The STPS20SM120SFP is a 120 V, 20 A Schottky rectifier from STMicroelectronics, housed in a TO-220FP full-pack package. The full-pack (fully isolated tab) simplifies heatsinking — no insulating washer needed, and the metal tab is electrically isolated, which matters when multiple devices share a heatsink or the chassis is grounded.
ST lists the STPS20SM120SFP as Obsolete. For a BOM line that calls this exact part, procurement must go to the independent distribution channel. If your design is still in the pre-production phase, a pin-compatible or functionally equivalent replacement should be evaluated to avoid future supply gaps.
At the full 20 A forward current, the maximum forward voltage (Vf) is 890 mV. That is a typical figure for a 120 V Schottky at this current — not the lowest-dropout option, but the 120 V rating trades a slightly higher Vf for better reverse-blocking capability. Reverse leakage at the rated 120 V is 210 µA, which is modest for a 20 A Schottky; expect leakage to rise significantly at the 150 °C maximum junction temperature, so derate the reverse voltage in high-temperature environments or use a heatsink sized to keep the junction below 125 °C.