2N6306 Temperature-Power Derating Curve
NPN Power Transistor. Package, TO-3 Metal Can [TO-254AA, TO-257AA].
2N6306 applications; High voltage inverters, Switching regulators, Amplifiers

2N6306 Transistor Derating Curve
The above chart details the maximum allowable power dissipation with increasing case [Tc] temperature. Maximum operational power dissipation is achievable at 25C. However above 25C the maximum package dissipation, or power, must be reduce to insure that the devices junction temperature remains constant. However below 25C the 2N6306 does not require any derating, down to it's minimum operating temperature of -65C.
The higher the ambient temperature [or case temperature] is increased the lower the allowable power dissipation, as depicted in the curves. Decreasing a devices operational limits as temperature is increased is called derating, in this case derating a devices operational power dissipation vs increasing case [ambient] temperature. This particular graph depicts the derating of a 2N6306 transistor in a TO-3 package.
An alternate method of derating; linear derating factor average = 0.833 W/0C, above 25C.
Attach a heat sink to increase the device's operating temperature range. Or apply forced air cooling to dissipate the heat, the chart is for still air [no fan].
For longest life use the two bottom 'gray' lines. The top 'black' line represents maximum temperature, while the dashed line represents thermal break-down.
Refer to MIL-PRF-19500/498E; Semiconductor Device, Transistor, NPN, Silicon, Power, Types 2N6306, 2N6306T1, 2N6306T3, 2N6308, 2N6308T1, 2N6308T3, JAN, JANTX, and JANTXV [TO-3, TO-254AA, TO-257AA]
2N6306 Maximum Ratings:
Collector Emitter Voltage = 250 volts
Collector Base Voltage = 500 volts
Emitter Base Voltage = 8.0 volts
Power Dissipation 250C = 5 Watts
2N6306 Operating Temperature = -65 to +2000C
2N6306 Storage Temperature = -65 to +2000C
2N6308 Maximum Ratings:
Collector Emitter Voltage = 350 volts
Collector Base Voltage = 700 volts
Emitter Base Voltage = 8.0 volts
Power Dissipation 250C = 5 Watts
2N6308 Operating Temperature = -65 to +2000C
2N6308 Storage Temperature = -65 to +2000C
Case mount device. 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.
How to Derate; Guideline for Derating Electronic Components
Department of Defense Specifications:
MIL-PRF-19500: Semiconductor Devices, General Specification
MIL-STD-750: Test Methods for Semiconductor Devices









