What is an Optocoupler IC? The Complete Guide

Opto- refers to everything that has to do with light.  This means that these are light-controlled integrated circuits.

Optocoupler  ICs are integrated circuits that rely on light waves to provide the required electrical isolation in electric circuits while at the same time facilitating the flow of electric signals from one point of the circuit to another.

Optocoupler IC Image source ICRFQ

These chips are known by other names such as photocouplers, opto-isolators, and optical isolator  ICs.

The presence of light waves triggers the operation of the optocouplers.  They depend on the principle of photovoltaic effect.

Are you planning to buy optocoupler ICs for your business? This is a perfect guide for you. We are going to discuss in detail everything that you should know about these integrated chips.

By the end of this guide, you will know what optocouplers are, how they work, and their applications.  You will also be in a perfect position to choose the best optocoupler for your application, including buying from the right sources.

Construction of optocoupler ICs:  What are they made of?

Optocouplers exist in the form of integrated circuits. This implies that they are made of several electronic components connected to form complete circuits.

Each component has a specific role to play in the circuit.  They combine the functions and properties to execute specific tasks.

Since the working principle of these ICs depends on light, there must be a light source on the chip. In most cases, light-emitting diodes (LEDs) are used for providing the much-needed light.

Once the light has been illuminated, there must be a light receptor. This is where photosensors come in. They receive or sense light that has been emitted by the LED.

All the electronic components that make up an optocoupler IC are separated from each other by a dielectric material.

As integrated circuits, optocoupler ICs come in different form factors. These are surface mount (SMT), Through-hole, and leaded packaging types.

Each packaging that is used will depend on the specific application area of the optocoupler IC. This is because the packaging will dictate the compatibility of the chip with the electronic device. From the packaging,  you will be able to create connections with other components of the device. 

Working principle of optocoupler IC

 The principle operation of optocoupler IC is a result of a series of actions that take place in the circuit.

When the LED  is turned on, it will emit infrared light waves which will be detected by the photosensors.

The sensors will allow an electric current to flow to the output section of the electric circuit.

On the other hand, when the LED is off, no current will flow to the output. This implies that the LED is the main factor that determines the presence of electric current in the circuit.

 Based on this working method, it means that the two flowing electric currents or signals are isolated from each other.

 The light signals from the LED are made to cross the nonconducting barrier that is between the input and output sections of the IC chip. The separation of these two sections helps to create the necessary isolation. This protects the signals from noise and other external waves.

The light signals from the LED will eventually end on the photosensitive electronic component where they will trigger the conduction of electric current. The strength of the current will depend on the intensity of the light from the diode.

The output current or signal is usually connected to another electric circuit where it will trigger the desired action. Some output signals may be connected directly to the electric load while others may be used to trigger another set of signals.

Types of optocoupler IC

There are different types of optocoupler ICs. Usually, the classification will depend on the output type that is used on the IC.  Here are the most common types of optocoupler ICs that you should know:

Photocell IC

Photocell optocouplers are usually considered the earliest versions of optocouplers IC design. They are also known as opto-isolators.

Originally, photocell ICs used incandescent light bulbs as their main source of light. However, LEDs are now the preferred light source for these ICs.

They are mainly used for the  AC and DC operations and this is because of their non-polarized designs.

Photocell optocoupler ICs are considered obsolete and this is because they are slower than most options in the market.

Photodiode IC

In photodiode optocouplers, LEDs are used as the light source while photodiodes serve as light detectors.

They are considered the most popular types of optocoupler ICs and this is mainly because of their fast switching speed. However, they tend to have a low current transfer ratio.

The good thing about photodiodes is they can be easily modified to deliver better performance. This is done by outfitting the diodes with other components such as buffer amplifiers.

Phototransistor optocouplers

In phototransistor optocouplers, LEDs are still used as the source of light. Signals on the output circuits are controlled by either a bipolar phototransistor or a Darlington phototransistor. These transistors allow electric signals or currents to flow in one direction only.

Photo-TRIAC optocoupler IC

TRIAC optocouplers are also light-dependent ICs that are characterized by high-current transfer ratios. They are mainly used in high-voltage power applications. 

Advantages of optocoupler IC

Optocoupler chips have a wide range of applications in the modern world of electronics. Of course, there are many reasons why device manufacturers think it is important to include these chips in their applications.

Some of the advantages of optocoupler include:

· Small and light: Being integrated circuits, size will always be a key benefit when it comes to using optocoupler ICs. The small size of these chips means that they can be easily embedded into different devices to perform their functions.

· Fast switching: Optocoupler ICs have fast switching speeds, a factor that is mainly caused by the presence of transistors in the circuits.

· Minimum noise. The separation of the input and output signals helps to prevent noise in the circuit. This improves the accuracy and quality of signals generated by the optocoupler.

· Strong and durable: The solid construction of optocoupler ICs provides a lifetime guarantee of strength and durability.

· Low cost: manufacturers can easily produce optocoupler ICs in bulk. Of course, this has a direct impact on the cost of the products. They are quite cheap in the market, especially to the bulk buyers. Furthermore, optocoupler ICs are easily available.

What are the limitations of optocoupler IC?

One major limitation of optocoupler ICs is they require external biasing.  This is the only way that they can direct electric signals in the desired direction.

Most optocoupler ICs in the market cannot handle high electric current. Additionally,  despite having high switching speeds, the chips have poor response to the high frequency.

The good news is you can override these limitations by choosing optocoupler  ICs that are compatible with your applications.  You should also verify the quality of the IC to ensure that it is designed for performance. 

Applications of optocoupler ICs

Optocoupler ICs have a wide range of applications. The most notable ones include:

· Data communication especially in applications that rely upon light signals to  support the exchange of data between devices

· Sensors:  The operation of some sensors depends on the light signals. Optocouplers convert light signals to electric current which will trigger the desired actions. A perfect example is in the security systems.

· Power control and regulation where the chips are used for dictating the amount of power that is supplied to circuits. The regulation is determined by the intensity of light signals.

· Optical isolators: Optocoupler ICs are used for shielding light-sensitive devices from the effects of light.

· Switching in digital circuits and also in microprocessors.

So, what kind of electronic application are you building? Do you think it will need an optocoupler IC? Talk to us directly and we will help you choose the right type of optocoupler integrated circuit.

Buying from  the best optocoupler IC supplier in China

Now that you know all the essentials about optocoupler ICs, the next step is to buy the right ones for your application.

If you are into building electronic devices and appliances, there is a high chance that you would like to buy optocouplers in bulk.

This is where the importance of suppliers and distributors comes in. They can supply any volume of optocoupler that you need.

With the many suppliers in the market claiming to be providing the best-quality optocoupler ICs, you should be extra vigilant about which one you choose.

We at ICRFQ are ready to deliver the exact optocoupler ICs that you need for your electronic application.

We are a reputable electronic components supplier in China and optocoupler ICs are among the products that we stock.

We also stock many other types of integrated circuits for different applications.

With over 20 years of experience in this field and backed by an excellent customer support system, you can trust us for quality products and services.

 All you need is to contact us and we will ensure you get what you want. Being a global electronic component supplier, we deliver to all countries around the world.