2N5339 Transistor Derating Curves

2N5339 Temperature-Power Derating Curve
NPN Switching Silicon Transistor. Package, TO-39 Metal Can.
2N5339 Applications; General Purpose low power Amplifier, Switching Transistor

Air Temperature Derating Curve for 2N5339 Transistor

The graph shows the maximum DC power dissipation with increasing ambient temperature [Ta] for a 2N5339 in a TO-39 metal can. A derating curve for the 2N5339 in a TO-276 Surface Mount Package [SMD05] is not shown. Maximum operational power dissipation is achievable only at 25⁰C [Still-Air]. Above 25C the maximum package dissipation must be reduced to insure that the devices junction temperature remains constant. The higher the ambient temperature is increased the lower the allowable DC power dissipation, as depicted in the curves, or this equation; derate 5.71mW/⁰C above 25⁰C.

Decreasing a devices operational limits as temperature is increased is called derating, in this case derating a devices operational power dissipation vs increasing ambient temperature. Above room temperature the device must be derated by 4.6mW/⁰C. For reference a derating graph for case temperature is shown below.

Attaching a heat sink to the 2N5339 device will allow higher temperature operation with out the need to derate or reduce the power consumption [as much].

Implementing forced air into the design will also allow the 2N5339 transistor to operate at higher temperatures with higher power dissipation rates. The derating curve is for Free-Air and does not account for system operation with a fan. However, because the curve implies free-Air it also does not account for the device placed within an enclosure or chassis which inhibits air flow.

Refer to MIL-PRF-19500/560H; Semiconductor Device, Transistor, NPN, Silicon, Switching, Types 2N5339 [TO-39] AND 2N5339U3 [TO-276AA], JAN, JANTX, JANTXV, JANS, JANHC, AND JANKC.
Screening, processing and qualified per MIL-PRF-19500.

2N5339 Maximum Ratings:
Collector Emitter Voltage = 100 volts dc [Vceo]
Collector Base Voltage = 100 volts dc [Vcbo]
Emitter Base Voltage = 6.0 volts dc [Vebo]
Collector Current = 5.0 amps dc [Ic]
Base Current = 1.0 amp dc [Ib]
Power Dissipation 25⁰C = 1.0 watt
Gain = 60 minimum [hfe]
Operating Junction Temperature = -65 to +200⁰C [Tj]
Design Hint; Keep in mind the 2N5339 may not dissipate power at 200 degrees C
Storage Temperature = -65 to +200⁰C [Tstg]

TO-39 Case Derating Curves

2N5339 Derating Definitions
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. Also note that the 2N5339 curves apply to sea level.
Temperature coefficient. The ratio of the change in a parameter to the change in temperature.
Thermal resistance. Thermal resistance is the temperature rise, per unit power dissipation, of a junction above the temperature of a stated external reference point under conditions of thermal equilibrium.
This [off-site] link provides the Thermal Impedance of the 2N5339 Transistor; showing both a Junction-to-Case and Junction-to-Ambient thermal graph.
Storage temperature. [Tstg] is a temperature at which the device may be stored without any power being applied.