1.25 Ohm Rds(on) — conduction loss at the operating point
The STW6N95K5: At 25 °C junction, 1.25 Ohm yields about 11 W conduction loss at 3 A — well within the 90 W power dissipation limit. The actual Rds(on) rises with junction temperature; at 150 °C it roughly doubles, so the thermal design should budget for that increase.
13 nC gate charge — fast switching without a heavy driver
The low Qg also reduces the gate drive power loss and allows faster rise/fall times, which helps keep switching losses in check.