NFC for wireless charging

Overview
Use cases
Products
 

With the rising popularity and adoption of NFC technology, its application areas are expanding and reaching markets beyond payment, access control, and consumer electronics.

End users can now benefit from innovative applications thanks to NFC, such as device pairing, authentication, and parameter setting, thereby improving product user experience and convenience.Taking a new turn, NFC technology is now enabling wireless charging.

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Why use NFC for wireless charging?


Standardized by the NFC Forum, NFC wireless charging technology brings the advantage and convenience of not having to use physical plugs for charging devices.

Up to now, only technologies relying on big antenna dimensions with simple geometries enabled wireless charging in very few product segments in the consumer industry. These technical constraints limited the application areas of wireless charging technologies, which therefore could not be implemented in small devices with low power requirements, like earbuds and fitness trackers

ST’s NFC wireless charging solution allows device makers to overcome these challenges: by offering minimal requirements in terms of system size and the possibility to use flexible, bendable antenna PCBs, ST’s NFC solution can be used to power up small and battery-powered devices

Tiny dimensions

Flexible antenna design

Multiple NFC use cases


Cost efficient

Wireless charging with NFC can be enabled in existing products that already embed this technology, allowing device makers to streamline the electronic and mechanical design of existing products and save BOM costs. Device makers can simply configure their device settings and define NFC as the primary means to charge their device.

Wireless charging with NFC also brings about additional flexibility and convenience for end users, as it allows consumers to use their smartphone as a back up to charge other NFC-enabled, connected devices, such as wireless earbuds if they run low on power.

NFC charging: the tiniest solution for wireless charging

Discover how the ST25 NFC wireless charging solution can improve product design and user! experience.

 

Target applications


Wireless charging technologies have been around for several years. Many of them are proprietary, offer no interoperability, and target devices with high power requirements and therefore big antenna sizes and an extensive BOM.

Implemented in smartphones, tablets, and other bigger-sized products, the wireless charging technology based on the Qi standard is one of the most popular in the field. Antenna geometries with dimensions of 10 cm² and above allow power transfers up to 45 Watts.

With antenna dimensions of around one cm² and below, NFC wireless charging technology targets a different set of products. It offers easy integration while providing the right power level for small, battery-operated applications, such as earbuds, fitness trackers, and other wearables and IoT products.

Enabling NFC wireless charging with ST25 readers and tags


NFC wireless charging relies on a charging transmitter, also called a “Poller” in the NFC Forum specification, and a power receiver, also called a “Listener”. The Poller and Listener are an integral part of the NFC charging system to provide an optimized and efficient power transfer.

Compliant with the NFC Forum specification for wireless charging, ST’s ST25R NFC readers and ST25DV-I2C NFC tags enable the design of NFC wireless charging solutions. Integrated with additional ST components, such as an STM32 microcontroller, these ST25 readers and tags allow you to design a complete NFC wireless solution.

NFC Wireless charging in your charging device
 

The ST25R3916 NFC reader provides you with the right toolset and performance features to develop a wireless charger that transmits power.

NFC Wireless charging in your product to charge
 

The ST25DV-I2C dynamic tag can be used to implement the Listener and be integrated in end devices to receive power. The dynamic tag acts as data receiver and communication interface to the MCU on one side; on the other side it is responsible for sending charging control instructions to the poller (charging transmitter).