40 V N-channel in a 5x6 PQFN — the power-stage workhorse
The IRFH7446TRPBF is an Infineon N-channel MOSFET from the HEXFET and StrongIRFET series, rated for 40 V drain-source and 85 A continuous drain current at a 25 °C case temperature.
The 3.3 mOhm Rds(on) at 50 A and 10 V Vgs is the figure that sets the I²R conduction loss. At 50 A that is about 8.25 W of dissipation just from the channel, before switching losses are added. The 98 nC total gate charge at 10 V tells the BOM-cost engineer what gate-drive current is needed: at 100 kHz switching, the average gate current is 9.8 mA, well within a standard driver, but the peak current capability of the driver must still source that charge in the desired transition time. The 78 W maximum power dissipation at the case temperature is the thermal budget for the combined conduction and switching losses.
Temperature range and application environments
The 40 V drain-source rating provides headroom on 12 V and 24 V industrial and automotive buses, absorbing load-dump transients without avalanche breakdown.