To control secondary-side MOSFETs, synchronously-rectified flyback converters require electrically-isolated gate drive transformers. The construction of Wurth Electronics' WE-GDTI series in an EP7 package offers basic insulation for operating voltage of 250 V_RMS compliant with EN 61558-2-16. It allows a test voltage of 2500 V_DC between the primary and secondary windings. The μVs product in this series is 70% higher than that in the previous WE-GDT series. The EP7 core acts as a screen against external magnetic fields, at the same time reducing its own magnetic field. These transformers are supplied with three windings and with up to five different winding ratios.