The DG308BDJ part of Vishay is an optically coupled isolator. It is a surface-mountable and low-profile device consisting of two optically coupled elements – an infrared light-emitting diode and a NPN silicon phototransistor. It is designed for use in dc and ac inputs and isolates the load from the driver and power supply. The DG308BDJ is ideal for providing signal isolation, protection, and voltage isolation up to 5kV with a CTR (current transfer ratio) of over 500%. This device also has a wide operating temperature range of -40°C to +105°C and a fast switching speed of 100 nanoseconds.