Wireless charging circuit

[Dajgoro Labinac]

Hi

What would be the best way to interface a wireless charging circuit with a nRF52 device? I've found a IC from Texas instruments that does the job, but is it safe to have the charging receiving coil around the NFC antenna of the nRF52? Would the induced currents from the wireless charger cause issues to the nRF52? Also, if not, is there a way to use the same antenna for charging with the dedicated charging chip and have it still function as the nRF52 NFC antenna so a single antenna coil can be used instead of two separate ones. Antennas have to be packed together due to device size.

[Quark]

Hi Dojgoro, I hope this find you well. I am currently doing a similar product development with NFC + Qi. I was wondering how you product is now. Did you find a solution and solve the problem. If possible, would you share your experience? My design is that NFC and Qi will not both work at the same time. Whenever wireless charging is detected, nrf52 must be deactivate and NFC only works when not charging. Thanks in advance.

[Dajgoro Labinac]

Hi.
Actually yes, I found a solution that works, and its rather straightforward.
All you need to do is add a 1nF capacitor in series with the NFC antenna (after the 300pF caps) and that will prevent low frequency qi currents from overloading the IC, while the NFC will remain unaffected. 

[Quark]

Hi, Dojgoro,
Thanks for sharing the information. Did you use a single coil for both NFC and wireless charge? 

[Dajgoro Labinac]

I made my own flex pcb design antenna. It is two coils one next to eachother.
You can buy them from ebay:
www.ebay.com/.../112754238510

[Quark]

Great help! Thanks!