750 mV forward drop at 200 mA — the conduction loss floor
The BAT48 is a small-signal Schottky rectifier from STMicroelectronics, rated 40 V reverse and 350 mA average forward current. Its forward voltage drop is specified at 750 mV maximum when carrying 200 mA. The Schottky technology gives it a fast recovery time under 500 ns above 200 mA, which matters when the diode switches at moderate frequency in a buck converter catch diode or a flyback clamp.
DO-35 axial — legacy footprint, still in production
The BAT48 comes in the DO-35 axial-lead through-hole package. Junction temperature range is -65°C to 125°C, which covers industrial and automotive cabin environments. The 20 pF capacitance at 0 V reverse bias keeps switching losses low in high-impedance signal paths.