The OSR51204C1E is an optocoupler manufactured by Optosupply. It is a 4-pin integrated circuit with dimensions of 6.90mm x 5.05mm. It is a micro-sized 4-channel phototransistor optocoupler with a dual-in-line package (DIP) configuration. The optocoupler features high common-mode transient immunity of greater than 55kV/µs, with a CTR min of 100% at 5V, and a CTR max of 1000% at 1.2V. The optcoupler also has a LED forward voltage of 1.2V, saturation voltage of 0.2V, and IFT of 1mA. It also has a rating of 5kVac (1min) and a receiver input voltage range of 6V. This component is often used in digital and analog transmission devices, such as microcontrollers, providing electrical isolation and signal transmission.