The STPS2150A is a Schottky rectifier rated for 2 A average rectified current and 150 V reverse voltage. At the full 2 A load the forward drop is 820 mV, producing about 1.64 W of conduction loss. That dissipation has to be sunk through the SMA package's copper pad area on the PCB — a standard footprint with a 15–20 mm² top-layer copper pour keeps the junction below the 175 °C maximum.
Reverse leakage at 150 V — the standby power trade-off
Reverse leakage is specified at 1.5 µA when the diode is blocking 150 V. That figure is typical at 25 °C junction; at elevated temperature leakage rises exponentially, so in a 85 °C ambient the leakage current can increase by a factor of 10–20×. For a low-power standby rail where the diode is reverse-biased most of the time, that leakage contribution to the quiescent budget is worth checking against the system's idle current target.