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4N35 IC Optocoupler Phototransistor IC

Specification	Details
Input Type	Infrared LED
Output Type	Phototransistor (NPN)
Isolation Voltage	3550V (RMS)
Collector-Emitter Voltage ($V_{CEO}$)	30V (Max)
Forward Current ($I_F$)	60mA (Max)
Package Type	DIP-6 (Through-Hole)

Price

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₹ 21.19

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Barcode: 14891498

Product Description

The 4N35 IC Optocoupler is a high-reliability electronic component designed to provide complete electrical isolation between two circuits while allowing signal transmission. It consists of an infrared-emitting diode (IRED) optically coupled to a monolithic silicon phototransistor in a compact 6-pin DIP package. The 4N35 acts as a "bridge" that passes information via light rather than electricity, making it an essential tool for protecting sensitive microcontrollers from high-voltage spikes, ground loops, and electrical noise. Whether you are interfacing an Arduino with a high-power AC motor controller or designing a medical device, the 4N35 ensures that a failure in the high-power section does not travel back to destroy your control electronics.

Key Features

High Isolation Voltage: Capable of withstanding up to 3550V RMS, providing a robust safety barrier for mains-powered industrial applications.
General Purpose Versatility: Compatible with standard logic families (TTL/CMOS), making it easy to integrate into digital and analog designs.
Fast Switching Response: Optimized for digital signal transmission with rise and fall times suitable for PWM and low-speed data communication.
Base Connection Pin: Pin 6 provides access to the phototransistor's base, allowing for fine-tuning of the switching characteristics and sensitivity.
Space-Efficient DIP-6 Package: Standard through-hole footprint that fits perfectly into 2.54mm breadboards and IC sockets for rapid prototyping.

Technical Details

Current Transfer Ratio (CTR): 100% (Minimum).
Collector Current : 100mA.
Operating Temperature Range: -55°C to +100°C.

Prototyping and Engineering Tips from Robogears

The "Input Resistor" Rule: CRITICAL: Just like a standard LED, the internal IR LED (Pins 1 & 2) requires a current-limiting resistor. If you connect Pin 1 directly to a 5V Arduino pin, the internal LED will burn out instantly. Use a 220-ohm to 470-ohm resistor for a 5V signal.
Wiring the Output: In most digital applications, the 4N35 is used in a "Common Emitter" configuration. Connect Pin 5 (Collector) to your target VCC (e.g., 5V) through a 10k ohm Pull-Up Resistor, and connect Pin 4 (Emitter) to the target Ground. Your isolated signal is then taken from Pin 5.
Ground Isolation: To achieve true "Optical Isolation," the ground of your input circuit (Arduino) must NOT be connected to the ground of your output circuit (Motor/Relay). If the grounds are joined, the optocoupler's safety benefit is bypassed.
Using Pin 6 (Base): For standard digital switching, Pin 6 is usually left unconnected. However, if you find the optocoupler is "too sensitive" or switching due to noise, you can connect a high-value resistor (100k - 1M ohm) from Pin 6 to Pin 4 (Ground) to stabilize the phototransistor.
AC Zero-Cross Detection: Because the 4N35 uses a single IR LED, it is commonly used in zero-cross detection circuits for AC dimmers. When the AC sine wave passes through zero, the IR LED turns off, creating a pulse that the microcontroller can use to time its firing pulses for a TRIAC.

Package Includes

1 x 4N35 IC Optocoupler Phototransistor IC

Disclaimer: Do not exceed the maximum collector-emitter voltage of 30V. This IC is intended for signal isolation; for switching high-power AC loads directly, use a Triac-output optoisolator (like the MOC3021) or a Solid State Relay. Always verify the pinout (Pin 1 is marked by a small dot/notch) before soldering to prevent damage to the internal IR diode.