Rectifier fit for low-power AC-to-DC conversion
The B4S-E3/80: The Vishay B4S-/80 is a single-phase bridge rectifier in the TO-269AA (MBS) surface-mount package, rated for 400 V peak reverse voltage and 500 mA average rectified current.
The 400 V peak reverse rating covers 120 VAC and 240 VAC mains with margin — after derating for line transients, the 400 V PIV keeps the junction safe. Reverse leakage is 5 µA at 400 V and 25°C — negligible for a standby supply, but leakage doubles roughly every 10°C junction rise, so at 125°C it approaches 320 µA. That matters for a bias supply that idles at high ambient; the leakage current adds to the output ripple and raises the no-load dissipation.