The STPST3H100AF is a 100 V, 3 A Schottky rectifier from STMicroelectronics, housed in a SOD-128 flat package. The 175°C junction rating gives headroom in compact, surface-mount layouts that run hot.
At 3 A forward current, the maximum forward voltage is 755 mV — this sets the conduction loss floor. At 100 V reverse, the leakage current is 5.7 µA, a figure that rises with junction temperature. The 175°C Tj max allows the diode to run at higher ambient temperatures without derating, but the leakage increase at elevated Tj must be factored into the thermal budget. In a 3 A output rail, the Vf × If product is about 2.3 W at full load; the SOD-128 flat package's thermal resistance to the board copper determines whether that heat can be sunk without exceeding the junction limit.
Package and rework — SOD-128 flat profile
The SOD-128 flat package (also called SOD128Flat) is a surface-mount, leadless design with a low profile. The flat leads sit flush against the PCB pad, which helps with solder wetting and visual inspection after reflow. For rework, the package has low thermal mass — a hot-air station at 300–350°C with a fine nozzle lifts it cleanly without cooking adjacent parts.
For BOM planning, the active status means no near-term LTB risk, but the part should be qualified for new designs with the usual supply-chain monitoring.