TO-92 (TO-226) Component Package

TO-92 (Transistor Outline 92) is a very common family of through-hole component packages for low-power through-hole transistors, MOSFETs, and linear regulators.

TO-92 (TO-226AA)

If a package is just labelled as TO-92, then it is most likely to be the “standard” variant, which is also known as TO-226AA.

A 3D render of the TO-92-3 component package.

Synonyms

• 29-11: On Semiconductor.
• TO-226AA: JEDEC name for the standard TO-92 package.
• TO-92: If any additional info is missing, it’s likely to be the standard TO-92 package.
• Z Package: Analog Devices.

Dimensions

Mounted height is typically 10mm (including body and enough space to get the through-hole legs mounted in the PCB).

Pitch is variable, depending on how you bend the legs. Commonly adjusted to 2.54mm.

Thermal Resistance

• $220^{\circ}{\rm C}/W$ (package only)
• $175^{\circ}{\rm C}/W$ (plated through-holes)
• $145^{\circ}{\rm C}/W$ (plated through-holes and $0.25inch^2$ pad per lead)

TO-92/18 (TO-226AB)

The TO-92/18 variant of the TO-92 package is similar to the standard package (which is just called the TO-92), except that it has a longer body. It is also known as the TO-226AB or TO-92MOD package.

A 3D render of the TO-92/18 (TO-226AB) component package.

Pin Numbering

Pin numbering is always done from left-to-right, when the flat side of the TO-92 package is facing you and the legs are pointing downwards, as shown in the following diagram:

A 3D render of the TO-92 component package with pin numbering.

This is applicable to both the standard TO-92 (TO-226AA) and TO-92/18 (TO-226AB) variants.

Standard Pinouts

The pinout for JEDEC-named 2N series transistors is standardised as per the following table:

Pin Number	BJT Connection
1	Emitter (E)
2	Base (B)
3	Collector (C)

Heatsinks

There are a limited range of heatsinks available for the TO-92 component package. Aavid Thermalloy makes two TO-92 heatsinks, one of which is currently available (as of May 2016) on DigiKey.

The TO-92 clip-on heatsink by Aavid Thermalloy (part num. 575200B00000G).

Similar To

• TO-226