Isocom isp817 series optoisolators 1 channel 4 pin isocom isp817cxsmtr this optically coupled isolator has a current transfer ratio of 200 to 400 and is suitable for high density pcb mounting it utilises an ir led and npn silicon phototransistor to give a device with high isolation value and high current transfer ratio suitable for applications such as logic to logic isolators line receivers current level sensors ac to ttl conversion etc isocom isp817cxsmtr optoisolator 1 channel 20