40 V, 3 A Schottky in a low-profile SMA Flat Leads package
The STPS340AFN is a 40 V, 3 A Schottky rectifier from STMicroelectronics, built for low forward voltage drop and fast switching in a compact surface-mount package. Its 630 mV maximum forward drop at 3 A keeps conduction losses manageable in a 3 A rail, while the fast recovery time — ≤500 ns above 200 mA — suits it for moderate-speed rectification and freewheeling in DC-DC converters and output OR-ing stages.
Ratings that size the thermal and electrical budget
The 40 V reverse voltage (Vr max) gives about 20 % headroom on a 24 V rail or 30 % on a 12 V rail — adequate for most low-voltage power supplies, but tight for 48 V bus applications. Reverse leakage is specified at 20 µA at 40 V — a typical Schottky figure that rises exponentially with temperature.
For new designs or BOM sustainment, the closest functional peer is the standard STPS340 series in the SMA Flat Leads package — the base product number STPS340 covers the same die in other package variants.