40 V, 120 A N-channel — what the TO-220 carries
The STMicroelectronics STP200NF04 is a STripFET™ II N-channel power MOSFET in a through-hole TO-220-3 package. The 310 W power dissipation ceiling at the case and 175°C maximum junction temperature place it in the high-current, high-temperature switching class — think motor drives, battery isolators, DC-DC converters in industrial or automotive auxiliary loads where the ambient can push past 85°C.
At 90 A the on-resistance sits at 3.7 mOhm maximum with 10 V gate drive. That is roughly 30 W conduction loss at full current — the 310 W package dissipation rating gives headroom, but only with a serious heatsink and good thermal interface. The gate charge of 210 nC at 10 V means the driver needs to source about 2.1 A peak to switch in the 100 ns range; a weak gate-drive IC will stretch the switching edges and push losses into the linear region. Input capacitance of 5100 pF at 25 V Vds is moderate for a 120 A FET — the Miller plateau is manageable with a standard totem-pole driver.
Obsolete — channel reality for the STP200NF04
175°C junction — where it runs
The 175°C ceiling is 25°C higher than the common 150°C max — that extra margin matters in sealed enclosures, engine-bay compartments, or any spot where the ambient hits 105°C and the self-heating from 120 A pulses stacks on top. The threshold voltage of 4 V maximum at 250 µA drain current is standard for a 10 V gate-drive part; at lower gate voltages the Rds(on) climbs steeply, so do not try to drive this FET from a 3.3 V logic signal without a level shifter.