Optocoupler IC Distributor in China

RANTLE Optocoupler IC consists of a high output light emitting diode coupled with a high-gain and high-speed photodetector. These optocoupler ICs comes with inverter logic type (open collector output).

RANTLE Optocoupler IC features 1 Mbps typical data transfer rate and ±10 kV/µs (minimum) common-mode transient immunity. These photocoupler provide 5000V high isolation voltage that satisfies the reinforced insulation class according to international safety standard.

RANTLE Optocoupler IC are available in the SO6L package that contributes to system size reduction. Typical application includes intelligent power module signal isolation, factory automation (FA), and industrial inverters.

RANTLE Optocoupler IC have single-channel open-collector output in a stretched SO8 footprints. The device uses an insulating layer between the light emitting diode and an integrated photon detector to provide electrical insulation between input and output.

Additionally, RANTLE offers Optocoupler IC that are designed for reliable high-insulation voltage and high-noise immunity. They consist of an aluminum gallium arsenide light emitting diode and an integrated high-speed photodetector.

And also, we have RANTLE optocoupler IC that is advanced 2.5A output current IGBT drive optocoupler capable of driving medium-power IGBTs with ratings up to 1200V and 150A. It is suited for fast-switching driving of power IGBTs in motor control inverter applications and high-performance power systems.

RANTLE is an independent Optocoupler IC distributor for the leading manufacturers. With almost 15 years of experience distributing electronic components, we assure you the best optocoupler IC with a high-quality standard, fast delivery, authentic service, excellent credit and reasonable price.

We promise that RANTLE East Electronic is your most trustworthy and reliable optocoupler IC supplier!

We warmly welcome people from all over the world to contact and cooperate with us. We will become long-term business partners and build a splendid future together.

If you are interested of our one of a kind optocoupler IC, feel free to  contact with us.

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Optocoupler IC: The Ultimate FAQs Guide

Before importing Optocoupler ICs, probably you could be having many unanswered questions.

Today’s guide explores all the basic and advanced concepts on Optocoupler integrated circuits.

Whether you want to know the components, working principle, applications, classification criteria or testing mechanism – everything is in this guide.

What is an Optocoupler IC?

An Optocoupler integrated circuit is an electronic component that links two individual electrical circuits using a light-sensitive optical terminal.

Optocoupler IC

Basically a photocoupler is a semiconductor gadget that utilizes a short optical path to link a signal from an electrical circuit to another. At the same time, it provides electrical isolation.

The elementary design of a photocoupler IC comprises of an LED that emits infrared light and a photo-sensitive gadget that is utilized to sense the radiated infrared light.

Both the photo-sensitive gadget and LED are housed in a light-tight package having metal legs vital for the electrical coupling.

Optocoupler ICs find wide applications than may be imagined at first sight.

You can use them in a number of different innovative ways offering optical connection between circuitries.

This can be applied to transmit data, electrically isolate two circuits, or detect a break on the connection.

Whatever manner you use them; they offer a crucial function in many electronic circuits.

Which are the components of Optocoupler IC?

The opto-coupler integrated circuit is an electronic component consisting of two elements needed for electrical isolation:

Components of Optocoupler IC

Light emitter: This is found on the input part and receives the incoming signal and changes it to a light signal. Usually the light emitter comes as a light-emitting diode.

Light detector: This senses the radiated light beams from the emitter and transforms it back to the original electrical signal.

There are different types of light detectors, including a photodarlington, photodiode, phototransistor, among other devices.

The light detector and emitter are customized to complement each other, having equivalent wavelengths so as to ensure the attainment of maximum coupling.

In addition, the optocoupler IC may as well have other circuitry, for instance it may consist of the LED series resistor coupled with the driveability for the diode. Moreover, it may equally have an output amplifier.

What are the applications of the Optocoupler IC?

Photocoupler ICs have several functions within electronic and electrical circuits:

• Used to connect data between two circuits.
• Used inside optical encoders, where photocoupler IC offers a medium of sensing observable edge transitions on the wheel of an encoder to sense position.
• Used in several other circuitries where optical transitions and links are required.

Furthermore, they make part of the vital components in solid state relays.

