Schottky rectifier for low-voltage, high-efficiency rectification
The ON Semiconductor 1N5820RL is a 20 V, 3 A Schottky barrier rectifier in a DO-201AD axial-lead package. Its forward voltage drop is 475 mV at the full 3 A forward current, which keeps conduction losses low in power-supply output rectification, freewheeling diodes, and polarity-protection circuits. The Schottky technology gives it a fast recovery characteristic — typically under 500 ns — so it handles switching frequencies above 200 mA without the reverse-recovery losses of a PN-junction diode.
The 20 V reverse voltage (Vr max) sets the rail voltage this diode can block. In a 12 V or 15 V bus, the 20 V rating leaves about 5 V of headroom — enough for most switching transients, but not for 24 V systems. The 3 A average rectified current (Io) is the DC load it can carry continuously. For a 2 A output supply this is comfortable; for a 3 A rail you are running at the absolute limit and should derate for ambient temperature rise. The junction temperature ceiling is 150°C, so the thermal path through the axial leads into the PCB or heatsink determines how much current you can actually pull.
No last-time-buy date or successor part is recorded in the official lifecycle data. That means the only available stock is new-old-stock or surplus inventory held by independent distributors.