What the 35 ns reverse recovery time means for your switching supply
The STTH1202D is a 200 V, 12 A fast recovery diode from STMicroelectronics, built for the output stage of switching power supplies and PFC boost converters where the 35 ns trr cuts reverse-recovery losses. That 35 ns number is the key spec — it keeps the diode from hammering the MOSFET during hard-switching transitions, which directly affects efficiency and thermal rise in the rectifier stage.
12 A continuous rating — sizing the power path
Rated for 12 A average rectified current with a forward voltage drop of 1.1 V at that current, the STTH1202D handles main rectification in a 200 V DC rail or secondary-side rectification in telecom bricks.
TO-220-2 package — heatsink mounting and assembly
The through-hole TO-220-2 package (supplier device package TO-220AC) is the standard power tab for bolting to a heatsink. The junction is rated to 175 °C max, so the thermal design needs a good interface — the tab carries the heat, and the mounting hole takes a screw or clip. No MSL concern with through-hole, but store the reels dry if the pouch seal is broken.
No last-time-buy math needed for new designs — this one will be around for the foreseeable future.