What this dual diode does in your power stage
The STTH16R04CG-TR is a 400 V, 8 A per diode fast-recovery rectifier array from STMicroelectronics, with the two diodes sharing a common cathode in a single D2PAK package. The 1.5 V forward drop at 8 A is typical for a 400 V-class ultrafast diode; it's a trade-off you accept for the speed. The junction temperature range goes to 175 °C, so it can sit next to a hot heatsink in a cramped PSU chassis without derating into early failure.
50 ns trr — what that buys you on the switching node
A 50 ns reverse recovery time reduces the reverse-recovery spike in the MOSFET, lowering EMI and allowing a smaller snubber.
Package and mounting — D2PAK hand-solder reality
The D2PAK (TO-263) is a surface-mount package with a large exposed tab on the bottom. That tab is the common cathode connection and the primary heat path. For a hobbyist or repair bench, you can hand-solder it with a decent iron and some flux — the tab needs a good thermal pad on the PCB or a blob of solder to the copper pour. The 10 µA reverse leakage at 400 V is low enough that you won't see standby losses in a lightly loaded supply.
No NRND or EOL notice is published.