The STTH1512D is a 1200 V, 15 A fast-recovery rectifier from STMicroelectronics, built for hard-switched topologies where reverse recovery time drives turn-off loss. Its 105 ns trr at 15 A keeps the switching node clean in continuous-conduction-mode PFC stages and high-voltage flyback converters. The 2.1 V forward drop at rated current is a trade-off for the speed — expect higher conduction loss than a standard 1200 V diode, but the recovery charge saved at high frequency more than compensates in most designs.
ST lists the STTH1512D as obsolete.
Package and mounting — TO-220AC through-hole
The STTH1512D comes in a TO-220-2 package (supplier device package TO-220AC), through-hole mount, shipped in tube. The junction is rated to 175 °C maximum, so the tab must be heatsunk in any continuous-current application near the 15 A rating. Off-state leakage is 15 µA at 1200 V — negligible at room temperature, but doubles roughly every 10 °C above 25 °C junction.