The TO-220 is a style of electronic package used for high-powered, through-hole components with pin spacing. 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 to mount the case to a heatsink, allowing the component to dissipate more heat than one constructed in a

TO-92 The TO-92 is a widely used style of semiconductor package mainly used for transistors. The case is often made of epoxy or plastic, and offers compact size at a very low cost. History and origin The JEDEC TO-92 descriptor is derived from the ori ...

case. Common TO-220-packaged components include discrete semiconductors such as

transistor A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...

s and silicon-controlled rectifiers, as well as

integrated circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

Typical applications

The 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 Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...

type of package. TO-220 packages can be mounted to a

heat sink A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is thermal management (electronics), ...

to dissipate several watts of

waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...

. On a so-called "infinite heat sink", this can be 50 W or more. The top of the package has a metal tab with a hole used to mount the component to a heat sink. Thermal compound is often applied between package and heatsink to further improve heat transfer. 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 conductivity The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low ...

. 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. A heatsinked TO-220 package dissipating 1 W 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 1 to 60 °C higher than the ambient temperature, depending on the type of heatsink (if any) used. 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).. The junction-to-case thermal resistance of the LM317 voltage regulator (National Semiconductors, page 5, TO200 version) is 4 °C/W. 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 module A power module or power electronic module provides the physical containment for several power components, usually power semiconductor devices. These power semiconductors (so-called dies) are typically soldered or sintered on a power electroni ...

s. When a 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. The junction-to-air thermal resistance of the LM317 voltage regulator (National Semiconductors, page 5, TO200 version) is 50 °C/W.

Variations

The TO-220 family of outlines is defined by the

JEDEC The Joint Electron Device Engineering Council (JEDEC) Solid State Technology Association is a consortium of the semiconductor industry headquartered in Arlington County, Virginia, Arlington, United States. It has over 300 members and is focused ...

organization. There are a number of variations on this outline, such as: *TO-220F, TO-220FP a 3 lead JEDEC outline which plastic encapsulates the entire body and mounting tab metal that are normally exposed providing electrical insulation which inevitably increases the package thermal resistance relative to the uninsulated metal tab version. *TO-220AB a 3 lead JEDEC outline *TO-220AC a 2 lead JEDEC outline 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 TO-220 footprint.

Common components that use the TO-220 package

The TO-220 case is found on semiconductor devices handling less than 100 amperes and operating at less than a few hundred volts. These devices operate at DC or relatively low (audio) frequencies, since the TO-220 package is not intended for devices operating at radio frequencies. In addition to bipolar, bipolar Darlington, and power

MOSFET upright=1.3, Two power MOSFETs in amperes">A in the ''on'' state, dissipating up to about 100 watt">W and controlling a load of over 2000 W. A matchstick is pictured for scale. In electronics, the metal–oxide–semiconductor field- ...

transistors, the TO-220 case is also used for fixed and variable linear voltage regulator integrated circuits, and for Schottky diode pairs.

National Standards

Related packages

*TO-257 is a

hermetically sealed A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers but, as technology advanced, it applied to a larger ca ...

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.

References

External links

TO-220 standard
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TO-220 outline drawing
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ON Semiconductor ON Semiconductor Corporation (stylized and doing business as onsemi) is an American semiconductor supplier company, based in Scottsdale, Arizona. Products include power and signal management, logic, discrete, and custom devices for automotive, c ...

TO-220AB outline drawing
- Vishay Intertechnology
TO-220FP (Full Pack)
- Amkor Technology {{Semiconductor packages Semiconductor packages