In this circuitry, optocoupler IC is employed to electrically separate input and output, while allowing switching ON of output as per the input state.

Therefore, photocoupler ICs are found in an exceptionally great number of circuits.

Is there a difference between Optocoupler and Opto Isolator IC?

The terms optocoupler, opto-isolator and photocoupler are frequently applied interchangeably in electronics and technical publications.

That is, when citing components that perform the same function.

Strictly, there exist differences between the names opto-isolator and optocoupler.

The differentiating factor between the two terms is the variation in voltage required between the input and output:

Opto-coupler IC: It transfers digital or analogue data between circuitries while sustaining electrical isolations at potentials extending to 5000 volts.

Opto coupler IC

Opto-isolator IC: This is commonly utilized in power systems.

It transfers digital or analogue data between circuitries where the potential difference is beyond 5000 volts.

Opto Isolator

This is a rough overview of the differences between opto-isolator IC and optocoupler IC, Nevertheless, the terminologies are still widely applied interchangeably.

What are the Steps in Optocoupler Circuit Design?

Here are the key steps to follow when designing an optocoupler circuit:

i. Choose a Circuit Structure

Do not make a very complicated circuit. Having a circuit design with lesser components is advantageous in two ways.

The first reason is definitely based on cost, as it will reduce cost of production.

Secondly, having an optocoupler circuit structure with lesser components results in higher circuit reliability and minimizes the total failure rate.

ii. Choose Optocoupler Components

When selecting components of optocoupler IC, it is important to factor in your intended application.

In case you intend to use the photocoupler as a switch, you need to select one having higher minimum current transfer ratio.

However, when it is to be used in linear application, you can design an optocoupler having a restricted CTR range.

A restricted CTR will mean a smaller variation.

In case your optocoupler IC is to be subjected to extreme surrounding temperatures, choose one having a CTR that the ambient temperature will not have much effects on.

You should note that the CTR of a photocoupler IC will reduce with rising temperatures.

iii. Set Circuit Operation

In this step, you have to establish the circuit’s operating point. For you to understand this part, let’s use the circuit below as reference.

Circuit operating point

· Establish Output Level

It is possible to configure the above circuit to operate at both saturation and linear regions. The Vout value is zero at saturation whereas it is below Vcc but above zero in linear.

Without any bias on the diode side, the level of Vcc is equal to Vout.

Therefore, in case you are designing the optocoupler circuit to function as a switch, you need to configure a zero Vout or VCE when the photocoupler is conducting.

On the other hand, you should establish a specific level within the Vout node to be utilized as output level in the design if it is a linear application.

· Establish Rf Value

You can freely select this value, nonetheless, you should be careful in some application.

In most cases, you derive Vdd from digital device or circuit such as DSP or MCU.

If otherwise, determine the Rf value in such a manner making sure you do not exceed the current rating of the circuit or device.

For DSP and MCU, the source and sink currents are normally spanning from 4mA to 9mA, with some going above 9mA.

Therefore, it is always advisable to confirm in the datasheet.

Presuming the current rating is just 4mA maximum, preset the actual forward current at maximum 80 percent of it.

What is the Function of Optocoupler Relay?

Opto coupler relay

Optocoupler relays are employed in various fields as electronic switches to regulate DC or AC power.

They apply optocoupling technology as the principle of their functioning.

It is because they are needed to give high degree of isolation and resistance between the output and input circuits.

Also known as solid-state relays, photocoupler relays are often used in applications involving power of higher levels.

In most cases, they are used for interfacing levels of current of down to tens of amps and above and voltage amounts of as far as hundreds of volts and beyond.

Photocoupler relays comprise of the additional circuit – they are normally a full circuit block.

You may find them having drive circuit for the opto-transmitter LED and transient and surge protection circuit on the output.

For AC applications, certain optocoupler relays offer zero cross-switching for AC signals.

In this scenario, the output gadget only turns ON when the AC waveform goes across the zero volt position.

This is instrumental in minimizing electromagnetic interference.

How many types of Optocoupler IC are there?

There are a number of various types of optocoupler ICs available in the market. This is based on their requirements and switching abilities.

However, there exist four general types of photocooplers, each coming with an infrared LED but having different photo-sensitive gadgets.

