Key differences between NFC and Qi charging

The most popular wireless charging standard currently in use is the Wireless Power Consortium’s (WPC) Qi charging standard. People consider Qi and NFC charging as competitive technologies, but many experts consider them in many ways as complementary wireless charging technology rather than competitive technologies, depending on the used applications. Here are some comparisons between Qi and NFC charging:

Qi charging, specified by the wireless power consortium, is strictly a power standard designed for wireless power transfer, while the NFC standard was mainly developed as the industry standard for data transfer. The Qi charging is working at the frequency of 110 to 205 kHz. With these low frequencies, Qi relies on tight coupling, and thus, Qi delivers up to 15 W (which is specified for mobile devices) or up to 2.000 W for larger enterprise devices.

NFC wireless charging standard is specified by the NFC Forum and it operates at the frequency band of 13,56 MHz. Due to higher frequency, it no longer relies on tight coupling, which means we also allow more loose coupling as it is in use in payment applications. The main outcome is much smaller NFC antenna sizes and, thus, more freedom of antenna placement in the application.

A further big advantage of NFC wireless charging is a much higher data rate, up to 848 kb/s, compared to Qi charging with only 2 kb/s. One of the biggest differentiators are the coil sizes, so NFC can be used here if you require a small antenna form factor.

Due to all previously mentioned factors, the design of the WLC system is cheaper where only an additional NFC chip needs to be needed. In Conclusion, NFC charging is preferable for small IoT devices which already use an NFC antenna (13.56 MHz) for communication &?data transfer and Qi charging is going to stay the main technology for only charging functionality at bigger enterprise devices that consume more power, anything with batteries 3.000 mAh and more.

Finally, it shall be mentioned that NFC-based wireless charging at 13.56 MHz and Qi- Charging are the only approved technologies and spectrum users for wireless charging in China. Other frequencies, like 6.78 MHz, are no longer allowed.