The STTH2003CG is a fast-recovery epitaxial diode from STMicroelectronics, configured as a common-cathode dual diode in a D2PAK surface-mount package.
Obsolete — the sourcing reality
STMicroelectronics lists the STTH2003CG as obsolete. That means no further factory orders are accepted; the only channel is surplus inventory or broker stock. No official successor is listed, so a pin-compatible drop-in replacement would need to be qualified from a parametric cross-reference search.
10 A per diode, 300 V — the power-handling envelope
Each of the two diodes in the common-cathode pair is rated for 10 A average rectified current (Io) and 300 V DC reverse voltage (Vr). Reverse leakage is 20 µA at 300 V, a figure that doubles with temperature but stays manageable in most offline designs.
D2PAK surface-mount — the board-level fit
The TO-263-3 (D2PAK) package has two leads and a tab; the tab is both the thermal pad and the common-cathode connection. The mounting type is surface mount, so the tab gets reflow-soldered to a copper island on the PCB. No through-hole option exists — this part is strictly for reflow assembly. The tube shipping medium means the parts arrive in a rigid anti-static tube, not on a reel; plan for hand-loading or tube feeders if the pick-and-place supports it.