Resettable large-current three-terminal direct-current rapid electronic fuse

Abstract

The invention relates to the technical field of fuses, in particular to a resettable large-current three-terminal direct-current rapid electronic fuse which comprises a current sampling module, a signal amplification module, an overcurrent judgment module, a threshold setting module, a state latch module, a state reset module, a drive circuit module and an MOS switch U5. The current sampling module detects the current during the operation of the electronic fuse, the signal amplification module isolates and amplifies the collected current signal, the overcurrent discrimination module compares the isolated and amplified current signal with a preset overcurrent threshold value, and if the current does not exceed the threshold value, the electronic fuse continues to work normally. And if the current exceeds the preset threshold, the overcurrent judgment module outputs an overcurrent state signal, and the signal enables the driving circuit module to control the MOS switch U5 to perform a turn-off action, so that the purpose of protection is achieved. With the adoption of the structure, the electronic fuse is adopted, so that compared with the traditional fuse, the electronic fuse is higher in response speed and does not need to be replaced.

Description

Technical Field

[0001] The invention relates to the technical field of fuses, and in particular to a resettable high-current three-terminal direct current fast electronic fuse. Background Art

[0002] Fuses are very common in electrical appliances. They are devices that protect circuits by opening a circuit. When an overload or short circuit occurs in a circuit, the conductor inside a traditional fuse will heat up due to the overload, eventually causing the conductor to melt, cutting off the circuit and protecting the circuit and equipment.

[0003] The development of fuse technology has been very mature, but with the continuous development of electronic equipment, new protection devices are also emerging, such as overspeed protectors, overvoltage protectors, etc. These devices can protect the circuit more accurately and improve the reliability and safety of the equipment. Fuses can be classified according to different classification standards. The following are some common classification methods; classification according to working principle: thermal fuse, thermal fuse, electronic fuse and gas fuse, etc., classification according to appearance: glass tube fuse, ceramic fuse, plastic fuse, etc., classification according to rated current: 1A, 2A, 3A, etc. Classification according to rated voltage: 125V, 250V, 600V, etc., classification according to fast disconnection and slow disconnection: fast disconnection fuse and slow disconnection fuse, classification according to application scenarios: automotive fuse, household appliance fuse, electronic product fuse, etc., classification according to insurance mechanism: fusible fuse, self-resetting fuse, resettable fuse.

[0004] However, the circuits of existing electronic fuses are complex, and require external circuits to set the working state, and the response speed is not fast enough. Summary of the invention

[0005] The purpose of the present invention is to provide a resettable high-current three-terminal DC fast electronic fuse to solve the problems of the electronic fuse in the prior art that the circuit is complex, an external circuit is required to set the working state, and the response speed is not fast enough.

[0006] To achieve the above-mentioned object, the present invention provides a resettable high-current three-terminal DC fast electronic fuse, which comprises a current sampling module, a signal amplification module, an overcurrent determination module, a threshold setting module, a state latch module, a state reset module, a drive circuit module and a MOS switch U5, wherein the current sampling module is respectively connected to the signal amplification module and the MOS switch, the overcurrent determination module is respectively connected to the signal amplification module and the threshold setting module, the state latch module is respectively connected to the overcurrent determination module and the state reset module, and the drive circuit module is respectively connected to the state latch module and the MOS switch;

[0007] The current sampling module is used to monitor the current in the circuit in real time;

[0008] The signal amplification module is used to isolate and amplify the collected current signal;

[0009] The threshold setting module is used to set the overcurrent threshold value;

[0010] The overcurrent determination module is used to compare the isolated and amplified current signal with a preset overcurrent threshold value;

[0011] The state latch module is used to save the working state of the driving circuit module;

[0012] The state reset module is used to perform a reset operation to reinitialize the state latch module of the electronic fuse;

[0013] The driving circuit module is used to control and drive the MOS switch.

[0014] The resettable high-current three-terminal DC fast electronic fuse further comprises a power supply module, which is used to supply power to the overcurrent determination module, the threshold setting module, the state latch module, the state reset module and the drive circuit module.

[0015] Among them, a current detection chip U1 is arranged between the current acquisition module and the signal amplification module, a sampling resistor R1 is arranged on the current acquisition module, pin 1 of the current detection chip U1 and pin 8 of the current detection chip U1 are both connected to the sampling resistor R1, a potentiometer RP1 is arranged on the signal amplification module, pin 4 of the current detection chip U1 is grounded, and pin 5 of the current detection chip U1 is connected to the potentiometer RP1.

