2N3485 Temperature-Power Derating Curve [2N3486]
PNP Silicon Switching Transistor. Package, TO-46 metal Can. [3-Leaded Through-Hole Device]
Maximum Rated Power vs Operational Ambient Temperature
Use the Graph to determine how much to derate power [wattage] based on the surrounding ambient temperature [Ta]. The chart indicates a thermal resistance junction to ambient of 325C/W. Transistor Derating Curves
Maximum operation power occurs at 250C, derate above that ambient temperature.
Temperature derating is a standard design practice for electronic engineers.
Refer to specification sheet MIL-PRF-19500/392; Semiconductor, Transistor, PNP,Silicon, Switching, Types 2N3485A and 2N3486A, JAN, JANTX, and JANTXV, [TO-46]. JAN; Joint Army/Navy.
2N3485 Maximum Ratings:
Collector Emitter Voltage = 60 volts dc [VCEO]
Collector Base Voltage = 60 volts dc [VCBO]
Emitter Base Voltage = 5 volts dc [VEBO]
Power Dissipation 250C = 500mW
2N3485 Operating Temperature = -65 to +2000C
Note at 2000C, maximum operational wattage is 0 watts
Manufacturers of Transistors and vendors, Manufacturers of Heat Sinks
The metal can of the 2N3485 does not provide much area to attach a heat sink. However the component leads may be used to conduct heat away from the device and into the printed circuit board. Keep the terminal leads as short as possible when used as a heat dissipator, a larger than needed copper pad will also help to dissipate the heat into the circuit board.
Lead 1 is Emitter, lead 2 is Base, and lead 3 is Collector [Graphic is left].
MIL-PRF-19500; Semiconductor Devices, General Specification
How to Derate; Guideline to Derating Electronic Components
