Use Electronic Fuse To Overcome The Limitations Of Traditional Protection Devices

The most common (and the lowest cost) circuit protection form is ordinary fuse.Such fuses are usually based on metal wires or thin metal bands with low melting point temperature.Bundes are usually used in the power supply line. When the rated current exceeds the rated current, the heat generated in the fuse will make the metal wire/The metal band is fused, so that the circuit is disconnected from the power supply.

This disconnection is often not instantaneous, and the time required for fuse melting is inversely proportional to the size of the fault current.If the current is slightHigher than the fuse rated value, it may continue to pass through for a period of time, which affects the power supply rail, causing circuit failure or damage.

The use of fuse is not convenient; once the fuse is melted, it needs to be replaced (usually the user needs to be replaced).If the user (unintentional or intentional) uses the wrong rated value, it will constitute a fire risk.

For circuit protection, you can also use other devices, such as the temperature coefficient  (PTC) ThermistorEssenceThese are installed in  PCB The device resistance will increase as the temperature rises, thereby restricting the current flow.As long as the current is not large (otherwise  PTC The thermal resistance will become open), and the temperature will decrease as the current decreases and the normal operation will be restored.

Although the fuse is no longer needed,  PTC Thermal resistance is non -linear, and in view of its working principle, it is not applicable to the application of wide temperature range.

Electronic fuse

Electronic fuse (also known as  eFuses, This term is by Ansonami & Nbsp;(onsemi) Created when it was launched for the first time) is a alternative to providing basic circuit protection functions and many additional functions today.Generally, they can provide overcurrent (including short circuit), overvoltage, reverse current and overheating protection.

Although these innovative devices have many applications, they are usually used in the scene where heat insertion is pulled out, or the scene where power failures often occur.In addition, it can also be used for applications that are likely to occur in load failure, or systems that need to limit the surge current.

The combination of enable pins and high -precision current control mechanisms can make the device integrate the function of the load switch and fuse, and become the basic construction module of the load point control system in the modern power distribution architecture.

The main advantage of electronic fuse is flexibility and automatic reset function, without user intervention.As a smart device, these additional features enable the electronic fuse to achieve more functions in the system, not limited to overvoltage/Overcurrent protection (electronic fuses performed well in these areas).

For example, many electronic fuses include  power good（PGOOD) The pin can be used with the system controller to accurately supply the power rail according to the prevailing.Some electronic fuses also include three -state pins, which can be used to ensure that at the same time and turn off multiple power rails.

The electronic fuse can detect the reverse current (the traditional fuse cannot be realized), so it is necessary to  ORing The redundant power application is very useful.In addition, it is also applicable to the case where large -capacity capacitors are required after the system is turned off. It is usually used to limit the surging current at the startup.

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Figure  1: Electronic fuse provides a variety of functions to enhance protection

In many applications, capacitors (or capacity loads) may bring challenges, leading to a large surge current, which may damage the component or  PCB line.Electronic fuses can provide a variety of functions to help designers solve this problem, such as self -recovery or restrictions on surging currents, so that capacitors are charged controlled by controlling control.

As a smart device, electronic fuses can monitor temperature, voltage and current, and pass data to the system controller.This is particularly useful when detecting early warning signals of faults.

Electronic fuse in car applications

As more and more technologies are fused in cars, in order to ensure reliable operation and prevent damage, the demand for circuit protection has also increased.Circuit protection is especially important in cars, because the current capacity of batteries is enough to destroy precision electronic components.

Electronic fuses are usually used in the power lines of subsystems (such as head -up display or information entertainment system) to disconnect and turn off these systems when faulty.

In some systems located outside the vehicle, damage to the external component may cause short circuit and damage the internal circuit.For example, the car information system, its external  LNA And  GPS The antenna is connected by an electronic fuse to protect the internal circuit.

If the vehicle system is divided into different areas, it can be provided with overall protection and subsystem protection in the system in the system.

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Figure  2: Sometimes the Class Latey Funder will be used in the automotive area control application

For example, in the advanced driving assistance system  (ADAS) In the domain controller, the main fuse can be connected between the power supply and the main system, and the secondary fuse can be used to protect the system peripherals, such as an ultrasonic parking auxiliary sensor unit installed outside.

The wiring beam in modern cars is a complex subsystem.Once the vehicle is assembled, the replacement cost of the wire beam is high and it is difficult to operate, so protection is important.The cable beam is connected to many power consumption equipment (fan, window motor, air conditioner, other actuators).Bundes are usually used before these systems to protect the lines from being affected by large currents.

The latest electronic fuse technology example

Ansonme  NIV(S)3071 Is a  60 VDC、65 VTR The electronic fuse integrates four independent channels to a single  5.0 mm x 6.0 mm In the package, each channel can support Gundam  2.5 A Continuous current (total  10 ATo.The  RDSon The value is only  80 mΩ, make sure the energy consumption in the electronic fuse is reduced to a lower level.

All channels have a configurable current limit, other functions include output voltage clamps, digital signs indicating faults, configurable current check time, and fixed  1 ms Soft start.

NIV3071 Can be in  -40oC To  +150oC Jacking temperature  (TJ) Work within the range and provide  2 kV & Nbsp;ESD Protection is very suitable for harsh car applications, including  12 V And  48 V。

NIV(S)4461 It is an electronic fuse that provides overcurrent, underwriting and surging current protection in applications such as industrial automation, telecommunications, computing.This device can support Gundam  360 V Voltage, and Gundam  4.2 A Continuous current.

The significant features of this device include low resistance (typical  RDSon = 39 mΩ) and quick card time.This device also includes a programmable current limit  (21-157A), IOU and adjustable conversion rate control.Users configured functions include locks and self -recovery.

NIV(S)4461 Use  DFNN1024 Packaging, the size is only  3.0 mm x 3.0 mmEssenceIt adopts industry standard pin layout, in line with  UL2367 And  IEC62368 standard.

Summarize

Circuit protection is an important part of modern design that can ensure the reliability of circuits and systems and minimize damage when faulty or accidents.

Although traditional fuse provides a certain degree of protection, modern electronic fuses have higher accuracy, greater flexibility and richer functions, which significantly improves the protection level.