The 4N30M is a general-purpose photodarlington optocoupler designed to provide electrical isolation between input and output circuits. It consists of a gallium arsenide infrared emitting diode optically coupled to a high-gain silicon photodarlington detector. This device features high sensitivity to low input drive current, with a minimum current transfer ratio (CTR) of 100% at an input current of 10 mA. The optocoupler provides an input-to-output isolation voltage of 4,170 VACRMS for one minute. Common applications include low power logic circuits, telecommunications equipment, solid-state relays, and interfacing coupling systems of different potentials and impedances.