The STTH15L06D is a 600 V, 15 A fast-recovery epitaxial diode from STMicroelectronics. Its 85 ns reverse recovery time (trr) lets the diode turn off cleanly in continuous-conduction-mode PFC stages. The 1.55 V forward drop at 15 A is a reasonable trade-off for the speed.
STMicroelectronics lists the STTH15L06D as Active. No last-time-buy notice is in effect. For new designs, this is a standard-shelf part with no near-term obsolescence risk.
