Rectifier ratings and the circuit-fit decision
The 1N645UR-1/TR is a standard recovery silicon rectifier rated for 225 V reverse voltage (Vr) and 400 mA average rectified forward current (Io). The 1 V forward drop at 400 mA is the conduction loss floor at rated current — at lower forward currents the Vf drops, but the 1 V figure is the one to budget for worst-case thermal rise in a 400 mA rail. The standard recovery speed (>500 ns, >200 mA Io) places this diode in line-frequency rectification duty — 50/60 Hz mains, DC bus precharge, or freewheeling in low-speed inductive loads. At switching frequencies above a few kilohertz the reverse recovery time dominates the switching loss; a fast-recovery or Schottky part would be the better fit there. Reverse leakage is specified at 50 nA maximum at 225 V — a low leakage figure that matters for high-impedance divider networks, sample-and-hold front-ends, or battery-powered circuits where the diode's own draw must stay below the microamp range.
Package and reflow integration
Housed in the DO-213AA (SOD-80) surface-mount package, the 1N645UR-1/TR mates with the standard SOD-80 footprint — a two-pad layout with the cathode band marking the polarity. The metal end-cap construction handles standard reflow profiles; the junction operates from -65°C to 175°C, covering military-temperature-range requirements for avionics, downhole instrumentation, or outdoor telecom enclosures. Supplied on Tape & Reel (TR), this is the production-friendly format for pick-and-place assembly. The reel quantity is the standard DO-213AA carrier tape pitch — confirm the feeder setup for the SOD-80 body length before the line runs.
It remains a current-production part suitable for both new designs and ongoing BOM replenishment.