250 V, 17 A switching load ceiling
The STD17NF25 is an N-channel power MOSFET from STMicroelectronics' STripFET™ II series, rated for 250 V drain-source breakdown and 17 A continuous drain current at 25°C case temperature. This puts it in the medium-voltage, moderate-current class — suitable for switching loads in offline power supplies, DC-DC converters, and motor pre-drive stages where the bus rail sits at 48 V to 150 V and the peak current stays under the 17 A ceiling.
Conduction loss and gate drive budget
Maximum on-resistance is 165 mOhm at 8.5 A drain current with a 10 V gate drive. At 17 A the Rds(on) will be higher due to self-heating — the 90 W power dissipation limit at the case is the thermal budget that governs the real-world current derating. The 29.5 nC total gate charge at 10 V means the gate driver must supply roughly 2.95 mA per 100 kHz of switching frequency just to charge the gate capacitance; the 1000 pF input capacitance at 25 V drain-source adds to the switching loss calculation.
DPAK thermal and mounting
Housed in the DPAK (TO-252) surface-mount package with an exposed drain tab. The tab must be soldered to a copper pad on the PCB — the thermal resistance to ambient depends on the board's copper area and layer count. The -55°C to 150°C junction temperature range covers industrial ambient and under-hood automotive environments, but the 150°C upper limit means the thermal design must keep the junction below that at full load.