An app note(PDF) from Freescale Semiconductor on wireless charging coil designs
There are many battery-powered devices, which need to be periodically charged, such as mobile phones, tablets, and battery-powered hand tools. These tools are usually charged by a dedicated cord from a USB port or from a dedicated wall adapter.
Wirelessly transferred power simplifies the charging of these devices and brings more convenience to the everyday lives of our customers. Dedicated controllers are required for wireless charging application control.
Freescale provides the WCT1xxx family of the dedicated controllers for the wireless charging applications. Each type is intended for a certain range of applications in the automotive or industrial and consumer area. Freescale provides the dedicated wireless charging software library intended for these controllers. This library maintains all functions required by the Qi specification.