The BZX79B20 R0 is a low power, 500 mW Zener diode from Taiwan Semiconductor. It is designed to provide voltage stabilization and protection from excessive voltage and current. The diode is rated at 20V to dissipate up to 500 mW of power and has a reverse breakdown voltage of 20 volts. The device is halogen-free and ROHS compliant, making it an environmental friendly option. The BZX79B20 R0 also operates within a temperature range of -55°C to 125°C.