The four main types of opto-isolator ICs consist of:

· Photo-transistor Optocoupler

The type of transistor in this type of photcoupler can either be NPN or PNP.

Phototransistor optoisolator ICs are further classified into two types based on the availability of output pin.

K847PH, LTV817, PC816 and PC817 are some of the common types of photo-transistor optocoupler ICs. 

This photocoupler types are mainly used in electrical isolation in DC circuits.

It is advisable to know the transistor maximum ratings before you use a photo-transistor opto-isolator IC.

· Photo-darlington Optocoupler

Darlington Transistor is dual transistor photocoupler IC, where one of the transistors is in control of the other transistor base.

They are 6-pin optocoupler and are also used for electrical isolation in DC circuits.

Connected internally to the transistor base, the sixth pin is helpful in controlling the transistor sensitivity.

H21B1, H21B2, H21B3, 4N32, and 4N33 are some of the examples of photo-Darlington optoisolator ICs.

· Photo-SCR optocoupler

Silicon controller rectifier, commonly abbreviated as SCR is also known as Thyristor.

Just like other types of optocouplers, the LED in photo-SCR optoisolator emits infrared, whose intensity control the SCR.

This optocoupler IC type is normally applied in AC circuitry.

IL400, MOC3071 and MOC3072 are some examples of photo-SCR photocoupler IC.

· Photo-triac Optocoupler

Photo-triac optocoupler IC is as well used for electrical isolation in AC type of circuitry such as lamps and motors.

This type of optocoupler IC is equally able to conduct both sides of an AC circuit with no-crossing detection.

This facilitates full supply of power to a load without any serious current spikes during inductive loads switching.

Examples of photo-triac optoisolator ICs include IL420 and 4N35.

However, there exist many other types of source-sensor combinations like LED-LASER, LED-photodiode, lamp-photoresistor combinations, slotted and reflective optocoupler ICs.

How does an Optocoupler IC work?

Current flow from the source signal passes across the input LED which radiate infrared light magnitude is equivalent to the electrical signal.

This radiated light falls on the bottom of the phototransistor, triggering it to turn ON and transmit in the same manner as an ordinary bipolar transistor.

You can leave the phototransistor base connection open for maximum responsiveness to the IR light energy of the LED.

Alternatively, you can connect the phototransistor to ground using an appropriate external resistor of high value to regulate the switching sensitivity.

This will make the phototransistor more stable and unaffected by false activation by voltage transients or external electrical noise.

When you interrupt the current flowing across the LED, it cuts off the infrared radiated light, making the phototransistor to stop conducting.

The phototransistor in the optocoupler IC can be used for current switching in the output circuit.

The spectral reaction of the phototransistor and the LED are closely monitored.

You can achieve electrical isolation as far as 10 kV, due to the fact that there exist no straight link between the input and out of a photocoupler IC.

What does Current Transfer Ratio CTR mean in an optocoupler IC?

Current Transfer Ratio (CTR) stands for the gain of the photocoupler IC.

It is the ratio of current of the phototransistor collector to the forward current of the infrared diode.

CTR = (IC / IF) * 100 and the value is always denoted as a percentage.

The CTR of an optocoupler IC depends on operating temperature, the forward current via the IR LED, the voltage supplied to the transistor and transistor current gain.

What are the Advantages of Optocoupler IC?

• Ensures protection of the control circuits because of electrical isolation.
• Guarantees transmission of wideband signal.
• Noise coming from the output section does not get integrated to the input section because of the unidirectional transfer of signal.
• It is easy to interface with logic circuits.
• It is a light weight and small size device.

How is an Optocoupler IC used in SMPS Circuit?

Optocoupler ICs are commonly used for galvanic separation in switch-mode power supplies SMPS.

They are used galvanic isolation of the primary side from the secondary side and also from the feedback generator.

The design of SMPS power converter depends on feedback around their output voltage to sustain control.

This feedback signal usually goes through a photocoupler IC placed between the main and the auxiliary sides.

What is the difference between 4n28 and 4n35 Optocoupler?

The 4N35 is a general purpose application optocoupler IC.

