The DO package, DO stands for Diode Outline, is a standardized package format for diodes. It has a cylindrical structure, is made of glass, plastic or metal and is used for small- signal and for power diodes.
The Diode Outline Package comes in various designs and types such as DO-5, DO-8, DO-9, DO-35, DO-41 and DO-201 to name a few. The packages for power diodes, such as DO-9, have a package with good heat dissipation and are provided with axial lead wires. This type of package is used for rectifiers, regulators and other power circuits, among others.