Power transformers are an integral part of an isolated DC-DC converter with a high voltage ratio. An essential requirement of such a transformer design is to achieve a low leakage inductance for power transfer. This paper proposes a transformer design using foil conductors with a half-turn high-current (HC) winding which has the following benefits: 1) less number of turns in both of the HC and low-current (LC) windings in comparison to a conventional design; 2) easy termination of the LC winding; 3) low leakage inductance by virtue of less number of turns and ease of interleaving of the LC and HC windings. The incorporation of half-turn HC windings provides openings through which the LC winding turns can pass. This allows the LC winding turns to be wrapped continuously, resulting in easy interleaving and termination. Analytical design followed by 3-D FEA results and bench top measurements on a hardware prototype are provided for a half-turn-winding transformer designed for a 12-288V, 3kW, 50kHz DC-DC converter.