Guidelines for FET Design
2N6768 FET [TO-204AE package, Modified TO-3]. Hermetic MOSFET
IRF350: 400V Single N-Channel Hi-Rel MOSFET in a TO-204AE package
Maximum Drain Current vs Case Temperature
The derating graph applies to a 2N6768 in either a TO-204AE or TO-254AA package. In either case the curve applies to the reduction in Drain current with increasing temperature. This particular derating graph covers case temperature, other data sheets may show Drain current vs ambient air temperature.
2N6768 Maximum DC Ratings
Voltage Gate to Source = 20 volts dc
Voltage Drain to Source = 400 volts dc
Voltage Drain to Gate = 400 volts dc
Junction Temperature = -55 to +150oC
MIL-PRF-19500/543; Silicon N-Channel, Repetitive Avalanche Field Effect Transistor, Types 2N6764, 2N6764T1, 2N6766, 2N6766T1, 2N6768, 2N6768T1,
2N6770, and 2N6770T1, JAN [TO-204AE; formerly TO-3].
The T1 designations use a different package style, but the same Semiconductor Device.
Related Field Effect Transistors: 2N6764 FET, 2N6766 FET, 2N6770 FET
TO-204 Case mount. [Flange Mount] A type of package which provides a method of readily attaching one surface of the semiconductor device to a heat dissipater [heat sink] to achieve thermal management of the case temperature. The Drain is electrically connected to the case. In this instance the package uses a completely metal diamond base shape.
Editor note: One noticeable aspect of derating Field Effect Transistors [FET] over temperature is that they don't follow the same decline as transistors. The power rating for transistors fall in a linear rate as the temperature increases. While the performance of FETs decline at a higher rate as the temperature increases.