2026-05-27 8:44 AM - last edited on 2026-05-28 12:12 AM by Andrew Neil
antenna tuning section
pinout is correct or not
capacitor section
@Dilip
im facing issue for developing A SMART RFID reader using ST25R3912-AQWT this chip
as per the application circuit it was mentioned RFO1 AND RFO2 are trasmitter pins but what about the TO1 AND TO2 pins can you guide me for this
also keeping components inside the antenna is permitted or should i avoid it...?
Solved! Go to Solution.
2026-05-27 10:19 PM
Hello AKHIL_GEORGE,
the antenna tuning section is dependent on the antenna and the desired matching impedance.
It cannot be generalized. Its values should be based on AN4974. The topology is fine.
The AGD pin requires a decoupling of 1uF // 10nF.
Having electronics inside the antenna coil causes losses (performance reduction) and the possibility to couple the 13.56MHz into the PCB traces, which can cause noise in the receiver (sensitivity loss) or EMI issues (coupling of the 13.56MHz signal into the supply lines). There should be sufficient spacing between the traces, components, planes inside the antenna and the antenna itself.
The TO pins are TEST OUTPUT pins and not functional required. They can be used to output internal signals for debugging in case of issue.
BR Travis
2026-05-27 9:51 PM
@Travis Palmer hai can you please help me this
2026-05-27 10:19 PM
Hello AKHIL_GEORGE,
the antenna tuning section is dependent on the antenna and the desired matching impedance.
It cannot be generalized. Its values should be based on AN4974. The topology is fine.
The AGD pin requires a decoupling of 1uF // 10nF.
Having electronics inside the antenna coil causes losses (performance reduction) and the possibility to couple the 13.56MHz into the PCB traces, which can cause noise in the receiver (sensitivity loss) or EMI issues (coupling of the 13.56MHz signal into the supply lines). There should be sufficient spacing between the traces, components, planes inside the antenna and the antenna itself.
The TO pins are TEST OUTPUT pins and not functional required. They can be used to output internal signals for debugging in case of issue.
BR Travis
2026-05-27 11:08 PM
thank you very much Travis for the quick review and reply really appreciable
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