TO-220 is a style of electronic component package , commonly used
for discrete semiconductors as transistors and silicon-controlled
rectifiers , as well as integrated circuits . The "TO" designation
stands for "transistor outline".
TO-220 packages have three leads.
Similar packages with two, four, five or seven leads are also
manufactured. A notable characteristic is a metal tab with a hole,
used in mounting the case to a heatsink . Components made in TO-220
packages can dissipate more heat than those constructed in TO-92
* 1 Typical applications
* 2 Variations
* 3 Common components that use the
* 4 Related packages
* 5 See also
* 6 References
* 7 External links
TO-220 package is a "power package" intended for power
semiconductors and an example of a through-hole design rather than a
surface-mount technology type of package.
TO-220 packages can be
mounted to a heat sink to dissipate several watts of waste heat. On a
so-called "infinite heat sink", this can be 50W or more. The top of
the package has a metal tab with a hole used in mounting the component
to a heat sink.
Thermal compound is often applied to further improve
heat transfer from the package to the heatsink.
The metal tab is often connected electrically to the internal
circuitry. This does not normally pose a problem when using isolated
heatsinks, but an electrically-insulating pad or sheet may be required
to electrically isolate the component from the heatsink if the
heatsink is electrically conductive, grounded or otherwise
non-isolated. Many materials may be used to electrically isolate the
TO-220 package, some of which have the added benefit of high thermal
In applications that require a heatsink, damage or destruction of the
TO-220 device due to overheating may occur if the heatsink is
dislodged during operation.
TO-220 package that is heatsinked, dissipating 1W of heat, will
have an internal (junction) temperature typically 2 to 5 °C higher
than the package's temperature (due to the thermal resistance between
the junction and the metal tab) and the metal tab of the TO-220
package will typically have a temperature of 1 to 60 °C higher than
the ambient temperature, depending on the type of heatsink (if any)
The junction-to-case thermal resistance of a
TO-220 packaged device
(which typically matters less than the case-to-ambient thermal
resistance), depends on the thickness and the area of the
semiconductor die inside the package, typically in a range between 0.5
°C/W and 3 °C/W (according to one textbook) or 1.5 °C/W and 4
°C/W (according to another).
If more heat needs to be dissipated, devices in the also widely used
TO-247 (or TO-3P) package can be selected. TO-3P has a typical
junction-to-ambient (heatsink) thermal resistance of only about 40
°C/W, and its TO-3PF variant a slightly lower one. Further increase
of heat dissipation capability is possible with power modules .
TO-220 package is used without a heatsink, the package acts as
its own heatsink, and the heatsink-to-ambient thermal resistance in
air for a
TO-220 package is approximately 70 °C/W.
TS7805 linear voltage regulator in a
TO-220 variant package with
electrically isolated tab.
TO-220 outline is defined by the
There are a number of variations on this outline, such as:
* TO-220F, which has an insulated tab and body, and typically has a
higher thermal resistance than the metal tab versions.
Sometimes the designation is followed by the number of leads, as in
TO-220AB-5L for five leads, etc.
There also some vendor-specific variations such as International
Rectifier 's SUPER-220, which dispenses with the hole in favor of
clip-mounting, thus claiming TO-247-like thermal performance in a
COMMON COMPONENTS THAT USE THE
* 7805 , +5 V linear voltage regulator
* 7812 , +12 V linear voltage regulator
* LM317T , adjustable linear voltage regulator
* LM340, linear voltage regulator
* IRF510, N-channel MOSFET (5.6 A, 100 V)
* TO-257 is a hermetically sealed metal package that is otherwise
considered equivalent to TO-220.
* TO-220F also known as the SOT186 and SC67 is
TO-220 like package,
where the heatsink mounting tab has been encased in the plastic.
TO-3 , a metal case used for power semiconductors
TO-263 , the surface mount equivalent of the TO-220.
Chip carrier , Chip packaging and package types list
* ^ A B C "
TO-220 family package specification" (PDF). JEDEC
. March 24, 1987. Archived from the original (PDF) on June 18, 2017.
* ^ List of semiconductor cases,
* ^ Torque Recommendations for
* ^ "MC7800, MC7800A, NCV7805" (PDF). ON Semiconductor. Retrieved
24 May 2014.
* ^ A B Yong Liu (2012). Power Electronic Packaging: Design,
Assembly Process, Reliability and Modeling. Springer Science &
Business Media. p. 188. ISBN 978-1-4614-1053-9 .
* ^ A B Mike Tooley (2006). Electronic Circuits: Fundamentals and
Applications (3rd ed.). Routledge. p. 353. ISBN 978-0-7506-6923-8 .
* ^ Yong Liu (2012). Power Electronic Packaging: Design, Assembly
Process, Reliability and Modeling. Springer Science & Business Media.
p. 184. ISBN 978-1-4614-1053-9 .
* ^ List of package types,
* ^ http://www.irf.com/technical-info/appnotes/an-1000.pdf
* ^ "Power MOSFETs and IGBTs", Bill Travis, EDN: " and the TO-257
is a hermetic TO-220."