Series B78416 interface transformers are designed for DSL equipment. Whereas ferrite material was the driving force behind the industry switch from EP13 to EP7 cores, this design is the result of optimized core technology. Compared with an EP7-based transformer, the new transformer with the EP5XL core is 25 percent smaller in area (64.5 mm²), 31 percent lower in height (7 mm), and 48 percent smaller in volume (451.5 m³).Direct comparison of type B78416A1850A003 (EP5XL) with its predecessor B78417A1764A003 (EP7) demonstrates that, despite its smaller core volume, the new transformer has the same longitudinal balance and total harmonic distortion values while satisfying the leakage inductance requirements. Only its ohmic resistance is higher. The tiny transformer can even satisfy the requirements for surge voltage strength and is designed for 2.5 kV/2/10 µsec. The higher ohmic resistances can be compensated by next-generation line card chips.