The GBU4J-E3/45: The GBU4J-/45 is a standard-recovery single-phase bridge rectifier from Vishay, rated for 600 V peak repetitive reverse voltage and 3 A average rectified output current. That 600 V rating gives you headroom on a 240 VAC mains line — the peak of a 240 V sine wave is about 340 V, so the 600 V PIV leaves margin for transients and line surges without avalanche stress. The forward voltage is specified at 1 V maximum when conducting 4 A — that is the conduction loss per diode pair. At 3 A average output, expect roughly 3 W of dissipation across the bridge, which the GBU package's copper leadframe can sink into the PCB or a small clip-on heatsink. Reverse leakage is just 5 µA at the full 600 V blocking voltage and 25 °C junction — low enough that it won't affect efficiency in a continuously running supply, but note that leakage doubles roughly every 10 °C rise, so at 125 °C junction it will be higher.
Temperature range and deployment context
A bridge rectifier in an outdoor telecom rectifier or an industrial power supply that sees 85°C ambient still has 65°C of margin before hitting the absolute maximum junction limit. The GBU package is a 4-pin single-in-line through-hole format with a standard 5.08 mm pitch. The copper tab on the package body is electrically live at the DC output potential — keep that in mind during layout if you plan to bolt a heatsink to it.
Lifecycle and compliance posture
Vishay lists the GBU4J-/45 as Active in production — no end-of-life notice, no last-time-buy window.