Semiconductor Fuse: Symbol, HSN code, Selection, & Advantages

A semiconductor fuse, also known as a semiconductor protection fuse or an SMD fuse, is a type of electrical fuse that is specifically designed to protect semiconductor devices, such as diodes, transistors, and integrated circuits, from overcurrent and overvoltage conditions. These fuses are typically made of a small piece of semiconductor material, such as silicon, that is placed in the circuit in series with the protected device.

What is Semiconductor Fuse?

These fuses are typically made of a small piece of semiconductor material, such as silicon, that is placed in the circuit in series with the protected device. When an overcurrent or overvoltage condition occurs, the fuse element heats up and begins to melt, breaking the circuit and protecting the semiconductor device from damage. Semiconductor fuses are commonly used in a wide range of electronic devices and systems, including power supplies, computers, telecommunications equipment, and consumer electronics.

Semiconductor fuse symbol

The symbol for a semiconductor fuse in a circuit diagram is typically a diagonal line with a small circle on one end. This symbol represents the fuse element of the semiconductor fuse, which is designed to melt or break when an overcurrent or overvoltage condition occurs, interrupting the flow of current and protecting the semiconductor device or other electronic equipment. The symbol can be found in different ways, it can be represented by a rectangular box with two diagonal lines crossing each other.

It’s important to note that different manufacturers and organizations may use slightly different symbols for semiconductor fuses, and it’s always best to consult the manufacturer’s documentation or a professional electrician to ensure the correct interpretation of the symbols used in a particular circuit diagram.

What is the HSN Code of Semiconductor Fuse?

The HSN (Harmonized System of Nomenclature) code is a system used to classify goods for the purpose of taxation.

The HSN code for Semiconductor Fuse is 8536.

The code 8536 covers “Electrical Apparatus for switching or protecting electrical circuits, or for making connections to or in electrical circuits (for example, switches, relays, fuses, surge suppressors, plugs, sockets, lamp-holders, and other connectors, junction boxes), for a voltage not exceeding 1000 volts.”

This means that Semiconductor Fuses fall under the category of electrical apparatus for switching or protecting electrical circuits and are assigned the HSN code 8536.

It’s important to note that the HSN codes are subject to change and it’s best to check with the relevant authorities for the most up-to-date code.

Semiconductor Fuse Characteristics

Semiconductor fuses are characterized by their time-current characteristics, which is a graph that shows how the current flowing through the fuse changes over time in response to an overcurrent or overvoltage condition. The time-current characteristic of a semiconductor fuse can be divided into two regions: the operating region and the melting region.

1. Operating Region: In the operating region, the current flowing through the fuse is below the fuse’s current rating. In this region, the fuse does not melt and the circuit remains intact.
2. Melting Region: In the melting region, the current flowing through the fuse exceeds the fuse’s current rating. In this region, the fuse begins to heat up and melt, breaking the circuit and protecting the semiconductor device or other electronic equipment from damage.

The time-current characteristic of a semiconductor fuse can also be described by its time-lag and current-limiting characteristics.

1. Time-lag characteristics: Time-lag characteristics refer to the time it takes for the fuse to melt when an overcurrent condition occurs. Fuses with a fast-acting time-lag characteristic will melt quickly, providing protection for the semiconductor device or other electronic equipment in the event of a high inrush current or transient overcurrent condition.
2. Current-limiting characteristics: Current-limiting characteristics refer to the ability of a fuse to limit the current flowing through the circuit after an overcurrent condition occurs. Fuses with a high current-limiting characteristic will limit the current flowing through the circuit, providing protection for the semiconductor device or other electronic equipment in the event of a steady state under overcurrent conditions.

In summary, the time-current characteristic of a semiconductor fuse is a graph that shows how the current flowing through the fuse changes over time in response to an overcurrent or overvoltage condition. It’s important to match the time-current characteristic of the fuse to the expected overcurrent and overvoltage conditions of the circuit to ensure adequate protection. The time-current characteristic can be divided into the operating region and the melting region, and it can also be described by its time-lag and current-limiting characteristics.

It’s important to consult the manufacturer’s datasheet to understand the time-current characteristic of a specific semiconductor fuse, as well as consult with experts to ensure that the selected fuse has the appropriate time-current characteristics for the specific application.

It’s also important to note that the current vs time graph is one of the important parameters to be considered while selecting a semiconductor fuse, but it’s not the only factor, as mentioned earlier factors such as current rating, voltage rating, environmental conditions, size and package, and cost also play a significant role in the selection of the semiconductor fuse.

