120 V, 70 A N-channel — the conduction-loss story
The Infineon IPD70N12S311ATMA1 is a 120 V, 70 A N-channel MOSFET from the OptiMOS™ series, built for automotive power switching where every milliohm of on-resistance matters. AEC-Q101 qualification and the -55°C to 175°C junction temperature range mean this part is qualified for under-hood and engine-bay environments where standard industrial MOSFETs would derate or fail. The TO-252-3 (DPak) surface-mount package keeps the board footprint small, but the exposed tab demands a proper thermal pad on the PCB to pull heat out.
Gate charge and switching — what 65 nC buys you
With a typical gate charge of 65 nC at 10 V, this MOSFET is not a high-speed switcher for 500 kHz+ converters — it is sized for PWM frequencies in the 20 kHz to 100 kHz range where the switching loss from charging and discharging the 4355 pF input capacitance is manageable. The 10 V drive voltage for minimum Rds(on) is standard for automotive gate drivers; a 5 V logic-level drive will not fully enhance the channel, so budget a proper gate driver IC or a 10 V rail.
Package reality — TO-252-3 on the board
The PG-TO252-3 (DPak) package is a single-gauge surface-mount tabbed device. The tab is the drain — it needs a generous copper pour on the PCB to handle the 125 W power dissipation at the case. The ±20 V max gate-source voltage means the gate is not fragile, but ESD handling is still required — a wrist strap and grounded workstation are the minimum.