Electronic fuse circuit connected in series in the power path
By employing a dual positive feedback avalanche shutdown mechanism and a multi-circuit collaborative design, the problems of slow response speed, low accuracy, and malfunction in traditional circuit protection schemes are solved, achieving fast and accurate circuit protection and self-locking functions, which are suitable for various power supply systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGGUAN WORDOP AUTOMATION TECH
- Filing Date
- 2026-04-21
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional circuit protection schemes have slow response speed, low protection threshold accuracy, are prone to false triggering, cannot distinguish between surges and real faults, cannot be quickly reset, and are not convenient for integrated use.
It employs a dual positive feedback avalanche shutdown mechanism, a voltage regulated power supply circuit, a threshold reference circuit, a power switch and current sampling circuit, a shaping filter circuit, a power-on reset circuit, a comparison control circuit, and a reserved control reset interface to achieve microsecond-level overcurrent shutdown, self-locking protection, and fault indication.
It achieves fast response, precise protection, anti-maloperation, self-locking function, resettableness, and compatibility with capacitive/inductive loads, reducing the risk of safety accidents and maintenance difficulty, and is suitable for various power supply systems.
Smart Images
Figure CN122393857A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic circuit protection technology, and in particular to an electronic fuse circuit connected in series in the power supply path. Background Technology
[0002] Traditional circuit protection commonly uses fuses and PTC resettable fuses, which have significant drawbacks: First, they have slow response speeds and cannot shut off in time after overcurrent, easily causing damage to downstream chips and power devices, and even leading to safety accidents such as fires and smoke. Second, the protection threshold accuracy is low and has large dispersion, making it unsuitable for precision loads. Third, they cannot distinguish between surges and real faults, and are prone to false tripping with capacitive and inductive loads. Fourth, traditional solutions generally do not include the internal resistance of power transistors, resulting in inaccurate protection ranges and a tendency for untimely or over-protection. Fifth, they cannot be quickly reset after tripping, making maintenance inconvenient and hindering integrated and intelligent use.
[0003] Therefore, there is an urgent need for an electronic fuse that is fast-responding, highly accurate, does not malfunction, is self-locking, and expandable to achieve reliable circuit protection. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-speed, high-precision, anti-maloperation electronic fuse circuit with self-locking protection. It can be connected in series in the negative or positive power path to achieve microsecond-level overcurrent shutdown, is compatible with capacitive / inductive loads, and the protection point includes the equivalent internal resistance of the power transistor. The safety range is more reasonable, and it supports fault indication, external reset and switch multiplexing.
[0005] In a first aspect, embodiments of this application provide an electronic fuse circuit connected in series in the power supply path, comprising: a voltage regulator circuit, a threshold reference circuit, a power switch and current sampling circuit, a shaping filter circuit, a power-on reset circuit, a comparison control circuit, a dual positive feedback circuit, and a reserved control reset interface; the power switch and current sampling circuit connects the power transistor and the sampling resistor in series in the main power supply path, and the sampling voltage includes the common voltage drop of the sampling resistor and the equivalent internal resistance of the power transistor; the comparison control circuit compares the sampling voltage with the set voltage of the threshold reference circuit and outputs a control level to drive the power transistor to turn on or off; the dual positive feedback circuit forms a two-stage linked avalanche reversal when overcurrent is triggered, causing the power transistor to be quickly locked off; the power-on reset circuit is used to initialize the circuit to the off state at the moment of power-on, and enters normal conduction after completing soft start; the reserved control reset interface is used for external reset or as a power switch control.
[0006] In one embodiment, when the power path is a negative path, the power transistor is an N-MOS transistor; wherein, when the circuit is working normally, the power transistor remains on, and when there is an overcurrent, the sampling voltage rises, the comparator control circuit flips and quickly turns off the N-MOS transistor and latches it through double positive feedback.
