What the D2PAK package means for your board
The STPS2545CG-TR: That tab is the common cathode for both diodes, so the PCB copper pour under the part doubles as a heat spreader and the output rail — keep the trace wide and use thermal vias to a ground plane if the average current per diode stays near 12.5 A. The 570 mV forward drop at 12.5 A per diode means conduction loss is about 7.1 W per diode at full rated current — the tab-to-ambient thermal path needs to be designed for that, not just the junction's 175°C ceiling.
12.5 A per diode — what that rating actually drives
Each of the two Schottky diodes in this common-cathode pair is rated for 12.5 A average rectified current — that's the DC output current per diode in a forward converter or the average current in each leg of a center-tap secondary. At 12.5 A the forward voltage is 570 mV typical — a Schottky's Vf is lower than a PN diode's at the same current, which keeps the rectification losses down in a 45 V output rail. The 45 V reverse voltage rating is the blocking voltage — it handles a 36 V nominal rail with margin for transients, but not a 48 V bus.
Fast recovery — why it matters here
In a 100 kHz switching supply the reverse recovery losses are negligible compared to a PN diode — that's the whole point of using a Schottky in the output stage.
ROHS3 compliant — no restricted substances above the threshold limits, and the part carries the full ST warranty.