The STTH8003CY is a 300 V, 40 A per diode fast-recovery rectifier from STMicroelectronics, configured as a common-cathode pair in a single TO-247-3 package. Its 60 ns reverse recovery time (trr) places it in the class of ultrafast diodes suited for continuous-conduction-mode PFC boost stages, output rectification in high-frequency SMPS, and motor-drive freewheeling clamps where stored charge recovery loss dominates the switching transition.
Common-cathode pair in a TO-247 — layout and thermal fit
The common-cathode configuration shares the same tab potential for both diodes, simplifying heatsink isolation in a single-sided cooling scheme. The TO-247-3 through-hole package needs a proper pad pattern for the large lead cross-section; the MAX247 supplier device package designation indicates the standard JEDEC outline. At 40 A per diode, forward voltage drops to 1.25 V at rated current, so total dissipation can reach 50 W per pair — a forced-air or large-fin heatsink is mandatory for continuous operation. The 80 µA reverse leakage at 300 V is a static loss contributor that matters at high junction temperature, where leakage roughly doubles every 10°C above 100°C.
Obsolete — sourcing reality and cross-reference options
The STTH8003CY is marked obsolete in STMicroelectronics' product status. The Q Automotive series designation suggests the original qualification target was automotive-grade applications, but the obsolete status means any replacement should also carry an AEC-Q101 or similar automotive approval if the end equipment requires it.