The MMSZ4689T1G is a surface mount Zener diode from ON Semiconductor which is designed to maintain a constant voltage of 5.1V and provide maximum power dissipation of 500 milliwatts. It features a low forward voltage drop for higher efficiency in many applications, a maximum forward voltage of 1.2V for maximum current rating, and a maximum peak current rating of 1A. It has a voltage tolerance of ±5%, a wide temperature range of -65°C to +150°C, and can operate up to 0.3A for steady-state operation. It also provides excellent reverse leakage current characteristics. This part is available in a small SOT-23 surface mount package for easy mounting and assembly.