The STD40P8F6AG is an STMicroelectronics automotive-grade P-channel power MOSFET in a TO-252 (DPak) surface-mount package.
The 40 A continuous rating at Tc=25°C is the package-limited current at the case; real-world derating depends on PCB copper area under the DPak tab and ambient airflow. Input capacitance Ciss of 4112 pF at 25 V drain-source is moderate; the switching losses at 20 kHz will be dominated by the gate-drive current available, not by the Miller plateau duration.
No official successor or replacement part has been issued — the base product number STD40 covers the family, and this specific AEC-Q101 variant is the automotive-grade offering.
TO-252 DPak — footprint and thermal management
The TO-252-3 (DPak) package has two leads plus a large tab that forms the drain connection. The supplier device package is D-PAK (TO-252).