Active production — no BOM risk
Microchip Technology lists the 1N648-1 as Active.
500 V reverse, 400 mA average — low-current high-voltage rectifier
Rated 500 V DC reverse (Vr max) and 400 mA average rectified current (Io). This is a standard-recovery diode with a recovery time >500 ns, so it is not intended for high-frequency switching — it belongs in 50/60 Hz rectification, snubber clamps, or DC bias supplies where the reverse voltage is the load-bearing spec. Reverse leakage is 50 nA max at 500 V, which is low enough for high-impedance divider networks or sample-and-hold circuits where leakage current would shift the bias point.
-65°C to 175°C junction — military temperature grade
That is the full military/aerospace band (MIL-STD-883, Method 1010 Condition C). For a design that must operate in an engine bay, satellite thermal-vacuum chamber, or downhole tool, this diode continues conducting without derating across the entire temperature envelope.
DO-35 axial-lead — through-hole integration
Housed in a DO-204AH (DO-35) axial-lead package. Through-hole mounting suits legacy board layouts, point-to-point wiring, or high-reliability assemblies where solder-joint inspection is required.