4N35 IC : PinOut, Features, Specifications,Vs 4N25, Interfacing & Its Applications

The optocoupler is a reliable and versatile component, used in modern electronic systems which bridge the gap between electrical isolation & signal transmission. This is designed with a singular channel configuration by incorporating an IR LED & an NPN phototransistor. So it is perfect for applications requiring high-performance signal processing and robust electrical separation. The key attributes of an optocoupler mainly include maximum CE voltage, an isolation voltage, wide operating temperature, etc, So it is well-suited for relay driver circuits to feedback systems within SMPS, its adaptability continues to provide to the needs of designers and engineers which seeks reliable and efficient solutions. Thus, this article provides an overview of 4N35 IC, pinout, features, specifications, and applications.

What is 4N35 IC?

The 4N35 is an optocoupler IC, also called a photocoupler or optical isolator. It is available in both 6-pin SMD and DIP packages. This optocoupler IC includes two significant components: an IR LED and a phototransistor, where an IR LED drives a phototransistor. These optocouplers are utilized to connect two circuits exclusive of an ohmic contact.

So they permit one of the circuits to switch to another one when they are separated. The primary circuit is connected simply to the infrared diode whereas the secondary circuit is connected to the phototransistor. So the isolation ensures that no harm occurs in whichever of the circuits when the other circuit has any fault. An optocoupler is similar to a relay which separates two circuits magnetically but they vary with relays in size and permit fast operation.

4N35 Optocoupler IC Working

4N35 optocoupler IC working is straightforward because when the infrared LED in this IC is powered, the phototransistor notices infrared light which leads to transistor saturation (or) conduction. The phototransistor in this IC includes two bases where one base of this transistor is controlled, facilitating any photodetection (or) IR light detection. The other base is connected to the sixth pin of the IC which allows immediate control throughout both processes.

Thus, the 4N35 optocoupler IC works by changing an input signal into an electrical signal with the light. When an electrical signal is provided to the LED then it emits IR rays. So the phototransistor notices the light and generates an equivalent signal. This is an output signal which is directly (or) being amplified to a normal digital level.

This optocoupler IC operation is based on the electrical isolation principle, which means that the i/p and o/p terminals are isolated electrically because light is utilized as the transmission medium. So this procedure avoids electrical interference and allows it to be utilized within audio circuits.

4N35 IC Pin Configuration:

The 4N35 IC pin configuration is shown below.

                 4N35 IC Pin Configuration

• Pin-1 (Anode): It is an anode pin of Tx (IR LED) which provides a logical input signal to the inside IR.
• Pin-2 (Cathode): It is a cathode pin of IR LED that provides the infrared signal to make the common GND throughout the circuit and power supply.
• Pin-3 (NC): It is Not a Connected pin.
• Pin-4 (Emitter): It is an emitter pin of optocoupler. This is a GND pin for IR Rx in the IC & it is used to build the common GND through the circuit & power supply.
• Pin-5 (Collector): It is an output pin of the IR LED within the IC which provides the logical output by getting the IR signal.
• Pin-6 (Base): It is the base pin of an optocoupler which is a sensitive transistor pin that affects the timing behavior & CTR (current transfer ratio) of the optocoupler.

Features & Specifications:

The features and specifications of 4N35 IC include the following.

• 4N35 is an optocoupler IC.
• It is manufactured by onsemi.
• Its input type is DC.
• The output type is a transistor with a base.
• The mounting type is through-hole.
• The package or case is 6-DIP.
• Product status is obsolete.
• It has one channel.
• Voltage isolation is 5300Vrms.
• The maximum output voltage is 30V.
• Maximum Vce saturation is 300mV.
• The minimum current transfer ratio is 100% at 10mA.
• Typical forward voltage is 1.18V.
• The typical turn ON or OFF time is 2µs.
• The maximum DC forward current is 100 mA.
• It has one channel.
• The reverse voltage is 6V.
• Isolation voltage is 5300 Vrms.
• Power dissipation is 250 mW.
• Operating temperature ranges from -55°C ~ 100°C.

4N35 Optocoupler IC Design

The opto-coupler IC includes a gallium arsenide IR LED & an NPN silicon phototransistor. This IC handling is very easy and achieves preferred results. When this IC is used as a phototransistor, then pin-6 is not necessary.

The 4N35 optocoupler IC circuit is shown below so the connections of this IC follow as;

            4N35 Optocoupler IC Design

• The anode terminal of the IR LED or pin-1 is connected to the logic input.
• Connect the cathode terminal of the IR LED or pin-2 is connected to the GND.
• Pull up the pin-5 or collector pin of the transistor with a resistor and connect it to the o/p device.
• For the pin-4 or emitter pin is connected to a separate GND.
• Make sure that the emitter & the cathode terminal are not connected to the similar GND because they are intended to be isolated.

Working

Whenever a logic 0 input is provided to the IR LED, then the LED will be turned OFF. So the transistor triggering & the output obtained are HIGH across the CE terminal. Equally, whenever the LED gets logic 1 then it turns on by triggering the transistor & shorting the CE junction which results in low output. Thus, the voltage across the CE should not go beyond 30V.

Equivalents & Alternatives

Equivalent 4N35 ICs are; 4N3, 4N25, 4N3, 4N26, PC816、4N27, PC817, 4N36, H11Ax series, etc. Alternative4N35 ICs are; 6N137, H11L1, 4N35-500E, 4N35-X017, MCT2E, PC817, etc.

How to Operate 4N35 IC Securely for a Long Period in a Circuit?

To ensure the optimal performance and long-term stability of this IC in a circuit, it is suggested that should not operate beyond its maximum rating values. Avoid imposing (or) operating loads that go beyond 150mA through this device. It is recommended always to utilize current-limiting resistors in combination with the infrared LED. This IC must be operated at >-55 degrees Celsius and < +100 degrees Celsius while its storage must be maintained in temperatures >-55 degrees Celsius and < +150 degrees Celsius.