[0007] In one embodiment, when the power path is a positive path, the power transistor is a P_MOS transistor; when the circuit is working normally, the power transistor remains on; when there is an overcurrent, the sampling voltage changes in the reverse direction, the comparison control circuit flips and quickly turns off the P_MOS transistor and latches it through double positive feedback.
[0008] In one embodiment, the dual positive feedback circuit includes: First positive feedback: Changes in the comparator output pull down / up the threshold voltage, accelerating the comparator switching; Second positive feedback: The power transistor is turned off, which increases its equivalent internal resistance, further increasing the sampling voltage and continuously driving the latch-off. Two positive feedback loops work together to achieve avalanche-style rapid shutdown, with the fastest shutdown time being ≤0.001s.
[0009] In one embodiment, the power-on reset circuit is configured such that: at the moment of power-on, a capacitor provides an instantaneous reset level, causing the power transistor to be initially turned off; after the capacitor is fully charged, the reset is automatically released, and the circuit enters the normal operating range, avoiding false protection due to power-on surge.
[0010] In one embodiment, a fault indication circuit is further included: the fault indication circuit consists of an LED and a current limiting element; wherein the fault indication circuit is illuminated when the protection is activated, and the fault indication circuit is used to indicate an overcurrent fault status.
[0011] In one embodiment, the sampling resistor is composed of multiple resistors connected in parallel, and the protection current threshold can be adjusted by configuring the resistance value; the threshold reference circuit outputs a stable reference voltage to achieve high-precision overcurrent determination.
[0012] In one embodiment, the reserved control reset interface supports external signal reset, which can release the latch without power loss; or, in conjunction with external control, the electronic fuse can be used as a controllable power switch.
[0013] Secondly, embodiments of this application also provide an electronic fuse protection method, which includes the following steps: S1: Power-on reset, the circuit is initially shut down, and after soft start, the power transistor is turned on to enter normal power supply; S2: Real-time acquisition of the total voltage drop between the sampling resistor connected in series in the power path and the equivalent internal resistance of the power transistor; S3: Compare the collected voltage with the set threshold, and keep it conducting under normal conditions; S4: Triggers double positive feedback during overcurrent, causing the comparator to avalanche flip, quickly turning off the power transistor and latching the protection state; S5: After troubleshooting, power on again or reset via external interface to restore normal operation.
[0014] In one embodiment, the overcurrent level determines the turn-off speed. The circuit sets the minimum blanking time through LED clamping to accommodate the peak starting current of capacitive and inductive loads and avoid malfunctions.
[0015] The electronic fuse circuit provided by this invention has the following significant advantages compared with the prior art: 1. Extremely fast overcurrent response speed, significantly improved protection capability. This invention employs a dual positive feedback avalanche shutdown mechanism. After overcurrent triggering, the circuit can complete shutdown latching within 0.001 seconds (1ms), which is much faster than the response speed of traditional fuses, which is in the range of seconds or even hundreds of milliseconds. It can completely cut off the power supply before the load or downstream circuit is damaged, fundamentally avoiding safety accidents such as device burnout, smoke, and fire.
[0016] 2. High protection accuracy and stable threshold, suitable for precision circuit protection. This invention provides a stable reference threshold through a high-precision voltage regulator circuit and a reference voltage circuit, resulting in small protection point errors. At the same time, the current sampling includes the equivalent internal resistance of the power transistor itself, ensuring that the protection point falls within the safe operating range of the power transistor. This prevents protection failure due to the power transistor overheating or overload, making the protection more accurate and safer.
[0017] 3. Strong anti-interference capability, no malfunction, compatible with capacitive / inductive loads. This invention sets up an RC filter shaping circuit + LED clamping blanking time, which can effectively avoid the inrush current of capacitive loads and the instantaneous peak current of inductive loads, and avoid false protection during normal startup; at the same time, it can be flexibly adapted to different load characteristics through parameter configuration, achieving the optimal balance between "fast protection" and "no false triggering".
