The BZX79B18 R0G is a RoHS (Restriction of Hazardous Substances) compliant Zener diode produced by Taiwan Semiconductor that is encased in a DO-35 package. It has a maximum power dissipation of 500 mW and is capable of regulating a maximum forward voltage of 18 volts, while its break down voltage is 18.6 volts at 2 mA. It has reverse stand-off voltage is 15.2 V and has a response time of 5 uS, with a leakage current of 25 nA. This Zener diode can operate over a temperature range of -55°C to +175°C. It is also RoHS compliant, which means it is free of hazardous substances like mercury, lead, hexavalent chromium, and others.