The STMicroelectronics STP12IE90F4 is an NPN emitter-switched bipolar transistor from the ESBT® series, rated at 900V and 12A continuous. It comes in a through-hole TO-220-4 Full Pack package (fully isolated tab) and is intended for gate driver applications — typically driving the primary-side switch in high-voltage power converters, induction heating, or welding inverters where the emitter-switched topology offers a combination of low saturation voltage and fast switching.
STP12IE90F4 carries an Obsolete lifecycle status. There is no factory lead time to manage, but the available inventory is finite and declining.
The 900V collector-emitter voltage rating suits this device for off-line AC-DC converters operating from rectified 230VAC or 277VAC mains with adequate derating for switching transients. The 12A continuous current rating supports output power levels in the several-hundred-watt range when used in a typical flyback or half-bridge topology.