450 V / 4 A NPN in a full-pack TO-220
This is a common choice for offline flyback converters, switched-mode power supply primary-side drivers, and line-voltage motor-drive clamp circuits where the heatsink is at chassis ground.
The 450 V Vceo gives roughly 20% derating headroom off a 310 VDC rectified 220 VAC bus, which is standard practice for reliable offline operation. The 4 A Ic rating is continuous — repetitive peak currents in a flyback primary can exceed this, but the 30 W power limit will constrain the duty cycle and switching frequency before the current limit does. The Vce(sat) of 1.5 V at 2 A is a typical Darlington-like figure for this transistor class; it means conduction losses around 3 W at 2 A, so the heatsink must be sized for that dissipation at the 150°C maximum junction temperature.
It is ROHS3 compliant.
Package and mounting note
The TO-220FP full-pack variant uses a through-hole mounting style with three leads. The plastic body fully encapsulates the die, so the metal tab is electrically isolated — no mica washer or sil-pad required.