4N35 Optocoupler IC Interfacing with Arduino Board

The 4N35 optocoupler IC has a gallium arsenide IR LED & an NPN silicon phototransistor. Whenever the input signal is provided to the input terminal of LED then it lights up. Once the light signal is received then it changes it into an electrical signal & gives the signal directly (or) amplifies it into a typical digital level. So, the signal transition & transmission is completed. Since light is the transmission media then the input & the output terminals are electrically isolated, so this procedure is also called electrical isolation.

The required components of this interfacing mainly include; an Arduino Uno board, 4N35 optocoupler, 220Ω and 1kΩ resistors, USB, breadboard, jumper wires, etc. The connections of this interfacing follow as;

4N35 Optocoupler IC Interfacing with Arduino

The LED in this interface is the load that is connected to the NPN phototransistor.

• Pin 2 of the optocoupler IC is connected to pin 7 of the Arduino board.
• The pin-1 of the IC is connected to a 1K current limiting resistor and after that to 5V.
• Pin 4 of IC is connected to the GND terminal of the Uno.
• Pin-5 of the IC is connected to the cathode terminal of the LED and the anode is connected to 5V through a 220 Ohm resistor.

Code

The required code for this interfacing includes the following.

//Turn on a led by 4n35 optocoupler IC
//turn on the LED for half a second, then turn it off for half a second repeatedly.
int OptoPin=7;
//attach the input of the 4n35 to pin 7
void setup()
{
pinMode(OptoPin, OUTPUT); //set it as OUTPUT
}
void loop()
{
digitalWrite(OptoPin, LOW); //set the OptoPin as LOW level,then the led
connected on the output of 4n35 will be light
delay(500);
//delay 500ms
digitalWrite(OptoPin, HIGH); //turn off the led
delay(500);
//delay 500ms
}

Working

The 4N35 optocoupler breaks the connection between the signal source & signal receiver to stop electrical interference. So it is used to avoid interference from exterior electrical signals. This opto-coupler is used within AV conversion audio circuits.

In the internal structure of 4N35 IC, the pins 1 & 2 are connected to an IR LED. Whenever the LED is enabled then it emits IR rays. So to guard the LED from burning, generally 1K resistor is connected simply to pin-1. After that, the phototransistor is turned ON whenever it receives the rays. Thus this can be done to control the LED which is connected to the phototransistor.

In the above code, a LOW-level signal is provided to pin-7 of the IC, and then IR LED emits IR rays. After that, the phototransistor gets IR rays & gets electrified, and the cathode of the LED is LOW, then the LED will be turned ON. In addition, you can control the load through these circuits only by connecting pin 2 to GND and it will lighten.

4N25 vs 4N35

The 4N25 & 4N35 optocouplers belong to a similar family but they have several differences in terms of features, specifications & applications. The difference between 4N25 and 4N35 optocouplers includes the following.

Advantages & Disadvantages

The advantages of 4N35 IC include the following.

• The 4N35 optocoupler is a versatile IC.
• It is available in both 6-pin SMD and DIP packages.
• This IC is very pretty to use.
• They have less power consumption.
• It gives a good response at low frequencies.
• This optocoupler avoids interference from exterior electrical signals.
• These are cheaper and longer lasting.
• It is compatible with the common logic series.
• It separates input o/p output circuits electrically to protect sensitive components from harm caused by electrical surges or noise.
• This optocoupler is versatile and transfers both AC & DC signals to make it suitable for different electronic applications.
• It has high-voltage electrical isolation ratings like 1.5-kV, 2.5-kV (or) 3.55-kV.
• It has a 7 µs high-speed switching time and a high direct-current transfer ratio.

The disadvantages of 4N35 IC include the following.

• It requires external biasing voltage mainly for its operation.
• Its high-frequency response is very poor.
• Optocouplers are inefficient within low-power electronics.
• These can fail because of LED leakage current, interface contamination, thermo-mechanical stress, and breakdown voltage changes.
• They have propagation delays which limits data rates.
• They have non-standard logic gates mainly for input & output, thus the interface with the rest of the system may need extra components (or) design effort.
• It is very hard to incorporate various channels into a similar optocoupler package.
• They have temperature-dependent operating parameters & operating changes by device age.

Applications

The applications of 4N35 IC include the following.

• The 4N35 opto-coupler can be utilized for electrical insulation.
• It can be used within AV conversion audio circuits.
• This IC can be applicable in driving relays & motor circuits.
• It can be utilized for AC mains detection, reed relay driving, SMPS feedback, etc.
• It can be utilized for telephone ring detection, logic ground isolation, and logic coupling through higher-frequency noise rejection.
• The 4N35 optocoupler IC is used in various electronic circuits to protect circuits, components, and ICs from voltage spikes or surges that could harm them potentially.
• It can also be used to detect voltages within both AC & DC circuits at the o/p of microcontrollers and high-voltage equipment and control high-power transistors.
• It is used to detect AC power, phone ring signals, driving reed relays, etc.

Please refer to this link for the 4N35 Optocoupler Datasheet.

Thus, this is an overview of the 4N35 optocoupler which provides electrical isolation between both the input and output circuits. So it is made up of an NPN phototransistor & a gallium arsenide IR LED. So it protects very delicate components from potential injury because of noise or electrical surges. Thus, it can also allow AC and DC signal transmission by ensuring flexible usage in different electronic applications. The 4N35 IC is used in different applications like Electrical insulation, AV conversion audio circuits, I/O switching of microprocessors, and AC & DC power control. Thus, here is a question for you, what is H11L1 IC?