Wireless Charging allows for wireless charging of small battery-powered devices like those found in many IoT devices, This approach can help avoid the need for a separate wireless charging unit for small devices if the device includes an NFC communication interface. For example, a Bluetooth headset which includes NFC technology for pairing could also use the NFC interface for wireless charging. In this case, the NFC antenna is used to exchange the pairing information and to transfer power.
This NFC specification uses the 13.56 MHz base frequency and leverages the NFC communication link to control the power transfer. NFC technology is unique in that it allows the transfer of power to an NFC tag to enable communication by providing a constant carrier signal. The WLC specification extends this communication functionality of NFC technology to enable wireless charging. The WLC specification ensures a safe charging process between two NFC-enabled devices in either static or negotiated modes. Static mode uses standard radio frequency (RF) field strength and provides a consistent power level. Negotiated mode uses a higher RF field supporting four power transfer classes of 250, 500, 750 and 1000 milliwatts.
Version 2.0 of the Wireless Charging technical specification defines a new antenna class next to the antenna class already defined by the WLC 1.0 specification. This new antenna class with a smaller antenna size allows the implementation of tiny IOT devices which can be charged by NFC technology.