[0018] 4. Equipped with self-locking protection function, preventing repeated impacts after a fault. When the overcurrent protection is triggered, the circuit automatically locks itself in the off state through dual positive feedback and capacitor energy storage, preventing repeated conduction and repeated impacts. This avoids secondary damage caused by continuous power supply under fault conditions and improves system safety and reliability.
[0019] 5. Soft start upon power-on, no impact or surge, smoother protection. This invention incorporates a power-on reset circuit that forces the power transistor to be in a turned-off state at the moment of power-on and automatically turns it on again after the circuit stabilizes, thus achieving soft start. This avoids false protection or device impact caused by surge current at the moment of power-on and improves circuit lifespan.
[0020] 6. Fault status is visualized, facilitating maintenance and troubleshooting. The circuit integrates an LED fault indicator. The LED stays on when the protection is activated, providing a clear indication of overcurrent faults and facilitating quick problem location, significantly reducing on-site maintenance difficulty and troubleshooting time.
[0021] 7. Can be connected in series in the positive or negative power path, making it highly versatile. This invention provides two topologies: negative series (N-MOS) and positive series (P-MOS), which can be flexibly selected according to the system power supply architecture. The electronic fuse function can be realized without changing the main circuit of the system. It is applicable to various DC systems such as power modules, battery power supply, vehicle power supply, and industrial control.
[0022] 8. No component replacement required, can be reset and reused, resulting in low operating costs. Compared with traditional disposable fuses, this invention is an electronic resettable protection. After troubleshooting, it can be restored to work by powering on or resetting through an external interface. No parts need to be replaced, and it is more cost-effective and environmentally friendly in the long run.
[0023] 9. It has an expansion function and can also be used as a power switch. This invention provides an external reset / control interface, which can be connected to external buttons and MCU control signals to achieve fault reset without power loss. It can even use electronic fuses directly as controllable electronic switches to achieve integrated protection and control.
[0024] 10. The circuit structure is simple, low-cost, easy to mass-produce, and highly reliable. It uses all common resistors, capacitors, MOSFETs, comparators and other general-purpose components, without expensive dedicated chips. The circuit structure is simple, compact, and highly stable, making it suitable for mass production and embedded integration. Attached Figure Description
[0025] Figure 1 This is a flowchart illustrating the dual positive feedback operation of the negative electrode series-connected electronic fuse overcurrent protection according to the present invention; Figure 2 This is a circuit diagram of the negative electrode series-connected electronic fuse of the present invention; Figure 3 This is a flowchart illustrating the dual positive feedback operation of the positive electrode series-connected electronic fuse overcurrent protection according to the present invention; Figure 4 This is a circuit diagram of the positive electrode series-connected electronic fuse of the present invention. Detailed Implementation
[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0027] It should be noted that when a component is said to be "mounted on" another component, it can be directly mounted on the other component or may be interspersed with a component. When a component is said to be "set on" another component, it can be directly set on the other component or may be interspersed with a component. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or may be interspersed with a component.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.
