Wireless charging circuit

RE: Wireless charging circuit

Quark — Mon, 02 Jul 2018 15:40:04 GMT

Great help! Thanks!

RE: Wireless charging circuit

Dajgoro Labinac — Mon, 02 Jul 2018 14:25:28 GMT

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

RE: Wireless charging circuit

Quark — Mon, 02 Jul 2018 14:10:33 GMT

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

RE: Wireless charging circuit

Dajgoro Labinac — Mon, 02 Jul 2018 11:40:54 GMT

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.

RE: Wireless charging circuit

Quark — Mon, 02 Jul 2018 05:28:38 GMT

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.

RE: Wireless charging circuit

Hung Bui — Tue, 21 Mar 2017 13:35:44 GMT

I actually don't know much about NFC, but I would assume then you will have trouble receiving NFC signal.

RE: Wireless charging circuit

Dajgoro Labinac — Tue, 21 Mar 2017 11:51:57 GMT

Ok, so its two separate antennas, my only worry is if there is a scenario in which the induced currents damage the nRF52 NFC front end. Or could I maybe mediate the problem by adding protection diodes to the NFC antenna coil?

RE: Wireless charging circuit

Hung Bui — Tue, 21 Mar 2017 11:47:37 GMT

You may need to consider the frequency of the wireless charging, which technology it uses inductive or resonant. There could be interference between the NFC antenna and the wireless charging antenna. We would suggest to avoid placing them close to each other. And definitely you can't combine the 2 antenna together , at least on our chip.