1N4748A is a Zener Diode made by Central Semiconductor (CDIL). It is a 1 Watt, 22V Zener Diode in a DO-41/Ammo Pack package. The reverse current of this diode is 5uA. This diode is designed for use in voltage regulation, standby power supplies, surge suppression and output rectification circuits. It is a popular choice for use in power supplies, voltage regulation and other applications due to its low cost, low power dissipation and good heat dissipation.