The IRF6616TRPBF is an Infineon HEXFET N-channel MOSFET rated for 40 V drain-source breakdown and 19 A switching current, with a maximum on-resistance of 5 mOhm at Vgs = 10 V and Id = 19 A. That Rds(on) figure is the key efficiency spec for a 40 V FET — it sets the conduction loss floor in a synchronous buck, OR-ing diode replacement, or load switch. Gate charge is 44 nC max at 4.5 V, which keeps the driver current manageable at moderate switching frequencies.
Junction temperature and thermal budget
Power dissipation is rated at 2.8 W, so the board copper and airflow need to keep the junction below that 150°C limit under full load.
Gate drive and switching considerations
Vgs absolute maximum is ±20 V, which gives margin for gate-drive overshoot in a 12 V or 10 V gate-drive system. The 44 nC gate charge at 4.5 V means a 1 A gate driver can switch the FET in about 44 ns — fast enough for a 100–200 kHz converter without excessive cross-conduction. The threshold voltage is 2.25 V max at 250 µA, so the FET is fully enhanced with a 5 V logic-level gate drive, but a 10 V drive is recommended to hit the rated Rds(on).
