Micro DC/DC converter that integrates planar inductor on power IC

A 1 W class step-down micro-DC/DC converter that integrates a (4 mm/spl times/4 mm) planar inductor on a (4 mm/spl times/5 mm) power IC has been fabricated. The converter operation was stable at 3 MHz switching, achieving a power density of 5.6 W/cm/sup 3/ and a converter efficiency of approximately 80%.