Transistor Package; TO-92 Case style, Plastic Package
Transistor Outline Package
TO-92 Terminal identification
FETs may also be found in this package.
TO-92 Plastic Body
TO-92 is a through-hole device in a plastic case.
Terminal identification [BJT]; Pin 1 Emitter, Pin 2 Base, Pin 3 Collector.
Terminal identification [Shunt Regulator]; Pin 1 Reference, Pin 2 Anode, Pin 3 Cathode.
Note the location of the flat portion of the case to the pins.
Press-fit Aluminum heat sinks are available for the TO-92 case.
The heat sinks are either slip-on of clip-on heat sinks,
and are some what large compared to the size of the TO-92 body.
The size of the heat sink has a lot to do with the TO-92's plastic body.
The generic dimensions of the TO-92 package include the following:
Body width; 4.58mm +0.25, -0.15mm. Body height; 4.58mm +/-0.20mm.
Lead length 14.47mm +/-0.40mm. Lead width 0.46mm +/-0.10mm.
Lead spacing; 1.27 +/- 0.20mm, 1.02mm from the flat face of the component.
Commercial part numbers using a TO-92 package; BC556, BC557, BC558, BC559, BC560, BC171. A TL431 shunt regulator in a TO-92 .
No MIL spec parts use the TO-92 Transistor because of the plastic package.
No derating curve is listed for a transistor in a TO-92 package.
As a general rule military specifications will define metal or ceramic parts and components.
Note that the leads may come straight or ordered [purchased] formed or bent as shown in the BC171 picture to the left.
Many common parts use this package, including; 2N3904, MPS2222, 2N4401 and MPF102 transistors. Note that the 2N2222 is known as the MPS2222A, or PN2222 in this package [among other names].
Editor note; Any time a commercial part number is provided as a device using a particular package, that part number is just an example. As the same part [perhaps with a slightly different part number] may also be available in a completely different package. For instance the generic part, 2N2222, may also be purchased as a SOT-23 [as MMBT2222A] or SOT-223 [as PZT2222] package.
TO-92 Plastic Body TL-431