4N35 Optocoupler Phototransistor IC is an infrared emitter diode drives a phototransistor. They are also known as opto isolators since they separate two circuits optically. The 4N35 optocoupler consists of gallium arsenide infrared LED and a silicon NPN phototransistor.

These are used to couple two circuits without any ohmic contact. They allow one of the circuits to switch another one while they are completely separate. The first circuit is connected to IR diode while the other circuit with the phototransistor. The isolation ensures that no damage occurs in either of the circuits while the other one has a fault.

Features:

Gallium-Arsenide-Diode Infrared Source Optically Coupled to a Silicon npn Photo-transistor
High Direct-Current Transfer Ratio
High-Voltage Electrical Isolation 1.5-kV, 2.5-kV, or 3.55-kV Rating
High-Speed Switching tr = 7 µs, tf = 7 µs Typical
Input-to-output peak voltage (8-ms half sine wave)4N35= 3.55 kV
Input-to-output root-mean-square voltage (8-ms half sine wave)4N35= 2.5 kV
Collector-base voltage=70 V
Collector-emitter voltage=30 V
Emitter-base voltage=7 V
Input-diode reverse voltage=6 V
Input-diode forward current: Continuous 60 mA
Typical Applications Include Remote Terminal Isolation, SCR and Triac Triggers, Mechanical Relays and Pulse Transformers

Specifications:

Symbol	Parameter	Value	Unit
VR	Reverse voltage	6	V
IF	Forward current	60	mA
IFSM	Surge current	2.5	A
Pdiss	Power dissipation	100	mW
VCEO	Collector-emitter breakdown voltage	70	V
VEBO	Emitter-base breakdown voltage	7	V
IC	Collector current	100	mA