The BSS138N E7854: The Infineon BSS138N is a small-signal N-channel MOSFET from the SIPMOS® family, built for low-current load switching, level translation, and general-purpose switching up to 60 V drain-source. Operating temperature spans -55 to 150 °C junction, so it works in industrial and automotive-adjacent environments (though not AEC-Q qualified per the listing).
Infineon has ended production, so new-issue procurement runs through the independent surplus and broker channel.
Key ratings — the so-what for your design
The 60 V drain-source breakdown gives headroom for 12 V, 24 V, and even 48 V rails in low-power subsystems. The 230 mA continuous rating is the thermal ceiling in the SOT-23 package at 360 mW dissipation — derate above room temperature. Gate threshold is specified at 1.4 V max with 250 µA drain current, which means a 3.3 V logic signal can turn it on fully, though the 4.5 V and 10 V drive-voltage columns in the Rds(on) spec suggest best performance with a 5 V or higher gate drive. Gate charge is only 1.4 nC at 10 V, so switching losses stay low even at moderate frequencies — useful for a PWM fan or solenoid driver. Input capacitance of 41 pF at 25 V drain-source confirms it's a small-signal device, not a power switch.