q66 is connected to VBAT, and the collector of Q66 is connected to the gate (G) of Q62. Furthermore, the collector of Q66 is also connected to GND through the sixth current-limiting resistor R810.

[0112] Based on the above connection, when Q70 is turned off, its drain is in a high-resistivity state. At this time, VBAT is directly pulled up to near VBAT via R798, bringing the base potential of Q66 close to VBAT. This ensures that the base potential and emitter potential of Q66 are almost equal, guaranteeing that Q66 is reliably off and providing a stable DC bias to its base, further enhancing its anti-interference capability. Simultaneously, R810 provides a clear pull-down path to GND for the gate of Q62, ensuring that its gate potential is 0V when undriven, preventing Q62 from being in an uncertain state due to a floating gate.

[0113] When Q70 is turned on, it enters saturation conduction, and its drain potential is pulled down to near ground level (approximately 0.1-0.2V). At this time, VBAT, R798, R801, and the turned-on Q70 form a voltage divider circuit. R801 is a critical current-limiting resistor, whose function is to limit the current from VBAT through R798, the base-emitter junction of Q66, and Q70 to GND, preventing excessive current from damaging Q70 or Q66. Simultaneously, this voltage divider circuit safely and controllably pulls the base voltage of Q66 down to a sufficiently low level (far below VBAT), thereby providing the base drive current and voltage required for Q66 to enter saturation conduction.

[0114] When Q66 is turned on, a low-impedance path is established between its collector and emitter. This path can provide a large instantaneous current to quickly and forcefully pull up the gate voltage of Q62, thereby reliably and quickly turning off Q62.

[0115] Based on the above device, the isolation module 26, which consists of a third switching device and a driving switching device, realizes the generation and transmission of a turn-off drive signal by utilizing the voltage difference between two different DC reference potentials. This not only effectively realizes the electrical isolation between the front and rear circuits and enhances the anti-interference capability, but also ensures the amplitude and stability of the drive signal, thereby reliably and quickly turning off the power switch 20.

[0116] In one embodiment, exemplarily illustrated, such as Figure 2 As shown, the overcurrent protection device 11 also includes an overvoltage protection module 27, which is connected in parallel across the two ends of the power switch 20, and more specifically, between the first main electrode and the control electrode of the power switch 20.

[0117] The overvoltage protection module 27 is used to clamp the voltage between the control electrode of the power switch 20 and the first main electrode within a preset safe value (determined according to the maximum voltage between the control electrode of the power switch 20 and the first main electrode, and its specific value must be less than and close to this maximum voltage).

[0118] Based on the above-mentioned device, the overvoltage protection module 27 can effectively prevent the power switch 20 from being damaged by voltage spikes or abnormal overvoltage, thereby improving the reliability and durability of the circuit.

[0119] In one embodiment, the overvoltage module 26 is illustrated by way of example, including but not limited to a voltage clamping unit and a current limiting unit; wherein the voltage clamping unit and the current limiting unit are connected in parallel to form a protection branch, and the protection branch is connected in parallel between the first main electrode and the control electrode of the power switch 20.

[0120] The voltage clamping unit is used to conduct when the voltage between the first main electrode and the control electrode of the power switch 20 exceeds a preset safety value, so as to perform voltage clamping; the current limiting unit is used to limit the current flowing through the voltage clamping unit.

[0121] Based on the above device, a protection branch is formed by a voltage clamping unit and a current limiting unit connected in series, so that the power switch 20 can be quickly turned on for voltage clamping when an overvoltage occurs. At the same time, the current limiting unit effectively suppresses the inrush current during the clamping process, thereby achieving reliable overvoltage protection while avoiding damage to the protection element itself due to overcurrent.

[0122] In one embodiment, exemplarily illustrated, the voltage clamping unit includes at least one unidirectional or bidirectional voltage regulator, such as a second Zener diode or a transient voltage suppressor diode. The current limiting unit includes at least one resistor.

[0123] For example, a voltage clamping unit may include a single second Zener diode, or multiple second Zener diodes connected in parallel, either in the same or opposite direction, to accommodate overvoltage or power dissipation of different polarities. A current limiting unit may include a single resistor, or multiple resistors connected in series or in parallel to meet power or accuracy requirements.

[0124] like Figure 10 The diagram shown is a schematic of the circuit structure of the overvoltage protection module 27 in one embodiment. In this circuit, a PMOS is used as the power switch 20 (labeled Q62). The overvoltage protection module 27 is composed of a second Zener diode D188 and a seventh current-limiting resistor R796 connected in series. The cathode of D188 is connected to the source (S) of Q62, and the anode of D188 is connected to the gate (G) of Q62. The two ends of R796 are connected to the cathode and anode of D188, respectively.

