2N6770 FET [TO-204AE package, Modified TO-3]. Hermetic MOSFET
IRF450: 500V Single N-Channel Hi-Rel MOSFET in a TO-204AA package
2N6770 Maximum Drain Current vs Temperature
The graph indicates that the 2N6770 may draw 12 amps at 25 degrees centigrade. However at any temperature above 25 degrees the drain current must be reduce to sustain the same case temperature.
2N6770 Maximum DC Ratings
Voltage Gate to Source = 20 volts dc
Voltage Drain to Source = 500 volts dc
Voltage Drain to Gate = 500 volts dc
Junction Temperature = -55 to +150oC
Note that in addition to the derating curve being the same, the electrical specifications are also the same between the 2N6770 and 2N6770-T1. Only the package is different, designated by the T1 suffix.
MIL-PRF-19500/543; Semiconductor Device, Transistor, Field Effect, N-Channel, Silicon, Repetitive Avalanche Types 2N6764, 2N6764T1, 2N6766, 2N6766T1, 2N6768, 2N6768T1, 2N6770 [TO-254AA], and 2N6770T1 [TO-204AE]
TO-204 Flange mount. A type of package [diamond base in this case] which provides a method of readily attaching one surface of the semiconductor device to a heat sink to achieve thermal management of the case temperature. The Drain is electrically connected to the case. While the Source and Gate pins are located as shown [for a FET].
TO-254 Tab mount. A type of package which provides a method of readily attaching one surface [Tab] of the semiconductor device to a heat dissipater [Heat Sink] to achieve thermal management of the case temperature. All terminals are isolated from case in a TO-254 package. When securing the tab to a heat sink the body of the TO-254 may lift off the surface of the board, use epoxy to secure the body of the TO-254 to the circuit board.
Compensating for temperature rise and Component Derating by Current Compensation and thermal design considerations.