Construction of Semiconductor Fuse

The construction of a semiconductor fuse is relatively simple. It typically consists of the following components:

1. Fuse Element: This is the core component of the semiconductor fuse and is typically made of a small piece of semiconductor material, such as silicon. The fuse element is designed to melt when an overcurrent or overvoltage condition occurs, breaking the circuit and protecting the semiconductor device from damage.
2. Encapsulation: The fuse element is encased in a small plastic or ceramic package that serves to protect it from the environment and mechanical damage. The package is usually designed to be surface-mountable so that it can be easily soldered onto a circuit board.
3. Leads: The encapsulation package has leads that are used to connect the semiconductor fuse to the circuit. These leads are typically made of a conductive material such as copper, and they are connected to the fuse element inside the package.
4. Marking: Some semiconductor fuses have markings on them indicating their electrical ratings and other specifications. These markings are usually printed on the surface of the encapsulation package.

Overall, Semiconductor fuses are designed to be small and compact, with a simple construction that makes them easy to integrate into a circuit board. They can also be designed to be surface-mountable, which makes them easy to install and replace. They are designed to protect electronic devices and systems from damage caused by overcurrent and overvoltage conditions.

Difference between Semiconductor Fuse and HRC Fuse

Semiconductor fuses and HRC (High Rupturing Capacity) fuses are both types of electrical fuses that are used to protect electronic devices and systems from overcurrent and overvoltage conditions. However, there are some key differences between the two types of fuses.

Semiconductor Fuse	HRC Fuse
A Semiconductor Fuse is a small piece of Semiconductor material encased in a small plastic or ceramic package.	An HRC Fuse is a Metal alloy encased in a glass or ceramic tube.
Low current rating	High current rating
Low voltage rating	High voltage rating
Low Rupture Capacity	High Rupture capacity
Applications: Power supplies, computers, telecommunications equipment, and electronics	Applications: Power distribution systems, motor control centers, and electrical panels
Low space requirement	High Space requirement
Less Expensive	More Expensive

Semiconductor Fuse Selection

Selecting the right semiconductor fuse for a particular application is important to ensure that the protected device is adequately protected from overcurrent and overvoltage conditions, while also being cost-effective. Here are some factors to consider when selecting a semiconductor fuse:

1. Current Rating: The current rating of the fuse should be matched to the expected current level of the circuit. It’s important to select a fuse with a rating that is slightly higher than the expected current level to ensure adequate protection.
2. Voltage Rating: The voltage rating of the fuse should be matched to the expected voltage level of the circuit. It’s important to select a fuse with a voltage rating that is higher than the expected voltage level to ensure adequate protection.
3. Time-current Characteristics: The time-current characteristics of the fuse should be matched to the expected overcurrent and overvoltage conditions of the circuit. Fuses with a fast-acting time-current characteristic are best suited for circuits with high inrush current or transient overcurrent conditions, while fuses with a slow-acting time-current characteristic are best suited for circuits with steady-state overcurrent conditions.
4. Environmental conditions: The environmental conditions where the fuse will be used should be considered. For example, if the fuse will be used in a harsh environment, such as high temperature or vibration, a fuse with high resistance to these conditions should be selected.
5. Size and package: The size and package of the fuse should be considered when selecting a semiconductor fuse. Semiconductor fuses are designed to be small and compact, and they can be surface-mountable, which makes them easy to integrate into a circuit board.
6. Cost: The cost of the fuse should also be considered when selecting a semiconductor fuse. It’s important to select a fuse that offers the required level of protection at a cost-effective price.

In conclusion, when selecting a semiconductor fuse it’s important to consider the current rating, voltage rating, time-current characteristics, environmental conditions, size and package, and cost of the fuse. By considering all these factors, the appropriate semiconductor fuse can be selected to ensure adequate protection for the circuit and equipment, while also being cost-effective.

Examples of semiconductor fuse selections

1. Low voltage power supply: In a low voltage power supply, the expected current level is relatively low, and the expected voltage level is also low. For this application, a small surface-mountable semiconductor fuse with a current rating of 250mA and a voltage rating of 60V would be a suitable selection.
2. Automotive electronic control unit: In an automotive electronic control unit, the expected current level can be high, and the expected voltage level is also high. For this application, a semiconductor fuse with a current rating of 10A and a voltage rating of 48V would be a suitable selection. Additionally, the fuse should be designed to withstand the environmental conditions of the automotive industry, such as vibration and high temperatures.
3. Telecom power supply: In a telecom power supply, the expected current level can be high, and the expected voltage level is also high. For this application, a semiconductor fuse with a current rating of 15A and a voltage rating of 125V would be a suitable selection. Additionally, the fuse should be designed to withstand the environmental conditions of the telecommunications industry, such as high humidity and temperature fluctuations.
4. Industrial control system: In an industrial control system, the expected current level can be high, and the expected voltage level is also high. For this application, a semiconductor fuse with a current rating of 20A and a voltage rating of 240V would be a suitable selection. Additionally, the fuse should be designed to withstand the environmental conditions of the industrial sector, such as vibration and high temperatures.

