The Isocom Components 2004 LTD Optoisolators - Transistor, Photovoltaic Output IS281D is a DC input NPN phototransistor output optocoupler built to be used in surface mount applications. This optocoupler is designed specifically with 4-pin SMD configurations, making it suitable for more compact designs where space is limited. In addition, the IS281D provides that users with reliable isolation, enabling them to safeguard and protect their electronic equipment from dangerous signals or erroneous ground paths. This optocoupler is also highly reliable and undergoes multiple tests for safety and efficiency. The internal structure of the IS281D ensures that it is suitable for a variety of industrial and consumer applications, making it a great choice for those who need a reliable and efficient optocoupler.