Hello,
I have a nucleo-nfc06a1 board that I would like to use for wireless charging and communications to a st25dvi2c tag.
On the tag side, I have a rectifier bridge that supplies a battery charger. The resonant frequency of the tag antenna has been set to 15MHz and has an inductance of 1uH, as was suggested by STMicro.
On the reader side, I am able to swap the impedance matching network components for ones that will provide maximum power. I can use a VNA to ensure that the system impedance is resonant at 13.56 MHz for a given impedance. I can snap off and solder on another coil with higher Q and higher inductance if needed. The registers on the ST25r3916 have been set according to the st25r3916 disco board register readout for NFC-V configuration.
In the past I have tried the following:
-Setting the internal regulator to 5V (as opposed to the auto-regulator setting)
-Replacing the coil with a 200 Q, 3uH antenna (5cm in diameter)
-Setting the impedance matching network to be resonant at values ranging from 3 ohm to 15 ohm
I have been unable to see the ilim bit set to 1, which means that despite my efforts the output current is below 350mA. In addition, if the output power is 1.7W, I would expect possibly 20% efficiency (0.36W received) at a distance of a few millimeters (both antennas have a size of about 4cm in diameter). Instead, I see only 0.08W at the reciever.
My question is: what alterations, setting, and commands must be done to the NFC06A1 board such that output power is 1.7W. This is a spec that is found on its datasheet: "Up to 1.7 W output power with differential antenna" so one would expect this functionality without physical changes to the impedance matching network.
Thanks in advance!
Best,
Oliver
