S1ATR is a type of Surface Mount (SM) diode that is used in a variety of applications such as in telecommunications, power systems and electronics. It is a small, bidirectional diode made from Silicon (Si) P type material. It has a high reverse leakage current, and a low forward voltage drop. It is designed to be capable of withstanding transient voltages. This makes it suitable for circuit protection, fusing, and surge clamping in applications where high currents and voltage transients can occur.