2.6 mOhm Rds(on) — the conduction loss floor
Infineon BSZ0902NSATMA1 N-channel OptiMOS MOSFET: 30 V Vdss, 2.6 mOhm Rds(on) at 20 A, 10 V. The dual current rating — 19 A at 25°C ambient (Ta) and 40 A at case temperature (Tc) — tells you the thermal limit depends heavily on the board layout: the 19 A figure assumes no heatsink beyond the PCB copper, while the 40 A figure requires a heatsink on the package's exposed pad.
The package is an 8-lead PowerTDFN (PG-TSDSON-8-FL), a surface-mount footprint with an exposed drain pad.
Design-in checklist: drive voltage, capacitance, and footprint
Input capacitance is 1700 pF at 15 V Vds. Gate charge is 26 nC at 10 V. Maximum Vgs is ±20 V. Power dissipation is 2.1 W at ambient and 48 W at case temperature.