[0029] Please see Figures 1 to 3 The electronic fuse circuit described in this invention, whether connected in series in the negative or positive power path, consists of the following eight functional modules: a voltage regulator circuit, a threshold reference circuit, a power switch and current sampling circuit, a shaping and filtering circuit, a power-on reset circuit, a comparison control circuit, a dual positive feedback circuit, a fault indication circuit, and a reserved reset interface. Each module works in concert to achieve power-on soft start, normal conduction power supply, overcurrent fast shutdown, self-locking protection, fault indication, and reset functions. Example 1
[0030] Please see Figure 1 and Figure 2 When the electronic fuse is connected in series on the negative power path, it consists of the following eight functional modules: a voltage regulator circuit, a threshold reference circuit, a power switch and current sampling circuit, a shaping and filtering circuit, a power-on reset circuit, a comparison control circuit, a dual positive feedback circuit, a fault indication circuit, and a reserved reset interface; among which, Each module works in concert to achieve soft start upon power-on, normal power supply, overcurrent fast shutdown, self-locking protection, fault indication, and reset functions. Power transistor Q2 is an N-MOS transistor, with its source or drain connected in series in the main negative circuit of the power supply. The sampling resistor is composed of R3, R4, and R5 connected in parallel, forming a series sampling structure with Q2 (N-MOS transistor). The total sampling voltage equals the voltage drop across the sampling resistor plus the voltage drop across Q2's on-resistance. The voltage regulator circuit consists of R1, R2, D1, D2, C1, C2, C3, and Q1, providing a stable 12V output to the control circuit. The threshold reference circuit consists of R15, R16, R17, R18, C9, and U2, providing a stable reference voltage of 0.158V. The comparator control circuit consists of R7, R8, C4, C5, and U1, which converts the sampling voltage... The voltage is compared with the reference voltage, and the output drives Q2 (N-MOS transistor); the shaping and filtering circuit consists of R11, R12, R13, C7, C8 and LED1, which filters, blanks and clamps the sampled signal; the power-on reset circuit consists of R9, R10, C6, C11, D3 and Q3, which realizes instantaneous shutdown upon power-on and conduction after soft start; the dual positive feedback circuit consists of R11, R12 and R18, which realizes avalanche fast shutdown in case of overcurrent; the reserved interface R14 is used for external reset or switch control.
[0031] When the negative power path is in normal operating condition, the power supply is normally powered on. The power supply regulator circuit, composed of R1, R2, D1, D2, C1, C2, C3, and Q1, provides regulated power to the electronic fuse circuit. The electronic fuse threshold circuit, composed of R15, R16, R17, R18, C9, and U2, provides a stable 0.158V voltage threshold. The fuse power-on reset circuit, composed of R9, R10, C6, C11, D3, and Q3, provides a positive voltage to pin 4 of the control circuit U1 through C6 when the power supply is on. This voltage peak is higher than 0.158V. At this time, the control voltage received by the fuse switching transistor is low, and the electronic fuse is in the open state at the moment of power-on. At the same time, the positive voltage provided by C6 is also provided to the gate of Q3, and Q3 is in the conducting state, which in turn activates C8. The capacitor voltage discharges to 0V; C6 forms the main charging circuit with R10 when powered on, and can be fully charged in about 0.002 seconds; due to the large capacity of C8, R11 and R12 charge it more slowly. At this time, R7 pulls the voltage of pin 4 of U1 to below the threshold voltage of 0.158V, so that the voltage of pin 1 of U1 changes from low to high, instantly rising to 12V. This voltage is supplied to the gate of Q2 (N-MOS transistor) through R6; the 12V high level of the gate will cause Q2 (N-MOS transistor) to enter the fully conducting state; the conduction of Q2 (N-MOS transistor) causes the charge of capacitor C8 by R11 and R12 to decrease rapidly and eventually stop; pin 4 of U1 remains below 0.158V, and the circuit is finally in a stable conducting state, thus continuously supplying power to the downstream protected circuit.
[0032] When the negative power supply path is in an abnormal operating state, the current of the protected circuit flows through the sampling resistors R3, R4, R5 and Q2 (N-MOS transistor). The parallel resistors R3, R4, and R5 are connected in series with the equivalent internal resistance of Q2 (N-MOS transistor) to form the total sampling resistor. The current flowing through this equivalent resistor will generate a voltage across it. This voltage will charge C7 through R12, and the voltage across C7 will then charge C8 through R11. Under normal conditions, the high voltage of C8 is less than 0.158V. When an overcurrent fault occurs in the protected circuit, the voltage generated across the sampling resistor to charge C8 is higher than 0.158V. This voltage is supplied to pin 4 of U1 through R7, because this voltage is higher than the threshold voltage of pin 3 of U1. At 158V, the voltage at pin 1 of U1 decreases, and this decrease in pin 1 pulls down the threshold voltage through resistor R18, forming the first positive feedback. The lower threshold voltage widens the voltage difference between pins 3 and 4 of U1, making pin 3 lower than pin 4, thus causing pin 1 of U1 to drop rapidly. Since the voltage at pin 1 of U1 is the control voltage of Q2 (N-MOS transistor), the decrease in the control voltage will increase the internal equivalent resistance of Q2 (N-MOS transistor), thus increasing the total sampling resistance. Because the equivalent resistance increases, the voltage formed by the current flowing through this resistor will also increase. This gradually increasing voltage charges C7 and C8 through R12 and R11, causing the voltage of C8 to gradually increase, forming the second positive feedback. Through the action of the first positive feedback UI and the second positive feedback, the circuit forms a two-way positive feedback circuit. The overall circuit quickly enters the avalanche reversal state, causing the output voltage of U1 to drop rapidly. Q2 (N-MOS transistor) is quickly turned off, and the voltage of C8 is charged and increased through R12 and R11. The voltage of C8 is led to pin 4 of U1 through R7, locking pin 1 of U1 to a low level. This locks the fuse, and the fuse is in the open state. The power supply to the protected circuit will be disconnected, and the circuit will eventually be in an abnormal working state.
