Vishay, SFH618A-3 Phototransistor Output Optocoupler, Through Hole, 4-Pin DIP

The Vishay SFH618A coupler feature a high current transfer ratio, low coupling capacitance and high isolation voltage. These couplers have a GaAs infrared diode emitter, which is optically coupled to silicon planar phototransistor detector, and is incorporated in a plastic DIP-4 package. The coupling device are designed for signal transmission between two electrically separated circuits.

Good CTR linearity depending on forward current
Low CTR degradation
Low coupling capacitance