[0125] When the gate voltage (G) of Q62 is lower than the source voltage (S) of Q62, D188 is in reverse bias (cathode at high potential S, anode at low potential G). Once this reverse voltage reaches and exceeds the breakdown voltage of D188, D188 will immediately enter the breakdown state, forcibly limiting the voltage difference between G and S within a preset safe value, thus protecting G from breakdown. Simultaneously, the resistor R796 connected in parallel with D188 can pre-divert overvoltage current, limiting its impact strength, protecting D188 and making the entire clamping process more stable and reliable. Together, these two mechanisms achieve rapid and effective protection against negative overvoltage at the control electrode of the power switch 20.

[0126] To clearly explain the circuit structure and working principle of the overcurrent protection device 11, the following is in conjunction with the appendix. Figures 4 to 9 The complete circuit implementation of the device is described below. The specific connection relationships and parameters of each electronic component in the device are shown in the corresponding figures.

[0127] like Figure 11 The diagram shows a circuit structure of overcurrent protection device 11 in one embodiment. In this circuit, during normal operation (load 12 current < preset threshold): VBAT enters the circuit through R797 and D75, where D75 provides a stable supply voltage; Q71 and Q72 oscillate to generate a PWM wave, which acts on Q67 to control its switching. When Q72 outputs a high level, Q67 conducts, creating a voltage drop across R705, causing Q63 to conduct. When load 12 does not experience overcurrent, the voltage drop across R667, R670, and R704 is low enough not to reach the conduction threshold of Q65, thus Q68 and Q64 do not conduct, the positive feedback self-locking loop does not work, and the PWM wave has no effect. During this process, the main circuit supplying power to load 12 flows from VBAT through R667, R670, and R704 to Q62, and is then output to load 12.

[0128] During a slight overcurrent (first threshold ≤ load current < second preset threshold): the voltage drop across R667, R670, and R704 increases. At this time, the voltage drop across the first voltage divider circuit formed by the sampling resistor circuit (R667, R670, R704) and R707 increases, so Q65 conducts. Since R808 has a smaller resistance than R707, Q69 does not conduct at this time.

[0129] After Q65 turns on, a voltage drop is formed in the R806 and R809 circuit, so Q68 turns on. At this time, a circuit is formed in the R706, R800, and Q68, and a voltage drop is generated in R706, causing Q64 to turn on. At this time, a voltage drop is formed in the circuit Q64 and R812, causing Q70 to turn on. A voltage drop is formed in the circuit (R798, R801, Q70), causing Q66 to turn on. At this time, the gate and source voltages of Q62 are close enough to be insufficient to turn on, so there is no input to load 12.

[0130] At this point, if the slight overcurrent disappears and Q65 turns off, the conduction of Q64 will cause Q68 to conduct, creating a latch-up. However, when the PWM wave is high, Q67 turns on, creating a voltage drop across R705, R799, and Q67, causing Q63 to conduct. Since Q63 and R706 are connected in parallel, the voltage drop across R706 at this time is the voltage drop at which Q63 saturates and conducts, which is insufficient to turn on Q64. At this point, the latch-up is released, and the circuit returns to normal operation.

[0131] Under severe overcurrent conditions (load current ≥ second preset threshold): The voltage drop across R667, R670, and R704 is very large, creating a voltage drop across the sampling resistor circuit (R667, R670, R704) and R808, causing Q69 to conduct. At this time, the voltage drop across the loop (Q69, R812) causes Q70 to turn on, and the voltage drop across the loop (R798, R801, Q70) causes Q66 to turn on. Since the gate and source voltages of Q62 are too close to be sufficient for conduction, there is no input to load 12. Whether the self-locking loop is working at this time does not affect the opening and closing of Q62.

[0132] Based on the above device, in the event of a minor overcurrent, the first overcurrent protection module provides intelligent protection with automatic recovery, preventing accidental shutdown due to momentary overload and improving equipment availability. In the event of a severe overcurrent, the second overcurrent protection module implements rapid and irreversible hard shutdown protection, ensuring absolute system safety. The entire protection process is completed automatically by the hardware circuit without software intervention, improving the intelligence and reliability of the equipment while reducing implementation costs.

[0133] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An overcurrent protection device, connected between a power supply and a load, characterized in that, The device includes: A power switch is connected in series between the power source and the load. A current detection module is used to detect the target current flowing from the power source to the load; A first overcurrent protection module, connected to the current detection module and the power switch, is used to trigger a self-locking mechanism to turn off the power switch when the target current is greater than or equal to a first threshold, wherein the self-locking mechanism can be released in response to a reset signal.

2. The apparatus according to claim 1, characterized in that, The device also includes a second overcurrent protection module, which is connected to the current detection module and the power switch; The first overcurrent protection module is used to trigger the self-locking to turn off the power switch when the target current is greater than or equal to a first threshold and less than a second threshold. The second overcurrent protection module is used to directly turn off the power switch when the target current is greater than or equal to the second threshold.

3. The apparatus according to claim 1, characterized in that, The current detection module includes at least one sampling resistor, which is connected in series between the power supply and the power switch to generate a voltage drop signal proportional to the target current. The current detection module obtains the target current by detecting the voltage drop signal.

