2N6676 Temperature-Power Derating Curve
NPN High Power Transistor. Package, TO-3 Flange Mount.
2N6676 Applications; High power switching, power amplifier
2N6676 Temperature Derating Curve, Case Temperature
The chart indicates the maximum power dissipation with operating case temperature for a 2N6676. 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. The higher the ambient temperature is increased the lower the allowable 2N6676 power dissipation, as depicted in the curves. Note that this curve relates to Case Temperature [Tc].
Derating is the method of decreasing a devices operational limits as temperature is increased, in this case derating a devices operational power dissipation vs increasing ambient temperature. This particular graph depicts the derating of a 2N6676 and 2N6678 transistor in a TO-3 package or TO-254 package. Attaching the TO-3 metal package to a heat sink will allow the device to operate at a higher temperature than depicted in the curve. The collector of the transistor is connected to the case. In the same fashion a heat sink may be attached to the TO-254 to allow a greater operational range. Heat sinks are available for both package styles.
The derating curve for the T3 package is slightly different than what's shown above. The two operational curves [gray above] begin at 65C and 75C and drop in a straight line down to 110C and 125C.
Refer to MIL-PRF-19500/538; Semiconductor Device, Transistor, NPN, Silicon, Power,
Types 2N6676 & 2N6678 [TO-3], 2N6676T1 & 2N6678T1 [TO-254], 2N6676T3 & 2N6678T3 [TO-257AA], 2N6691 & 2N6693 [TO-61]; qualified to JAN, JANTX, JANTXV, and JANS.
The T1 suffix define a TO-254 while the T3 suffix defines the TO-257 package.
2N6676 Maximum Operation Ratings:
Collector Emitter Voltage = 300 volts dc [Vce]
Emitter Base Voltage = 8.0 volts dc [Veb]
Collector Base Voltage = 300 volts dc [Vcb]
Power Dissipation = 175 Watts [Tc = 250C]
Power Dissipation = 6 Watts [Ta = 250C]
Operating Temperature = -65 to +2000C
Storage Temperature = -65 to +2000C
TO-3 Pinout note; Terminal 1 Emitter, Terminal 2 Base, Case Collector.
TO-61 Pinout note; Terminal 1 Emitter, Terminal 2 Base, Terminal 3 Collector.
TO-254 Pinout note; Terminal 1 Base, Terminal 2 Collector, Terminal 3 Emitter.
TO-257 Pinout note; Terminal 1 Base, Terminal 2 Collector, Terminal 3 Emitter.
The package out-line between the TO-254 and TO-257 is basically the same. However the physical dimensions are different, check the page dealing with the component package to determine the physical dimensions.
