Dual 40 A Schottky in a TO-247 — the low-Vf workhorse
The STMicroelectronics STPS80L30CY is a dual common-cathode Schottky rectifier rated for 40 A average per diode with a 30 V reverse voltage. Its forward voltage sits at 480 mV when carrying the full 40 A per diode, which keeps conduction losses manageable in high-current rectification and OR-ing stages. The fast recovery characteristic — ≤500 ns — qualifies it for switching frequencies above 200 mA where a standard diode would drag.
At 40 A per diode the forward drop is 480 mV, so each diode dissipates roughly 19 W at full rated current. In a TO-247-3 through-hole package with the MAX247 body, the junction-to-case thermal path needs a heatsink rated for that dissipation — the 150°C max junction temperature leaves a hard ceiling. The common-cathode configuration means both anodes share the same cathode tab, which simplifies the heatsink isolation: the tab is at cathode potential.
ST lists the STPS80L30CY as obsolete. That means no further factory orders — the only channel is surplus, broker, or last-time-buy inventory still in the distribution pipe. No official successor part is recorded, so a pin-compatible drop-in replacement would need to be qualified from the same TO-247-3 dual-Schottky family.