The MMSZ5254B is a single Zener diode with a voltage rating of 27V and a power rating of 500mW. It is designed for use in various electronic applications that require voltage regulation and protection. The diode has a forward voltage of 900mV @ a current of 10mA, and a reverse leakage current of 100nA @ a voltage of 21V. It has a tolerance of ±5% and an impedance of 41 Ohms. The MMSZ5254B is surface mountable, with a SOD-123F package. It operates in a temperature range of -65°C to 150°C. This Zener diode is part of the MMSZ5254 series from Taiwan Semiconductor, which is known for its high quality and reliability. With its excellent voltage regulation and low leakage current, the MMSZ5254B is an ideal choice for applications that require precise voltage control.