The NFC Forum has formally adopted a wireless charging specification that enables a single antenna in an NFC-enabled device to manage both communications and charging.
The Wireless Charging Specification (WLC) makes it possible to wirelessly charge small, battery-powered consumer and IoT devices with a smartphone or other NFC charging device at a power transfer rate of up to one watt.
“This solution makes it easier and more convenient to charge low-power IoT devices such as smart watches, fitness trackers, wireless earbuds, digital pens and other consumer devices,” the Forum says.
“NFC wireless charging is truly transformative because it changes the way we design and interact with small, battery-powered devices as the elimination of plugs and cords enables the creation of smaller, hermetically sealed devices,” chairman of the NFC Forum Koichi Tagawa explains.
A Bluetooth headset which includes NFC technology for pairing could also use the NFC interface for wireless charging, for example. In this case, the NFC antenna is used to exchange the pairing information and to transfer power.
The spec “uses the 13.56MHz base frequency and leverages the NFC communication link to control the power transfer,” the Forum adds.
“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 1,000 milliwatts.”
Published as a candidate specification last year, the specification has now been fully adopted and is “ready for implementation in the market”.