What the 30 ns reverse recovery time means for your circuit
The 1N6536 is a standard fast recovery diode with a reverse recovery time (trr) of 30 ns, which places it in the class of diodes that switch off quickly enough for moderate-frequency rectification and snubbing without the higher forward drop of an ultrafast part. Rated for 400 V reverse voltage and 1 A average forward current, it handles the common 250 VAC or 400 VDC bus rectification in power supplies up to about 100 W output, with the 1.5 V forward drop at 1 A setting the conduction loss at roughly 1.5 W — a figure that calls for adequate lead length or a small heatsink in still air.
This means it is safe to specify into a new BOM without worrying about a forced redesign mid-production.
The through-hole axial package (A, Axial) is a standard DO-41 or similar outline — the body is cylindrical with wire leads on both ends, designed for hand insertion or wave soldering. The bulk packaging means parts are loose in a bag or tube, not taped for automated placement. Board layout is straightforward: drill 0.8 mm to 1.0 mm holes on a 0.4-inch lead spacing, route the anode and cathode traces to handle 1 A continuous plus inrush, and keep the diode close to the transformer or inductor it snubs to minimise loop inductance that would otherwise extend the effective recovery time.
Reverse leakage and thermal considerations
At the full 400 V reverse rating, the 1N6536 leaks 10 µA maximum — a negligible 4 mW of standby loss, but one that doubles roughly every 10 °C junction rise, so at 125 °C the leakage approaches 160 µA and the associated power loss climbs to 64 mW, still small but no longer negligible in a no-load standby budget. The 1.5 V forward drop at 1 A is typical for a 400 V fast recovery diode in this current class; a Schottky would drop half that but cannot block 400 V, and an ultrafast silicon-carbide diode would drop about the same but switch in under 10 ns. The 1N6536 sits in the middle — fast enough for 50-100 kHz switching without the cost premium of SiC.