Transistor Packages

TO-263 Package

Transistor Package TO-263 Surface Mount style, 3-Terminal

TO-263 Transistor Package TO-263 Transistor Metal Tab Side
TO-263 Plastic Case, Tab Mount

Tab mount. A type of package which provides a method of readily attaching one surface of the semiconductor device to a heat sink to achieve thermal management of the case temperature. Other factors that may effect the mounting include using thermal grease.
When attached to a PWB a copper pad should be located underneath the thermal tab of the TO-263 with a minimum size detailed in the data-sheet. Heat dissipation is conducted from the junction by the metal tab.

Package temperature. Case temperature is that temperature measured at a specified point on the case of a semiconductor device. The JEDEC specification will define the location of the thermocouple on the case.

TO-263 Transistor 3-Terminal Package drawing, top,side,back view
3-Terminal TO-263 Package Drawing

Devices using the TO-263 package styles;
N-Channel FETs: 2N7558, 2N7559, 2N7560.

Note that because the table of dimensions was taken from a government document relating to a FET, the table also lists the pin out. Pin 1; Gate. Pin 2; Drain. Pin 3; Source. Pin 4 Drain.
As with many of the packages of this type; when only three pins are required than the tab [pin 4] is also electrically connected to the high current lead, which also is normally connected to pin 2. In other words, in many cases, pin 2 is normally connected to pin 4 [the tab]. However it is always possible for the tab not to be electrically connected to any terminal and just used as a heat sink, or a thermal connection to a heat sink [a copper pad on the PCB].
Always check the data sheet to determine the function of the pins. This page is intended to show the size and shape of a TO-263 semiconductor package. The function of the terminals could change depending on the semiconductor molded into the package.

Transistor Package
Surface Mounted Header

TO-263 Package Dimensions
TO-220 Transistor Package Dimensions

Related topics:
Transistor Derating Guidelines
Including Thermal definitions

Types of Transistor cases
Manufacturers of FETs and BJTs
Thermal Compounds

D2PAC Package note;
2-lead TO-263 Package
3-lead TO-263 Package [this page]
5-lead TO-263 Package
7-lead TO-263 Package.

Note the location of the Thermal Pad.
The tab is electrically connected to the Drain.
Pin 2 may be missing in some cases.

Through-hole version of a TO-263 is a TO-220.
Or a TO-262 with bent leads.
TO-263 Power Resistor

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Modified 6/13/15
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