It’s important to note that these are just examples and the specific requirements for each application will vary depending on the system and the devices that need to be protected. It’s always recommended to consult the manufacturer’s datasheet and consult with experts to select the best-suited fuse for the specific application.

How to check Semiconductor Fuse?

Here are a few common methods for checking the functionality of a semiconductor fuse:

1. Continuity test: This method involves using a continuity tester or multimeter to check for continuity through the fuse. The continuity tester or multimeter should indicate a closed circuit if the fuse is functioning properly.
2. Visual inspection: This method involves physically inspecting the fuse for any signs of damage or wear, such as a melted or broken fuse element, discoloration, or deformation.
3. Resistance test: This method involves using a multimeter to measure the resistance of the fuse. A functioning fuse should have a very low resistance, typically less than an ohm.
4. Current test: This method involves measuring the current flowing through the fuse with a clamp meter or other current-measuring device. A functioning fuse should have a current within its specified rating.

It’s important to note that these methods are not mutually exclusive and can be used in combination to check the functionality of a semiconductor fuse. It’s also important to note that before performing any tests, the power to the circuit should be turned off to avoid any electrical hazards.

Semiconductor Fuse Advantages

Semiconductor fuses offer several advantages over other types of fuses and protection devices, including:

1. Small size: Semiconductor fuses are typically small in size, which makes them easy to integrate into circuit boards and other electronic equipment.
2. Fast-acting: Semiconductor fuses are typically fast-acting, which means that they can respond quickly to overcurrent and overvoltage conditions, providing protection for the semiconductor device or other electronic equipment.
3. High thermal stability: Semiconductor fuses are designed to have high thermal stability, which means that they can withstand high temperatures without being damaged.
4. Low voltage drop: Semiconductor fuses have low voltage drops, which means that they do not significantly affect the voltage level in the circuit and minimize energy loss.
5. Cost-effective: Semiconductor fuses are relatively less expensive than other types of fuses, making them a cost-effective solution for protecting semiconductor devices and other electronic equipment.
6. High resistance to vibration: Semiconductor fuses are designed to have high resistance to vibration, which means that they can withstand the mechanical stresses caused by vibration without being damaged.
7. Surface mountable: Semiconductor fuses are typically designed to be surface-mountable, which makes them easy to install and replace.
8. High current interruption: Semiconductor fuses can safely interrupt high levels of current to protect the equipment.
9. Variety of sizes and ratings: They are available in a wide range of current and voltage ratings to suit different applications.

In conclusion, semiconductor fuses offer several advantages over other types of fuses and protection devices, such as small size, fast-acting, high thermal stability, low voltage drop, cost-effective, high resistance to vibration, surface mountable, high current interruption, and variety of sizes and ratings.

Semiconductor Fuse Applications

Semiconductor fuses are widely used in a variety of electronic applications due to their small size, fast-acting time-current characteristics, and high thermal stability. Some common applications of semiconductor fuses include:

1. Power supplies: Semiconductor fuses are used to protect power supplies, such as those used in computers, telecommunications equipment, and consumer electronics, from overcurrent and overvoltage conditions.
2. Motor control centers: They are also used in motor control centers to protect motors and other equipment from overcurrent conditions.
3. Uninterruptible power supplies (UPS): Semiconductor fuses are used in uninterruptible power supplies (UPS) to protect the UPS and the equipment connected to it from overcurrent conditions.
4. Solar power systems: They are also used in solar power systems to protect solar panels and other equipment from overcurrent conditions.
5. Surface mountable: Semiconductor fuses are used in automotive electronic systems, such as electronic control units (ECUs) and engine management systems, to protect electronic devices from overcurrent conditions.
6. Medical equipment: They are also used in medical equipment to protect electronic devices from overcurrent conditions.
7. Industrial equipment: Semiconductor fuses are used in industrial equipment, such as process control systems and industrial automation systems, to protect electronic devices from overcurrent conditions.

In summary, Semiconductor fuses are widely used in a variety of electronic applications due to their small size, fast-acting time-current characteristics, and high thermal stability. They are commonly used in power supplies, motor control centers, uninterruptible power supplies, solar power systems, automotive electronic systems, medical equipment, and industrial equipment.