[0033] When the negative power path is in the recovery state, disconnecting the power supply input and troubleshooting the protected circuit will cause the circuit to reset and supply power according to the normal operating procedure when the negative power path is in normal operation. If the protected circuit fault persists, the electronic fuse will repeat the procedure when the negative power path is in an abnormal operating state, disconnecting the circuit for protection. Example 2
[0034] Please see Figure 1 and Figure 3 When the electronic fuse is connected in series in the positive power path, it also consists of the following eight functional modules: voltage regulation circuit, threshold reference circuit, power switch and current sampling circuit, shaping and filtering circuit, power-on reset circuit, comparison control circuit, dual positive feedback circuit, fault indication circuit, and reserved reset interface; among which, The structure of the voltage regulator circuit, threshold reference circuit, shaping filter circuit, power-on reset circuit, comparison control circuit, and dual positive feedback and fault indication circuit is basically the same as that in Example 1, except that the voltage comparison logic is reversed. During overcurrent, the sampling voltage decreases, triggering the comparator to flip. All modules work together to achieve power-on soft start, normal power supply, overcurrent fast shutdown, self-locking protection, fault indication, and reset functions. Power transistors Q2 and Q3 are both P-MOS transistors, with their source or drain connected in series in the main positive circuit of the power supply. The sampling resistor consists of R3, R4, and R5. The circuit is configured in parallel, forming a series sampling structure with Q2. The total sampling voltage equals the voltage drop across the sampling resistor plus the voltage drop across the internal resistance of Q2 during conduction. This voltage regulator circuit consists of R1, R2, D1, D2, C1, C2, C3, and Q1, providing a stable 12V output to the control circuit. The threshold reference circuit consists of R15, R16, R17, R18, C9, and U2, providing a stable reference voltage of 0.158V. The comparison control circuit consists of R7... The circuit consists of R8, C4, C5, and U1, which compares the sampled voltage with the reference voltage and outputs to drive Q2. The shaping and filtering circuit consists of R11, R12, R13, C7, C8, and LED1, which filters, blanks, and clamps the sampled signal. The power-on reset circuit consists of R9, R10, C6, C11, D3, and Q3, which realizes instantaneous shutdown upon power-on and conduction after soft start. The dual positive feedback circuit consists of R11, R12, and R18, which realizes avalanche-type fast shutdown during overcurrent. The reserved interface R14 is used for external reset or switch control.
