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TRF7960A full output power at manual 5V system

Other Parts Discussed in Thread: TRF7960A, TRF7960

I need TRF7960a to work on full output power at 5V, there are external CMU and TRF7960A on my board, also there are 3.3V for external CMU and 5V power supply for TRF7960A, internal power VDD_X(3.4V) of TRF7960A only supplies  VDD_IO of TRF7960A. CMU controls TRF7960A via SPI bus, there is not good signal level match between CMU IO(3.3V) and TRF7960 IO(3.4V); additionally 2 registers for Manual 5V system is wrote as below:

1. Chip Status Control Register (0x00): B4=0; B0=1;

2. Regulator and I/O Control Register (0x0B): B7=0; B2=1;B1=1;B0=1.

Can it work well based on above hardware and register set?

Thanks.

  • Hello,

    There seems to be no issue with all you've described. The level matching is no real issue - both MCU and TRF79xxA should have plenty of tolerance to handle a 0.1V difference. We commonly use a similar setup to let the TRF760A run at 5V.

    Are you asking for confirmation, or because an issue has been observed?
  • Thanks Ralph.

    I am debugging my HW board with TRF7960A, it can work on full output power at 3V with PCB antenna on board or external big loop antenna, but it can not read tags well when I want to let it work on full output power at 5V based on HW and registers set that I described above. What issue on HW or SW it can be from your experience?

    Best Regards

    Brian

  • Hi Brian,

    Do you have caps on Vddx?

    Are ASK/OOK and MOD pulled down?

    What is the state of your EN and EN2 lines?

    Ideally, can you share the schematic for the TRF7960A? We can look for any possible issues if so and can minimize HW issues this way.

    Software wise, what Regulator Control and Chis Status Control settings are you using?

  • Hi Ralph,
    I added capacitors on VDDX, but did not have effect. ASK/OOK and MOD are not pulled down, so is also ref design. EN is controlled by MCU I/O, EN2 connected to Ground.
    Chip Status Control Register (0x00): set 0x01;
    Regulator and I/O Control Register (0x0B): set 0x07.
    Can I have your e-mail for sending HW figure?
    its work on 5V full output power is unstable, sometimes there are modulation wave and can read tag, but for most time TX_OUT outputs pure 13.56 M sin wave without modulation.
    Thanks.
    Best Regards,
    Brian
  • Hi Brian,

    We recommend pull down resistors on ASK/OOK and MOD to avoid possible injection of noise into the system that can be caused by leaving them floating. May not be the cause of this issue, but strongly recommended regardless.

    EN/EN2 connections are good, are the caps you added to VDDX 0.01uF and 2.2uF?

    The register settings are okay, for configuration, and I assume since you said you can read a tag that you turn Chip Status Register (0x00) to 0x21 for read? Are you working off of any TI example firmware base? If so which one? Also which technology tag are you trying to read?

    I am going to send you an E2E friend request so you can send me a private message with your schematic. You can add it as an attachment to a private message using the Insert File option (looks like a paperclip a la email attachments).

  • Thank Ralph, I have sent message to you, please have a check.
    Best Regards,
    Brian