It comprises of a silicon NPN phototransistor and gallium arsenide infrared LED.

In 4N35 photo-coupler, a phototransistor is driven by an infrared emitter diode. 

It is widely employed as a general opto-isolator IC for electrical isolation to inhibit interference due to external electrical signals. 

However, 4N35s are normally utilized in linking a computer’s parallel port with an electronic circuit.

4N28 IC on the other hand is an industry conventional single channel photocoupler. 

This type of optocoupler comprise of a silicon NPN phototransistor and gallium arsenide IR LED.

There is electrical isolation of the primary and secondary circuits in the integrated circuit.

The pair phototransistor and diode is there to offer optical trigger medium between the secondary and primary circuit.

4N28 is a 6 pin optocoupler IC which can be found in a number of packages. Essentially you utilize only 4 pins but can utilize up to 5 pins.

How do you use 4n28 Optocoupler IC?

4N28 Optocoupler

As you now know, 4N28 photocoupler integrated circuit is made up of two components.

They include photo-transistor and infrared diode.

When using this opto-isolator, you connect the phototransistor at terminals 4, 5 and 6, whereas you connect the IR diode at terminals 1 and 2.

What are the Factors to consider when ordering for Optocoupler IC?

There are a number of specifications and parameters that you should take into account when ordering for an opto-isolator IC:

· Current Transfer Ratio, CTR:

A photo-coupler’s current transfer ratio is one of the essential specifications that you must look for when shipping the equipment.

CTR is the ratio of current flow in the output equipment divided by the input device current. There will be variations in CTR based on the type of opto-isolator utilized in the output.

Photo-darlingtons will have much higher CTR than conventional optocouplers.

Current transfer ratio values may range from 10% to 5000%.

However, you should note that the values tend to differ depending on the current level of the input.

Even though CTR value will differ based on the device, for most optocoupler ICs it will climax for input current levels of approximately 10mA.

· Bandwidth

It is essential to understand the bandwidth so as to know the maximal data rates that is suitable for an optocoupler IC. Most of phototransistor optocouplers have bandwidths falling in the 250 kHz region, whereas the photodarlington type may be a tenth of this value. Nevertheless, there exist much faster opto-isolators. Usually the lower the current transfer ratio, the faster the fall and rise times.

• Input current

This is the needed current by the transmitter device, usually the LED. The value is instrumental in calculation of the series resistor utilized to control the current.

• Maximum voltage of out device

In optocoupler ICs utilizing transistors, the maximum voltage will be equivalent to the VCE (maximum) of the transistor.

On the other hand, you should apply the equivalent rating for photo-coupler ICs utilizing other gadgets in the output.

Moreover, remember to retain an appropriate margin since it is not recommended to operate opto- isolator ICs near their maximum ratings.

Which are the different Packages used for Optocoupler IC?

There exist a range of different packages utilized for optocoupler ICs.

A variety of packages exist for photo-coupler ICs utilized for lower voltages.

They are usually in small packages.

Normally, they can be same, but not often similar to the common Dual-In-Line (DIL) integrated circuit packages for ordinary mount components.

Additionally, there are SMD versions like the Small Outline IC (SOIC) packages. They offer very compact alternative for packing the optocoupler ICs.

Nonetheless, you should make sure they meet they satisfy the necessary isolation requirements.

Conversely, there are various packages for opto-isolator ICs used for much higher voltages.

These type of photocoupler ICs can be found in a broad range of package style consisting of cylindrical, rectangular and specialty designs.

These types of packages are designed to offer higher isolation voltages compared to SMD packages like the SOIC and DIL.

What are the difference between Single State Relay and Optocoupler?

The primary difference between optocoupler and single state relay is that photocouplers are used in low power applications.

In contrast, single state relays are used for applications requiring higher amounts of power.

Typically, single state relays are employed to step up levels of current as far as tens of amps and voltage levels as far as hundreds of volts.

Optocoupler ICs are often contained inside small integrated circuit packages either as leaded semiconductor or surface mount gadgets.

Contrarily, single state relays are generally held inside much bigger packages, commonly requiring to be fastened to a heat sink.

In addition, they usually come with screw contacts to offer the needed current carrying ability.

