Gate drive and switching profile
The STWA40N95DK5: Gate threshold voltage is 5 V maximum at 100 µA drain current. Recommended drive voltage for minimum on-resistance is 10 V. Total gate charge is 100 nC at 10 V.
Temperature range and thermal design
The 450 W power dissipation at case temperature is a theoretical maximum with an ideal heatsink; real-world dissipation is limited by the thermal resistance of the TO-247 package and the heatsink interface. The long-lead variant adds clearance for high-voltage creepage on the PCB.