The BU2508-E3/45: The BU2508-/45 is a Vishay single-phase bridge rectifier rated for 800 V peak reverse voltage and 3.5 A average rectified current — these are the numbers that decide whether it fits a bulk-capacitor charging or line-rectification stage in a power supply. The 1.05 V forward drop at 12.5 A pulsed current means conduction loss in the bridge is manageable for a 3.5 A continuous load, but the peak surge rating is what handles the inrush into a discharged capacitor bank at power-on. Reverse leakage is 5 µA at 600 V — low enough that the bridge does not contribute significant standby power in a lightly loaded offline supply.
Temperature grade and environment
The through-hole 4-SIP BU package (isoCINK+™ BU) is a standard SIP footprint — it sits upright on the PCB with the tab for heatsink attachment, which is the expected mounting for a bridge in a convection-cooled supply.