What this N-channel TrenchMOS switch is for
The Nexperia PH3120L,115 is an N-channel TrenchMOS™ power MOSFET in a LFPAK56 (SOT-669) surface-mount package. The TrenchMOS process keeps gate charge to 48.5 nC at 4.5 V, giving a reasonable figure of merit for low-voltage, high-current switching.
Rds(on) at junction temperature — the number that matters
The datasheet lists 2.65 mOhm maximum at 25°C with 10 V gate drive and 25 A drain current. That number roughly doubles at 125°C junction, so the real conduction loss in a hot board — say a motor drive or a power supply inside a sealed enclosure — is closer to 5 mOhm. The drive voltage range (4.5 V to 10 V) means you can use a 5 V gate-drive rail, but the Rds(on) will be higher than the 10 V figure; budget accordingly. At 4.5 V gate drive the gate charge is 48.5 nC, which sets the switching loss in the driver: a 2 A gate driver charges it in about 24 ns.
The LFPAK56 (SOT-669) is a Power-SO8 footprint with an exposed drain pad on the bottom. Without that via stitch, the junction will exceed the 150°C limit well before 100 A continuous. Input capacitance is 4457 pF at 10 V drain, so the gate-drive loop inductance needs to be short to avoid ringing at the ±20 V gate-source maximum.