The LL1572, LL1573, LL1589 are pulse transformer designed for digital audio. They are designed with a rather large amorphous metal core and have thus low copper resistance, high signal tolerance and low internal capacitance. The amorphous core has a very high mu. Thus, when used, the transformer should be protected from DC current.
LL1572 isolation transformer specifications
Turns ratio: 1:1 Dims: (Length x Width x Height above PCB (mm)) 15 x 9 x 11 Spacing between pins 1 and 2: 10.16 mm (0.4") Spacing between pins 1 and 3: 5.08 mm (0.2") Rec. PCB hole diameter: 1.5 mm Weight: 2 grams