The Infineon BAT54-04E6327 is a dual Schottky diode in a series configuration, housed in a PG-SOT23-3-3 package. It's rated for a maximum reverse voltage of 30 V and can handle an average forward current of 200 mA per diode.
The 30 V Vr(max) covers most common low-voltage rails with margin — 12 V, 5 V, 3.3 V — but don't use it on a 24 V bus if you expect transients. The 800 mV forward drop at 100 mA is typical for a small-signal Schottky; at lower currents the drop is lower, which helps in battery-operated designs where every millivolt matters.
Package and mounting — SOT-23-3 footprint
It's a surface-mount part in the standard SOT-23-3 footprint (also known as TO-236-3 or SC-59). The PG-SOT23-3-3 is Infineon's specific variant designation. No thermal pad to worry about — just the three leads. The junction temperature rating of 150°C gives reasonable headroom for ambient up to 85°C or so, as long as you stay within the current derating curve.
RoHS compliance is standard for Infineon's current SOT-23 portfolio, though the specific statement isn't in this listing; verify against the manufacturer's latest PCN or the part's own compliance document.