4. The apparatus according to claim 1, characterized in that, The first overcurrent protection module includes at least: A detection unit, connected to the current detection module, is used to output a trigger signal when the target current is greater than or equal to the first threshold. A protection unit, connected to the detection unit and the power switch, is configured to trigger a self-locking mechanism in response to the trigger signal, output a first control signal to turn off the power switch, and release the self-locking mechanism in response to the reset signal.

5. The apparatus according to claim 4, characterized in that, The detection unit includes at least a first voltage divider resistor and a first trigger transistor; The first end of the first voltage divider resistor is connected between the sampling resistor of the current detection module and the power switch; the second end of the first voltage divider resistor is connected to the control electrode of the first trigger transistor; the first main electrode of the first trigger transistor is connected to the reference potential. The first voltage divider resistor and the sampling resistor in the current detection module are connected in series to form a first voltage divider circuit, which is used to turn on the first trigger transistor when the target current is greater than or equal to the first threshold, and output the trigger signal through the second main electrode of the first trigger transistor.

6. The apparatus according to claim 4, characterized in that, The protection unit includes at least a first switching device, a second switching device, and a reset switching device; the first conducting terminals of the first switching device, the second switching device, and the reset switching device are connected to a reference potential. The control terminal of the first switching device is connected to the detection unit and is used to turn on in response to the trigger signal; The second conducting terminal of the first switching device is connected to the control terminal of the second switching device, and the second conducting terminal of the second switching device is connected to the control terminal of the first switching device, so that the first switching device and the second switching device form a positive feedback self-locking loop. The control terminal of the reset switch device is used to receive the reset signal, and the second conducting terminal of the reset switch device is connected to the control terminal of the second switch device, and is used to conduct in response to the reset signal to release the positive feedback self-locking loop; The protection unit outputs the first control signal through the second conducting terminal of the second switching device.

7. The apparatus according to claim 6, characterized in that, The first switching device, the second switching device, and the reset switching device are all bipolar junction transistors; The control terminal corresponds to the base, the first conducting terminal corresponds to the emitter, and the second conducting terminal corresponds to the collector.

8. The apparatus according to claim 1, characterized in that, The device further includes a reset signal source connected to the first overcurrent protection module. The reset signal source is a self-excited oscillation circuit used to generate the periodic reset signal.

9. The apparatus according to claim 2, characterized in that, The second overcurrent protection module includes at least: a second voltage divider resistor and a second trigger transistor; the resistance value of the second voltage divider resistor is less than the resistance value of the first voltage divider resistor; The first end of the second voltage divider resistor is connected between the sampling resistor of the current detection module and the power switch, and the second end of the second voltage divider resistor is connected to the control electrode of the second trigger transistor. The first main electrode of the second trigger transistor is connected to the reference potential, and the second main electrode of the second trigger transistor is connected to the power switch; The second voltage divider resistor and the sampling resistor in the current detection module are connected in series to form a second voltage divider circuit, which is used to turn on the second trigger transistor when the target current is greater than or equal to the second threshold, and output a second control signal through the second main electrode of the second trigger transistor to turn off the power switch.

10. The apparatus according to claim 1, characterized in that, The power switch is a field-effect transistor; The first main electrode of the power switch is connected to the current detection module, the second main electrode of the power switch is connected to the load, and the control electrode of the power switch is connected to the first overcurrent protection module and the second overcurrent protection module. The first control signal and the second control signal are used to adjust the control electrode voltage of the power switch to a preset shutdown threshold to turn off the power switch.

11. The apparatus according to claim 2, characterized in that, The device further includes an isolation module, which is connected between the output terminals of the first overcurrent protection module and the second overcurrent protection module and the control electrode of the power switch. The isolation module is used to receive a first control signal output by the first overcurrent protection module and / or a second control signal output by the second overcurrent protection module, and convert the first control signal and / or the second control signal into a drive signal to drive the power switch to turn off.

12. The apparatus according to claim 11, characterized in that, The isolation module includes at least a third switching device and a driving switching device; The control terminal of the third switching device is connected to the output terminals of the first overcurrent protection module and the second overcurrent protection module, and is used to turn on in response to the first control signal or the second control signal; the first conducting terminal of the third switching device is connected to the first reference potential. The second conducting terminal of the third switching device is connected to the control terminal of the driving switching device; the first conducting terminal of the driving switching device is connected to the second reference potential, and the second conducting terminal of the driving switching device is connected to the control electrode of the power switch. Wherein, the first reference potential and the second reference potential are two different DC potential nodes; The driving switch device is configured to turn on in response to the turn-on of the third switch device, and output the voltage of the second reference potential as the driving signal to the control electrode of the power switch to turn off the power switch.

13. The apparatus according to claim 10, characterized in that, The device also includes an overvoltage protection module, which is connected between the first main electrode and the control electrode of the power switch. The overvoltage protection module is used to clamp the voltage between the control electrode of the power switch and the first main electrode within a preset safety value.

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