The Formosa BZT52C9V1S is a Zener diode that comes in a SOD-323 package and is compliant with the RoHS (Restriction of Hazardous Substances) standards. It is a small signal diode with a breakdown voltage of 9V and a maximum power dissipation of 500mW. It is designed to regulate the voltage in circuits, protect against overvoltage, and stabilize the current flow. It offers high reliability and low noise performance, making it suitable for a wide variety of applications.