Antenna Power Setting for PN7150

[Ganesh_G]

Hi Team,

We are using the PN7150 IC for detecting RFID cards and running it on a Linux kernel 5.4 (AM335x) with the /drivers/misc/nxp-pn5xx driver.

The datasheet specifies a maximum current of 30mA, but our measurements show approximately 7mA of current to the antenna.

We would like to know how we can retrieve and modify the antenna power settings from the firmware (driver) side.

Below is the antenna structure:

• Type: Loop – Copper trace
• Geometry (inches): 1.57 × 1.57 (4 turns)
• Frequency Range: 13.56 MHz

Regards,
Ganesh.

[EduardoZamora]

Hello @Ganesh_G

Hope you are doing well.

Please, consider that our support for PN7150 is very limited as it is Not Recommended for New Designs; we recommend using PN7160 instead.

Tx power may depend on the antenna characteristics and a proper matching circuit. Please make sure you have followed the PN7150 Hardware Design Guide; Chapter 7 describes the Antenna interface. Also, you can refer to the NFC Antenna Design training, an online training series that could help you with key aspects for the antenna, optimizing and debugging, and testing to get the best-matched antenna for your product; this in addition to the NFC Antenna Tool. Additionally, I will recommend you checking the Chapter 6 Power interface of PN7150 Hardware Design Guide.

More information on transmitter voltage configuration can be found in PN7150 User Manual, Section 5.7.

Regards,
Eduardo.