2N3055 Temperature-Power Derating Curve
NPN Power Transistor. Package, TO-3 Metal Can.
2N3055 Applications; General-purpose switching and Amplifiers.
2N3055 Transistor Operational Power Derating Curve
Derate the power dissipation for the 2N3055 by 0.657 W/0C for any operating temperature above 250C. No power reduction is required for temperatures below 25C
Use the curve to determine the amount of power [wattage] derating based on case temperature [operational ambient temperature]. Because the collector is connected to the case the device may be directly attached to a heat sink to allow higher temperature operation. Extrusion heat-sinks are by far the most common for power amplifiers, and allow the formation of elaborate two-dimensional shapes capable of dissipating large heat loads. Refer below for a graphic of one style of heat sink. The two styles of heat sinks for a 2N3055 include Rectangular Shape, or Diamond Shape.
Note that the curves indicate Case Temperature [Tc] and applies to free-air [still-air]. Fans may be used to induce forced air cooling which will greatly enhance operation over higher temperatures. In any case for longest life use either of the gray curves.
Sockets are available for a TO-3 package, but should only be used during design and testing. Example socket; 0804MC [8-pin TO-3 socket].
Temperature derating is a standard practice for engineers during circuit design. Use any of the three lower curves in the graph above, or select a line parallel to one of the curves. The highest curve to the right represents the maximum operating temperature of the 2N3055 and should not be used in the design [but as a guide].
Refer to MIL-PRF-19500/407E; Semiconductor Device, Transistor, NPN, Silicon, Power, Types: 2N3055, JAN, JANTX, and JANTXV, [TO-3 package]. Also seen as a TO-204AA case.
2N3055 Maximum Operational Ratings:
Collector Emitter Voltage = 70 volts dc [Vceo]
Collector Base Voltage = 100 volts dc [Vcbo]
Emitter Base Voltage = 10 volts dc [Vebo]
Collector Current = 15 Amps dc [Ic]
Base Current = 7 Amps dc [Ic]
Power Dissipation 250C = 6 Watt [Pt]
Operating Temperature, Junction = -65 to +2000C [Tj]
Storage Temperature = -65 to +2000C [Tstg]
TO-3 Pin Out: Lead 1 = emitter, lead 2 = base, lead 3 = collector.
The collector is electrically connected to the case.
The Lead-Free [Pb-Free] version is 2N3055G in a TO-204AA metal package. [RoHS]
Refer to; MIL-PRF-19500; Semiconductor Devices, General Specification
Derating Definitions
Case mount. A type of package (outline) which provides a method of readily attaching one surface of the semiconductor device to a heat dissipater to achieve thermal management of the case temperature. |
 TO-3 Heat Sink |
Case temperature. Case temperature is that temperature measured at a specified point on the case of a 2N3055 semiconductor device. The 2N3055 is a two-terminal device, the collector forms the case of the device. Some data sheets or derating curves may use the case temperature of a 2N3055 while other data sheets may use the junction temperature of the 2N3055.
Ambient temperature. Ambient temperature is the air temperature measured below a semiconductor device,
in an environment of substantially uniform temperature, cooled only by natural air convection [Free-Air], and not materially
affected by reflective and radiant surfaces. The derating equation and curve imply that no near-by device is radiating heat toward the 2N3055, and that the device is not installed with an enclosure that inhibits air flow.
Also not stated, the Power Dissipation curve works at sea-level, a higher altitude may required tighter derating.