[0035] When the positive power path is in normal operating condition, the power supply regulator circuit composed of R1, R2, D1, D2, C1, C2, C3, and Q1 provides regulated power to the electronic fuse circuit. The electronic fuse threshold circuit, composed of R15, R16, R17, R18, C9, and U2, provides a stable -0.158V voltage threshold. The fuse power-on reset circuit, composed of R9, R10, C6, C11, D3, and Q2, provides a positive voltage to pin 4 of the control circuit U1 through C6 when the power is on. This voltage peak is higher than -0.158V, so the control voltage received by the fuse switch is low, and the fuse is in the open state at the moment of power-on. Simultaneously, the negative voltage provided by C6 is also supplied to the gate (G) of Q3, putting it in the conducting state and discharging the capacitor voltage of C8 to 0V. C6, together with R10, forms the main charging circuit upon power-on, completing charging in approximately 0.002 seconds. Because C8 has a large capacitance, R11 and R12 charge it slowly. At this time, R7 pulls the voltage at pin 4 of U1 above the threshold voltage of -0.158V, causing the output voltage at pin 1 of U1 to drop instantly from high to -12V. This voltage is supplied to the gate (G) of Q2 through R6. Q2 is a P-MOSFET, and the -12V level at its gate will cause Q2 to enter a fully conducting state. The conduction of Q2 will cause the charge on capacitor C8 supplied by R11 and R12 to decrease rapidly and eventually stop. Pin 4 of U1 will remain above -0.158V, and the circuit will eventually reach a stable conducting state, thus continuously supplying power to the downstream protected circuit. At this time, the fuse is in normal working condition.
[0036] When the negative (positive) power path is in an abnormal operating state, the current of the protected circuit flows through sampling resistors R3, R4, and R5 and Q2. The parallel resistors R3, R4, and R5 are connected in series with the equivalent internal resistance of Q2 to form the total sampling resistor. The current flowing through this equivalent resistor will generate a voltage across it. This voltage will charge C7 through R12, and the voltage across C7 will then charge C8 through R11. Normally, the high voltage of C8 is higher than -0.158V. When an overcurrent fault occurs in the protected circuit, the voltage generated across the sampling resistor to charge C8 is lower than -0.158V. This voltage is supplied to pin 4 of U1 through R7. Because this voltage is lower than the threshold voltage of pin 3 of U1 (-0.158V), the voltage output from U1 to pin 1 will increase. This increase in the voltage at pin 1 of U1 will pull up the threshold voltage through resistor R18, forming the first positive feedback. The increased threshold voltage widens the voltage difference between pins 3 and 4 of U1, making pin 3 higher than pin 4, thus causing pin 1 of U1 to quickly rise. Since the voltage at pin 1 of U1 is the control voltage for Q2, the increase in the control voltage increases the internal equivalent resistance of Q2, thereby increasing the total sampling resistance. Because of the increased equivalent resistance, the voltage across this resistor also increases. This gradually increasing voltage charges C7 and C8 through R12 and R11, causing the voltage at C8 to gradually decrease, forming a second positive feedback loop. Through the combined effects of the first and second positive feedback loops, two positive feedback circuits are formed, causing the entire circuit to quickly enter an avalanche reversal state, resulting in a rapid increase in the output voltage of U1 and a rapid turn-off of Q2. R12 and R11 then charge and reduce the voltage at C8, which is then led to pin 4 of U1 through R7, locking the output pin 1 of U1 at a high level. This locks the fuse, putting it in the open state. The power supply to the protected circuit will be disconnected, and the circuit will be in an abnormal working state. When the negative (positive) power path is in the recovery state, disconnecting the power supply input and troubleshooting the protected circuit before powering on again will reset the circuit according to the normal operating procedure of the positive power path. If the protected circuit fault persists, the electronic fuse will repeat the process of the abnormal operating state of the positive power path, disconnecting the circuit for protection.
[0037] It should be noted that the severity of the overcurrent determines the tripping speed of the electronic fuse, which can trip in as little as 0.001 seconds. The maximum tripping speed is clamped by the voltage of LED1 for more than 0.0005 seconds to protect against instantaneous peak currents of capacitive or inductive loads. LED1 illuminates when the circuit is in protection mode, serving as an indicator.
[0038] Functionality can be expanded by reserving a control reset switch interface. Driven by additional circuitry, it can perform the following functions: 1. In case of a fault, it can attempt to reset the electronic fuse without shutting off the main power. 2. In conjunction with the control circuit, the electronic fuse can be used as a power switch.
