The TLP521-4GB with Optocouplers DIP-16 RoHS is a low-profile high-speed phototriac coupler manufactured by Isocom. It is an integrated circuit (IC) optical isolator that is used to provide optical isolation between two independent circuits. It uses a low-power optical LED source to generate a light signal, which is optically coupled and then detected by a phototriac output stage. This particular device is RoHS compliant and comes in a 16-pin dual in-line package (DIP). It offers guaranteed noise-immunity values and a wide operating temperature range, making it suitable for a variety of applications. These applications include soft starters, industrial controllers, ventilators, HVAC systems, and AC load control.