RE: NFC Antenna With DC Blocking Capacitors

Kyle — Tue, 05 Apr 2016 16:49:57 GMT

Thank you, Bjørn.

Upon further consideration, I also realized that blocking caps are unlikely to actually prevent reverse current flow. The NFC antenna is already an AC-coupled device, so blocking caps are redundant.

I'm assuming that a strong NFC field can generate sufficient AC voltage to forward bias the ESD diodes connected between the NFC pins and VDD inside of the nRF52 such that they begin to rectify the AC voltage and generate DC current flow back into the power supply.

RE: NFC Antenna With DC Blocking Capacitors

bjorn-spockeli — Tue, 05 Apr 2016 09:30:11 GMT

Adding two DC blocking capacitors between the NFC pins and the NFC antenna is not something that we recommend as this will most certainly affect the NFC functionality in a negative manner.

I recommend staying within the nRF52 Product Specification,i.e add a series diode between the battery and the device if the battery does not tolerate return current.

-Bjørn