800 V, 8 A single-phase bridge — what it means for the BOM
The KBU8K-E4/51: The Vishay KBU8K-/51 is a single-phase bridge rectifier in the standard KBU through-hole package, rated for 800 V peak reverse voltage (Vrrm) and 8 A average rectified output current (Io). The 800 V peak reverse rating covers nominal 480 VAC three-phase line-to-line rectification with margin for line transients — a 480 Vrms line peaks at 679 V, so this part stays inside its abs-max ceiling even with a 10 % overvoltage. The 8 A average current is specified at the package's thermal limit; in a 50 °C ambient with natural convection, derate to about 6 A continuous to keep the junction below 150 °C (the TJ max per the datasheet).
RoHS3 compliant, with no exemption conflicts for EU or UKCA markets. The standard KBU package is a mature, single-die SIP format that Vishay has produced for decades — no package-related obsolescence risk.
As a single-phase bridge, the KBU8K-/51 converts AC input (50/60 Hz) to a pulsed DC bus in linear supplies, battery chargers, and low-power motor drives. The 800 V rating also suits it for 277 VAC single-phase industrial control transformers. The through-hole KBU package (4-SIP, 0.100-inch pitch) mates with standard PCB layouts and can be heatsunk via the metal tab — the junction-to-case thermal path is the limiting factor for continuous current above 6 A.