TO-3 COMPONENT PACKAGE
TO-3 Component Package
Date Published: | |
Last Modified: |
Contents
1. Overview
Name | Transistor Outline 3 (TO-3) |
Synonyms |
|
Similar To | |
Mounting | TH |
Pin Count | 3, 5, 8, 15 (including the case) |
Pitch | 10.92mm (0.430") (TO-3-2L) |
Solderability | Easy to solder by hand. |
Thermal Resistance |
|
Package LxWxH | \(39.94x26.67=1065mm^2\) (smallest square area to enclose package) |
Typical PCB Land Area | n/a |
3D Models | |
Common Uses |
|
Variants:
TO-204 AA (TO-3-2L with 1.0mm pins)
TO-204 AD
TO-204 AE (TO-3-2L with 1.5mm pins)
TO-3-2L (2 pins + case)
TO-3-4L (4 pins + case)
This package comes in many variants with a different number of leads. The 2-lead device, called the TO-3-2L
is the most common. Variants exist with up to 15 leads[1]!
The TO-3 package has a very low junction-to-case thermal resistance (\(0.8-1.5^{\,\circ}{\rm C}/W\)). The TO-3 package is flange mount, which facilitates easy heatsinking. They are commonly screwed onto the metal enclosure of the device (you can sometimes see them on the outside of the enclosure!) for cheap and effective heatsinking.
Large heatsinks designed for the TO-3 package can have thermal resistances as low as \(0.4^{\,\circ}{\rm C/W}\). The thermal resistance between the device case and the heatsink is normally between \(0.5-1.7^{\,\circ}{\rm C/W}\).
2. TO-3-2
TO-3-2
is the variant of the TO-3
component package with 2 leads. K02A
is the National Semiconductor package code for the TO-3-2
package[1].
There are three sub-variants under the TO-3-2
banner[2]:
TO-204AA
: Standard TO-3-2 package.TO-204AD
: Thicker 1.27mm leads for higher currents.TO-204AE
: Even thicker 1.52mm leads for higher currents.

3. TO-3-8


4. TO-3-15
References
[1] Texas Instruments (2011). SNOA033: Metal Can Packages (TO-3/5/8/18/39/46/52/72). Retrieved 2021-11-08, from https://www.ti.com/lit/an/snoa033/snoa033.pdf.
[2] Wikipedia (2006, Dec 2). TO-3. Retrieved 2021-11-08, from https://en.wikipedia.org/wiki/TO-3.
Authors

This work is licensed under a Creative Commons Attribution 4.0 International License .
Related Content:
- TO-204 AA Component Package
- TO-204 AD Component Package
- TO-204 AE Component Package
- TO-23 Component Package
- TO-273AA Component Package