The TO-226 is a small type of plastic-molded "transistor outline" package commonly used for housing discrete devices such as transistors and thyristors as well as IC's with low lead counts such as voltage regulators.

The TO-226 has a flat front face that is marked with the device name or number, while its back is semi-circular in shape (see Fig. 1).  Since it is most often used in transistor packaging, the TO-226 usually has three leads, all of which protrude from the bottom of the package.  The typical lead pitch (distance between leads) of the TO-226 is 1.27 mm or 0.5 inch.

The TO-226 is structurally similar to the TO-92, but it is bigger than the latter because of its longer body.

Table 1. Properties of a Typical 3-Lead TO-226