NFC PN532

[briansune]

Dear NXP,

I am Brian and would like help some guidelines on coexist between wireless power and NFC.

I have observed via oscilloscope and when WPT is running the NFC RX or TX or a snooping probe can see a strong modulation on the 13.56MHz OOK signal.

If I am planning to add a high pass filter, should it injected to which location?

1) Before damping resistor after antenna coil

2) between matching and EMC filter

3) RX path (no idea which is the best point)

Thank you

[Tomas_Parizek · Accepted solution]

Hello Brian, 

What "wireless power" are you using? It is Qi Charging? At which frequency? 

Typically there is no need to add any High pass filter since the Qi charger works at a different frequency than NFC. Also, these two systems should not work at the same time -> First NFC (typically check if there is some card in the proximity), If no, then WPT starts.

In case you see some interference from the WPT source, you have to check the PN532 Rx Gain and if needed decrease it. 

BR

Tomas