[0016] Among them, the threshold setting module includes a resistor R3 and a resistor R4, and the resistor R3 and the resistor R4 are both connected to the power supply module. The overcurrent judgment module is provided with a dual operational amplifier U2, and the negative end of the first-stage operational amplifier in the dual operational amplifier U2 is connected to the resistor R3 and the resistor R4, and the positive end of the first-stage operational amplifier in the dual operational amplifier U2 is connected to the potentiometer RP1.

[0017] Among them, a D trigger U3 is provided on the state latch module, pin 1 of the D trigger U3 is connected to the capacitor C3, pin 3 of the D trigger U3 is connected to the output end of the second operational amplifier in the dual operational amplifier U2, a resistor R5 is provided between pin 1 of the D trigger U3 and pin 4 of the D trigger U3, and a capacitor C4 is provided on the state reset module, and the capacitor C4 is connected to pin 6 of the D trigger U3 and pin 4 of the D trigger U3.

[0018] Among them, the driving circuit module is provided with an optocoupler U4, a resistor R7 and a resistor R9, the power supply module is provided with an isolated DCDC module U7, the pin 1 of the optocoupler U4 is connected to the pin 6 of the D trigger U3, the resistor R7 is provided between the pin 2 of the optocoupler U4 and the capacitor C4, the pin 3 of the optocoupler U4 is connected to the MOS switch U5 and the pin 3 of the isolated DCDC module U7, and the resistor R9 is provided between the pin 3 of the optocoupler U4 and the pin 3 of the isolated DCDC module U7.

[0019] Wherein, the power module is also connected to a light emitting diode D2 and a light emitting diode D3.

[0020] A resettable high-current three-terminal DC fast electronic fuse of the present invention detects the current in operation of the electronic fuse through a current sampling module, isolates and amplifies the current signal collected by the signal amplification module, and uses the overcurrent discrimination module to compare the isolated and amplified current signal with a preset overcurrent threshold value. If the current does not exceed the threshold, the normal operation continues. If it exceeds the preset threshold, the overcurrent discrimination module will output an overcurrent state signal, which will cause the drive circuit module to control the MOS switch U5 to perform a shutdown action. At this time, there will be no current supply to the load, thereby achieving protection. Purpose, adopting the above structure, since the fuse adopts electronic insurance, the response speed is faster than the response time of several seconds or hundreds of milliseconds of the traditional fuse, and when the MOS switch U5 is turned off, the overcurrent judgment module recognizes that the circuit is not overcurrent, but through the setting of the state latch module, this state will be maintained until the next reset, so the drive circuit module will not have any other action, and the MOS switch U5 will remain in the off state. When the device is powered off, the fault is solved, and the power is turned on again, under the action of the state reset module, the state latch module is reset, and the whole circuit starts working again. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The present invention provides a circuit diagram of a resettable high-current three-terminal DC fast electronic fuse. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0024] See also Figure 1 The present invention provides a resettable high-current three-terminal DC fast electronic fuse, which comprises a current sampling module, a signal amplification module, an overcurrent determination module, a threshold setting module, a state latch module, a state reset module, a drive circuit module and a MOS switch U5, wherein the current sampling module is respectively connected to the signal amplification module and the MOS switch, the overcurrent determination module is respectively connected to the signal amplification module and the threshold setting module, the state latch module is respectively connected to the overcurrent determination module and the state reset module, and the drive circuit module is respectively connected to the state latch module and the MOS switch;

[0025] The current sampling module is used to monitor the current in the circuit in real time;

[0026] The signal amplification module is used to isolate and amplify the collected current signal;

[0027] The threshold setting module is used to set the overcurrent threshold value;

[0028] The overcurrent determination module is used to compare the isolated and amplified current signal with a preset overcurrent threshold value;

[0029] The state latch module is used to store the driving circuit module;

[0030] The state reset module is used to perform a reset operation to reinitialize the state latch module of the electronic fuse;

[0031] The driving circuit module is used to control and drive the MOS switch.

[0032] In this embodiment, the current sampling module detects the current in the operation of the electronic fuse, the current signal collected by the signal amplification module is isolated and amplified, and the overcurrent judgment module is used to compare the isolated and amplified current signal with the preset overcurrent threshold value. If the current does not exceed the threshold, it continues to work normally. If it exceeds the preset threshold, the overcurrent judgment module will output an overcurrent state signal, which will cause the drive circuit module to control the MOS switch U5 to perform a shutdown action. At this time, there will be no current supply to the load, thereby achieving the purpose of protection. With the above structure, since the fuse adopts an electronic fuse, the response speed is faster than the response time of several seconds or hundreds of milliseconds of the traditional fuse, and when the MOS switch U5 is turned off, the overcurrent judgment module recognizes that the circuit does not overcurrent, but through the setting of the state latch module, this state will be maintained until the next reset, so the drive circuit module will not have any other action, and the MOS switch U5 will remain in the off state. When the device is powered off, the fault is solved, and the power is turned on again, under the action of the state reset module, the state latch module is reset, and the entire circuit starts working again.

