35 ns trr — the switching edge this part exists to deliver
The STTH1506TPI is an ultrafast high-voltage rectifier from STMicroelectronics, built as a pair of diodes in series inside a single TOP-3I through-hole package. That 35 ns trr places it squarely in the ultrafast class for 600 V boost diodes, PFC stages, and output rectification in switch-mode power supplies where the recovery tail of a standard fast diode would cost efficiency or blow the thermal budget. The series connection inside one package simplifies layout for voltage-doubler or center-tapped topologies — two diodes, one placement, one heatsink interface.
3.6 V forward drop at 15 A — plan the heatsink
Forward voltage is 3.6 V maximum at 15 A per diode. That is a conduction loss of 54 W per diode at full rated current, so the TOP-3I insulated tab needs a proper heatsink and thermal interface — the junction limit is 150 °C. The insulated tab is a real advantage here: no insulating washer needed, which cuts thermal resistance and assembly steps. If your design runs the diodes at a fraction of the 15 A rating, Vf drops, but always size the heatsink for the worst-case junction temperature at your operating point.
ST lists the STTH1506TPI as an active product.