[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. An electronic fuse circuit connected in series in the power supply path, characterized in that, include: The circuit includes a regulated power supply circuit, a threshold reference circuit, a power switch and current sampling circuit, a shaping and filtering circuit, a power-on reset circuit, a comparison control circuit, a dual positive feedback circuit, and a reserved control reset interface. The power switch and current sampling circuit connects the power transistor and a sampling resistor in series in the main power path; the sampling voltage includes the common voltage drop across the sampling resistor and the equivalent internal resistance of the power transistor. The comparison control circuit compares the sampling voltage with the set voltage of the threshold reference circuit and outputs a control level to drive the power transistor to turn on or off. The dual positive feedback circuit forms a two-stage linked avalanche reversal when overcurrent is triggered, causing the power transistor to quickly lock off. The power-on reset circuit initializes the circuit to a shutdown state upon power-on, and enters normal conduction after a soft start. The reserved control reset interface is used for external reset or as a power switch control.
2. The electronic fuse circuit according to claim 1, characterized in that, When the power path is a negative path, the power transistor is an N-MOS transistor; wherein, when the circuit is working normally, the power transistor remains on, and when there is an overcurrent, the sampling voltage rises, the comparator control circuit flips and quickly turns off the N-MOS transistor and latches it through double positive feedback.
3. The electronic fuse circuit according to claim 1, characterized in that, When the power path is a positive path, the power transistor is a P-MOS transistor; when the circuit is working normally, the power transistor remains on; when there is an overcurrent, the sampling voltage changes in the reverse direction, the comparison control circuit flips and quickly turns off the P-MOS transistor and latches it through double positive feedback.
4. The electronic fuse circuit according to claim 1, characterized in that, The dual positive feedback circuit includes: First positive feedback: Changes in the comparator output pull down / up the threshold voltage, accelerating the comparator switching; Second positive feedback: The power transistor is turned off, which increases its equivalent internal resistance, further increasing the sampling voltage and continuously driving the latch-off. Two positive feedback loops work together to achieve avalanche-style rapid shutdown, with the fastest shutdown time being ≤0.001s.
5. The electronic fuse circuit according to claim 1, characterized in that, The power-on reset circuit is configured such that: at the moment of power-on, a capacitor provides an instantaneous reset level, causing the power transistor to be initially turned off; after the capacitor is fully charged, it automatically releases the reset, and the circuit enters the normal operating range, avoiding false protection due to power-on surge.
6. The electronic fuse circuit according to claim 1, characterized in that, It also includes a fault indication circuit: the fault indication circuit consists of an LED and a current limiting element; wherein, the fault indication circuit lights up when the protection is activated, and the fault indication circuit is used to indicate the overcurrent fault status.
7. The electronic fuse circuit according to claim 1, characterized in that, The sampling resistor is composed of multiple resistors connected in parallel, and the protection current threshold can be adjusted by configuring the resistance value; the threshold reference circuit outputs a stable reference voltage to achieve high-precision overcurrent detection.
8. The electronic fuse circuit according to claim 1, characterized in that, The reserved control reset interface supports external signal reset, which can release the latch without power failure; or, in conjunction with external control, the electronic fuse can be used as a controllable power switch.
9. A method for protecting electronic fuses, characterized in that, It includes the following steps: S1: Power-on reset, the circuit is initially shut down, and after soft start, the power transistor is turned on to enter normal power supply; S2: Real-time acquisition of the total voltage drop between the sampling resistor connected in series in the power path and the equivalent internal resistance of the power transistor; S3: Compare the collected voltage with the set threshold, and keep it conducting under normal conditions; S4: Triggers double positive feedback during overcurrent, causing the comparator to avalanche flip, quickly turning off the power transistor and latching the protection state; S5: After troubleshooting, power on again or reset via external interface to restore normal operation.
10. The electronic fuse protection method according to claim 9, characterized in that, The degree of overcurrent determines the turn-off speed. The circuit sets the minimum blanking time through LED clamping, which is compatible with the peak starting current of capacitive and inductive loads and avoids malfunctions.