Investigation of passive component size in VRMs

The performance of three different VRM circuit topologies is presented to compare the size of magnetic components involved. It is shown that the smallest solution is produced using a synchronous buck; with interleaved circuits having similar size. transformer circuits are shown to have the greatest potential for miniaturisation, but current planar magnetic technologies are limited in terms of winding utilisation area. Practical component designs are presented for comparison of the buck, interleaved and push-pull forward converters.