24V, 38A N-channel in a through-hole I-PAK
The on-resistance maxes out at 13.5mOhm with a 10V gate drive, and the gate charge is a modest 24nC, so the gate driver doesn't need to push much current for fast switching. The part comes in a TO-251-3 (I-PAK) through-hole package with short leads, which is hand-solderable and fits standard 2.54mm pitch prototyping grids.
Obsolete — plan for a replacement now
STMicroelectronics lists the STD38NH02L-1 as Obsolete. For new designs or to fill a BOM line, you will need to source from independent distribution or find a pin-compatible substitute. The key specs to match when selecting a replacement are the 24V Vdss, 38A continuous drain current, 13.5mOhm max Rds(on) at 10V, and the I-PAK (TO-251) through-hole footprint.
The 24V drain-to-source voltage rating suits low-voltage DC rails — 12V automotive, 24V industrial buses, or battery-powered systems where the bus never exceeds 20V. The 38A continuous drain current is the package-limited maximum at 25°C case temperature; real-world current handling depends on heatsinking and ambient temperature. The 13.5mOhm on-resistance at 10V gate drive means conduction losses stay under 0.5W at 6A, which is fine for a TO-251 package without a heatsink at moderate currents. Gate charge of 24nC at 10V keeps switching losses low in a 100kHz SMPS or motor-drive PWM stage.