[0033] Furthermore, the resettable high-current three-terminal DC fast electronic fuse also includes a power supply module, which is used to supply power to the overcurrent determination module, the threshold setting module, the state latch module, the state reset module and the drive module.

[0034] In this implementation, the overcurrent determination module, the threshold setting module, the state latch module, and the state reset module are powered by the power supply module.

[0035] Furthermore, a current detection chip U1 is arranged between the current acquisition module and the signal amplification module, a sampling resistor R1 is arranged on the current acquisition module, pin 1 of the current detection chip U1 and pin 8 of the current detection chip U1 are both connected to the sampling resistor R1, a potentiometer RP1 is arranged on the signal amplification module, pin 4 of the current detection chip U1 is grounded, pin 5 of the current detection chip U1 is connected to the potentiometer RP1, the threshold setting module includes a resistor R3 and a resistor R4, the resistor R3 and the resistor R4 are both connected to the power supply module, a dual operational amplifier U2 is arranged on the overcurrent discrimination module, the negative end of the first-stage operational amplifier in the dual operational amplifier U2 is connected to the resistor R3 and the resistor R4, and the positive end of the first-stage operational amplifier in the dual operational amplifier U2 is connected to the potentiometer RP1.

[0036] In this embodiment, during the current input process, power is supplied to the load through the sampling resistor R1 and the MOS switch U5, and the current detection chip U1 is used to amplify the tiny voltage across the sampling resistor R1, thereby isolating and amplifying the collected current signal. The first-stage operational amplifier in the dual operational amplifier U2 is used as a voltage comparator, and the reference voltage of the first-stage operational amplifier in the dual operational amplifier U2 is obtained by dividing the output voltage of the power module through the resistors R3 and R4, and is transmitted to the negative end of the first-stage operational amplifier in the dual operational amplifier U2. The positive end of the first-stage operational amplifier in the dual operational amplifier U2 obtains the current detection voltage after isolation and amplification through the potentiometer RP1. By adjusting the potentiometer RP1, different overcurrent protection thresholds can be set. When the positive terminal voltage of the first-stage operational amplifier in the dual operational amplifier U2 exceeds the negative terminal voltage, a high level will be output, and since the load capacity of the first-stage operational amplifier in the dual operational amplifier U2 is limited, the second-stage operational amplifier in the dual operational amplifier U2 is used as a voltage follower to increase the load capacity.

[0037] Furthermore, a D flip-flop U3 is provided on the state latch module, pin 1 of the D flip-flop U3 is connected to a capacitor C3, pin 3 of the D flip-flop U3 is connected to the output end of the second operational amplifier in the dual operational amplifier U2, a resistor R5 is provided between pin 1 of the D flip-flop U3 and pin 4 of the D flip-flop U3, and a capacitor C4 is provided on the state reset module, and the capacitor C4 is connected to pin 6 of the D flip-flop U3 and pin 4 of the D flip-flop U3 and grounded.

[0038] In this embodiment, the D flip-flop U3 is used for state locking, and the value table of the D flip-flop U3 is as follows:

[0039]

[0040] During circuit operation, when the second-stage operational amplifier in the dual operational amplifier U2 outputs a high level to pin 3 of the D trigger U3, a rising edge signal is provided to pin 1 of the D trigger U3 through the capacitor C3. It can be seen from the above table that pin 6 of the D trigger U3 will have a high level output. Due to the presence of the resistor R5, the voltage on the capacitor C3 will gradually discharge to a low level to wait for the next trigger. When the D trigger U3 is powered on, since the voltage across the capacitor C4 cannot change suddenly, pin 7 of the D trigger U3 is a low level, the D trigger U3 is reset, and outputs a low level. As the capacitor C4 is charged, the voltage of pin 7 of the D trigger U3 gradually reaches a high level, so that the D trigger U3 can wait for triggering.

[0041] Furthermore, the driving circuit module is provided with an optocoupler U4, a resistor R7 and a resistor R9, the power supply module is provided with an isolated DCDC module U7, pin 1 of the optocoupler U4 is connected to pin 6 of the D trigger U3, the resistor R7 is provided between pin 2 of the optocoupler U4 and the capacitor C4, the pin 3 of the optocoupler U4 is connected to the MOS switch U5 and pin 3 of the isolated DCDC module U7, and the resistor R9 is provided between pin 3 of the optocoupler U4 and pin 3 of the isolated DCDC module U7.

