60 V small-signal N-channel MOSFET in SOT-23 — the gate-drive trap to watch
The BSS138NH6327XTSA2: The part carries a max gate threshold of 1.4 V at 26 µA drain current, which means it turns on cleanly with 3.3 V logic — but the Rds(on) spec at 4.5 V drive is not guaranteed to match the 10 V figure, so a design using 3.3 V gate drive should budget for higher conduction loss.
Infineon lists the BSS138NH6327XTSA2 as an active product. For dual-sourcing, the BSS138 family includes multiple pin-compatible SOT-23 N-channel parts from various manufacturers — the key parametric match is the 60 V Vdss and sub-5 Ohm Rds(on) at 10 V.
Thermal and package constraints
Maximum power dissipation is 360 mW at 25 °C ambient in the SOT-23 package — a firm reminder that this is a small-signal device, not a power switch. Continuous drain current at higher ambient temperatures must be derated accordingly. The PG-SOT23 supplier package (Infineon's designation for the SOT-23-3) uses the standard footprint;.