What are the Main Information that must be in an Optocoupler IC datasheet?

Generally, all optocoupler datasheets have the following details:

• Description
• Features
• Applications
• Ordering information
• Agency approvals
• Electrical characteristics
• Absolute maximum ratings
• Current transfer ratio (CTR)
• Typical static graphs
• Switching characteristics
• Typical dynamic graphs
• Insulation and safety ratings
• Packaging, markings and packaging dimensions

How can you Test Optocoupler IC?

Optocoupler ICs

Method 1

In this method of testing photo-coupler IC, you will need the following gadgets:

• Ohm meter or multimeter
• Power supply or battery
• Push button
• 100 Ohm resistor
• Optocoupler

1. Switch ON the Ohm meter or multimeter and choose Resistance mode.
2. Connect the Ohm meter or the multimeter between the collector and emitter such that black probe connects to the emitter while red probe connects to the collector.

• Link the 100 Ohm resistor in series with the anode of the LED and switch ON the power supply.

2. Press down the push button and begin raise the voltage from zero to 2.5 volts.

On the multimeter or Ohm meter, you should observe a decrease in output resistance with increasing input voltage and vice versa.

1. If the multimeter behaves as in step (iv) then you have a good optocoupler IC but if otherwise, the photo-coupler IC is bad.

Method 2

In this case, you will require the following devices: Ohm meter or multimeter, 100 Ohm resistor, battery or power supply, push button and optical-isolator.

1. Switch ON the Ohm meter or multimeter and choose DC Voltage mode.
2. Link the push button and 100 Ohms resistor in series with the anode of the LED anode, then give the circuit power supply of +5V DC.

• When you press the push button, the displayed voltage reading should be about 0V to 0.2V DC.

On the other hand, when the push button remains unpressed, the displayed voltage reading needs to be about 5v to 4.9V.

1. If you make these observations in step (iii) then you have a good optocoupler ICand vice versa.

 Method 3

Here, you will require Ohmeter or multimeter, 100 Ohm resistor, power supply or battery, push button and optocoupler.

• Switch ON the ohm meter or multimeter and choose DC Voltage mode.
• Connect the push button and 100 Ohm resistor in series with the anode of the LED, then give the circuit a power supply of +5V DC.
• The LED will turn ON if you press the push button but will stay OFF if the push button remains unpressed.
• You have a good optical-isolator when you make the observations in step (iii). But if otherwise, then the photo-coupler is bad.

Are there Quality Standards for Optocoupler ICs?

There exist a number of broadly accepted standards that regulate the making and testing of electronic machines.

Probably the most commonly known standard is the Underwriter’s Laboratories (UL). It has two kinds of certification: UL-recognition and UL-listing.

The “UL Recognized” label, optionally branded on the equipment themselves, designate parts that have been assessed to a certain degree by the UL.

They will undergo further review by the UL for formal incorporation into the final device.

A “UL Listed” label is put on complete equipment.

Therefore, let’s look at the main standards that exclusively deal with the fabrication and testing of optocoupler ICs.

These fall under two key standards, IEC 60747-5-5 and UL1577.

· UL 1577 Standard

This standard mainly applies in the United States and it mainly deals with safety specifications related to optocouplers.

UL1577 primarily covers corrosion protection, thermal testing, spacing, package fabrication issues and materials among other features of the optocoupler IC.

· IEC 60747-5-5 Standard

The primary role of this standard is to ensure safe isolation from photo-couplers.

To conform to the IEC 60747-5-5 standard, optical-isolators must first stand a chain of mechanical and environmental stresses.

After that, they go through a sequence of electrical compliance tests.

· RoHS Compliance

This is a product level conformity Directive 2002/95/EC of the European Union, which restricts the use of specific hazardous material in electrical and electronic devices.

Optocoupler ICs conforming to this directive do not surpass the allowable quantities of the following substances: cadmium, lead, hexavalent chromium, mercury, polybrominated diphenyl ethers (PBDE), polybrominated biphenyls (PBB), with a few limited exceptions.

I hope you have learned a lot about Optocoupler ICs.

In case you have any questions, feel free to contact Rantle team.

We distribute and offer free consultations on IC chips and memory ICs.