PCB integrated inductors for low power DC/DC converter

This paper discusses the use of PCB integrated inductors for low power DC/DC buck converters. Coreless, magnetic plates and closed core structures are compared in terms of achievable inductance, power handling and efficiency in a footprint of 10 x 10 mm(2). Analytic and FEM methods are applied and typical current waveforms encountered in a buck converter are included. The magnetic layers consist of electroplated NiFe, so that the process is fully compatible with standard PCB process. A 4.7 muH PCB integrated inductor with DC current handling of up to 500 mA is presented. This inductor is employed in a 1.5 W buck converter using a commercial available IC. The footprint of the entire converter measures 10 x 10 mm(2) and is built on top of the integrated inductor to demonstrate the concept of integrated passives in power electronic circuits to achieve ultra flat and compact converter design.