Low profile coupled inductor substrate with fast transient response

The alloy flake composite magnetic material has been justified to be compatible with the conventional PCB manufacturing process. By embedding the layerwise core into multilayer PCB, a single-phase 3D integrated POL module achieves 700W/in³ power density and more than 85% efficiency. More important, the application of standard PCB process reduces the cost for manufacturing such integrated modules due to the easy automation and low temperature process. This paper tries to extend the same technology to multiphase POL module with coupled inductor. Combining the advanced control strategy, the high density and cost-effective two-phase POL modules are demonstrated for laptop VR application. The old low profile coupled inductor structure is modified slightly to improve its transient response. The air slots are added to reduce the transient inductance and enhance the coupling at light load condition. The non-linear inductance of the coupled inductor can be well controlled by using different slot structures. With the proposed coupled inductor structure, both low profile design and fast transient speed can be realized simultaneously.