The STMicroelectronics STPS3L60UF is a 60 V, 3 A Schottky rectifier in the low-profile SMB Flat Leads package. It is designed for output rectification, freewheeling, and polarity protection in switch-mode power supplies and DC-DC converters. The 60 V reverse voltage gives comfortable margin on a 48 V bus or a 24 V industrial rail with transients. The 3 A average current rating covers most point-of-load and auxiliary supply outputs up to about 36 W at 12 V.
Forward drop and thermal budget
Forward voltage is specified at 620 mV maximum at 3 A. That is a low drop for a 60 V Schottky in this current class, which directly reduces conduction loss and keeps the junction cooler at full load. Just remember that reverse leakage climbs with temperature; at 150°C junction the 150 µA at 60 V (25°C figure) will be higher, so budget standby loss accordingly.
The DO-221AA / SMB Flat Leads package is a surface-mount, low-profile variant of the standard SMB. It uses the same 5.3 mm x 3.5 mm footprint as a conventional SMB but with flat leads that reduce height and improve solder-joint inspection visibility. No special thermal pad or via array needed — the SMB footprint with standard copper land pattern handles the 3 A continuous current if the PCB copper is adequate.