[0042] In this embodiment, since the MOS switch U5 is used as a high-side application, signal isolation is performed through the optocoupler U4, and power is supplied through the isolated DCDC module U7. When the pin 6 of the D flip-flop U3 outputs a low level, the optocoupler U4 is blocked, the voltages at both ends of the resistor R9 are the same, the voltage of the isolated DCDC module U7 is applied to the gate-source of the MOS switch U5, VGS>Vth, and the MOS switch U5 is turned on. When the pin 6 of the D flip-flop U3 outputs a high level, the optocoupler U4 is turned on, VGS is close to 0V, and the MOS switch U5 is turned off, cutting off the power supply circuit to the load.

[0043] Furthermore, the power module is also connected to a light emitting diode D2 and a light emitting diode D3.

[0044] In this embodiment, the light-emitting diode D2 and the light-emitting diode D3 respectively indicate the power supply status and the working status of the MOS switch U5. When the light-emitting diode D2 is lit, it indicates that the isolated power supply is normal, and indirectly indicates that the front-stage +5V power supply is also normal. When the light-emitting diode D3 is lit, it indicates that the MOS switch U5 is turned on and supplies power to the load normally. When the light-emitting diode D3 is off, it indicates that the MOS switch U5 is turned off, the circuit is in a protection state, and the load current is zero.

[0045] The beneficial effects of the present invention are as follows: the overcurrent protection achieved by the electronic fuse by shutting off the current path is different from the protection mechanism achieved by the traditional fuse by fusing, there is no substantial device damage, and it can work again through the reset process of power off and power on again, without the need to replace any materials. It is also different from the principle of the PTC self-resettable fuse. The recovery of the PTC self-resettable fuse takes time, so that its temperature drops to a certain level before it can work again, while the reset speed of the electronic fuse is very fast, and manual operation only takes a few seconds. In addition, due to the protection mechanism and volume limitations, the PTC self-resettable fuse cannot be made too large. The maximum current specification commonly used in the market is about 5A, which is not enough for use in many occasions. The electronic fuse obtains the current value through current sampling or current mirroring. Different sampling coefficients and switch tubes of different power levels can be configured according to different application scenarios, so it can be used in many high-current environments, such as radar, transmitter power amplifier, automotive electrical appliances, etc. At the same time, in order to facilitate installation and use, this electronic fuse has a three-port structure, namely input, output and grounding. Unlike traditional fuses that only have input and output terminals, electronic fuses require a certain amount of internal power to work, so they need a grounding port. In addition, electronic fuses have a certain power consumption, and large-area grounding is also conducive to the heat dissipation of this product itself. Installing the grounding terminal on a radiator or chassis can also facilitate installation and use. In summary, since this electronic fuse is an electronic fuse with a full hardware architecture, its response speed is very fast, usually in microseconds. In special scenarios, it can even achieve nanosecond response. Compared with the response time of traditional fuses of several seconds or hundreds of milliseconds, the speed is increased by several orders of magnitude, which can greatly improve the safety of sensitive and valuable devices and avoid major property losses.

[0046] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A resettable high current three-terminal DC fast electronic fuse, characterized in that: It includes a current sampling module, a signal amplification module, an overcurrent determination module, a threshold setting module, a state latch module, a state reset module, a drive circuit module and a MOS switch U5, wherein the current sampling module is connected to the signal amplification module and the MOS switch respectively, the overcurrent determination module is connected to the signal amplification module and the threshold setting module respectively, the state latch module is connected to the overcurrent determination module and the state reset module respectively, and the drive circuit module is connected to the state latch module and the MOS switch respectively; The current sampling module is used to monitor the current in the circuit in real time; The signal amplification module is used to isolate and amplify the collected current signal; The threshold setting module is used to set the overcurrent threshold value; The overcurrent determination module is used to compare the isolated and amplified current signal with a preset overcurrent threshold value; The state latch module is used to store the output state of the driving circuit module; The state reset module is used to perform a reset operation to reinitialize the state latch module of the electronic fuse; The driving circuit module is used to control and drive the MOS switch.

2. The resettable high current three-terminal DC fast electronic fuse according to claim 1, characterized in that: The resettable high-current three-terminal DC fast electronic fuse also includes a power supply module, which is used to supply power to the overcurrent determination module, the threshold setting module, the state latch module, the state reset module and the MOS switch.

