P-channel power switch for 12 V / 24 V rails
The STD30PF03L-1 is a P-Channel MOSFET from STMicroelectronics' STripFET™ II generation, built for low-side load switching and reverse-battery protection in 12 V and 24 V systems. Its 30 V drain-to-source rating gives headroom on a nominal 12 V bus, and the 28 mΩ maximum on-resistance at 12 A gate drive of 10 V keeps conduction losses manageable for loads up to 24 A continuous at 25°C case temperature.
28 mΩ Rds(on) — what the drive voltage tells you
The headline 28 mΩ is specified at Vgs = 10 V, but the part is also characterised at 5 V drive. The gate charge is 28 nC at 5 V, which is light enough for a simple gate-driver or a microcontroller GPIO with a series resistor. Input capacitance is 1670 pF at 25 V Vds, so switching losses at moderate frequencies are acceptable; above that, a lower-Qg device would be worth evaluating.
STMicroelectronics lists the STD30PF03L-1 as Obsolete. For production builds, this part is available only through the surplus and independent-distribution channel — sealed reels with consistent date codes are the norm from factory-excess lots.
Package and thermal: I-PAK through-hole
The I-PAK (TO-251-3) is a through-hole package with short leads, smaller than the DPAK but still wave-solderable. The supplier device package is I-PAK, and the case style is TO-251-3. For continuous 24 A at 25°C case, a heatsink is mandatory; at elevated ambient, derate aggressively. The 175°C junction rating gives margin for short-duration overloads, but the junction-to-case thermal resistance is not listed in this data set — expect to measure or simulate for your layout.