3. The resettable high current three-terminal DC fast electronic fuse as claimed in claim 2, characterized in that: A current detection chip U1 is arranged between the current acquisition module and the signal amplification module, a sampling resistor R1 is arranged on the current acquisition module, pin 1 of the current detection chip U1 and pin 8 of the current detection chip U1 are both connected to the two ends of the sampling resistor R1, pin 4 of the current detection chip U1 is grounded, a potentiometer RP1 is arranged on the signal amplification module, pin 5 of the current detection chip U1 is connected to the potentiometer RP1, the other end of RP1 is grounded, and the middle tap is the output signal sent to the overcurrent judgment module.

4. The resettable high current three-terminal DC fast electronic fuse as claimed in claim 3, characterized in that: The threshold setting module includes a resistor R3 and a resistor R4, and the resistor R3 and the resistor R4 are connected to the power module to form a voltage divider circuit, and this intermediate voltage is used as a comparison reference voltage of the operational amplifier U2. The overcurrent discrimination module is provided with a dual operational amplifier U2, and the first stage of the dual operational amplifier U2 is used as a voltage comparator, and the negative end of the operational amplifier is connected to the reference voltage end of the resistor R3 and the resistor R4, and the positive end of the first stage operational amplifier in the dual operational amplifier U2 is connected to the middle tap of the potentiometer RP1 as the input voltage of the comparator. When the input voltage is greater than the reference voltage, the comparator outputs a high level, otherwise it outputs a low level. The second operational amplifier in the dual operational amplifier U2 acts as an emitter follower to increase the load capacity.

5. The resettable high current three-terminal DC fast electronic fuse as claimed in claim 4, characterized in that: The state latch module is provided with a D flip-flop U3, the pin 1 of the D flip-flop U3 is connected to the capacitor C3, the pin 3 of the D flip-flop U3 and the capacitor C3 are connected to the output end of the second operational amplifier in the dual operational amplifier U2, when the emitter follower outputs a high level, since the voltage across the capacitor cannot change suddenly, a high level is generated on the pin 1 of U3. A resistor R5 is provided between the pin 1 of the D flip-flop U3 and the D flip-flop ground, which is used for discharge, so that the pin 1 of U3 is normally kept at a low level. In this way, a pulse is formed, which serves as the D flip-flop clock, and thus a state latch circuit is formed. When the emitter follower outputs a high level, the output Q of the D flip-flop U3 also becomes a high level. After that, even if the emitter follower outputs a low level, since there is no pulse signal on pin 1 of U3, the D flip-flop will maintain its original working state. This is the working principle of the latch. The state reset module is provided with a capacitor C4, which is connected to the pin 6 of the D flip-flop U3 and the ground. When U3 is powered on, the voltage across the capacitor C4 cannot change suddenly, and the pin 6 of U3 maintains a low level for a period of time. As C4 is charged, the voltage of the pin 6 of U3 rises to a high level, thus forming a negative pulse to reset the state latch module.

6. The resettable high current three-terminal DC fast electronic fuse as claimed in claim 5, characterized in that: The drive circuit module is provided with an optocoupler U4, a resistor R7 and a resistor R9, and the power module is provided with an isolated DCDC module U7. Pin 1 of the optocoupler U4 is connected to pin 6 of the D trigger U3, and the resistor R7 is provided between pin 2 of the optocoupler U4 and the capacitor C4. Pin 3 of the optocoupler U4 is connected to the gate of the MOS switch U5 and pin 3 of the isolated DCDC module U7, and the voltage divider resistor R9 is provided between pin 3 of the optocoupler U4 and pin 3 of the isolated DCDC module U7. The drain of the MOS switch U5 is connected to the sampling resistor R1, and the source of U5 is connected to the load. When the optocoupler U4 is turned on, the gate-source voltage U GS is zero, and the MOS switch U5 is turned off. The electronic fuse is in an open circuit state, and the load has no power supply. When the optocoupler U4 is turned off, the gate-source voltage U GS is the output voltage of U7, at which time the MOS switch U5 is turned on. The electronic fuse is in working state, and the current supplied to the load is the same as the current flowing through the sampling resistor.

7. The resettable high current three-terminal DC fast electronic fuse according to claim 6, characterized in that: The power module includes a positive 5V circuit and a subsequent isolated DC-DC circuit. The output of the isolated DC-DC is a set of floating positive 5V voltages, which provide a positive bias voltage for the MOS switch U5 when it is turned on. The power module is also connected to a light emitting diode D2 and a light emitting diode D3. When D2 is on, it indicates that the power module has voltage output, and when D3 is on, it indicates that the electronic fuse is in working state.

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