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TRF7964A: Supply voltage query of TRF7964A

Part Number: TRF7964A

Hello,

I want to use RFID reader IC : TRF7964A  on 3.3V battery supply. Do I need to use Booster of 3.3V to 5V for Vin (Pin no. 2) pin. Or will it work fine if I provide 3.3V on Vin (Pin no.2 ). Vin supply voltage range according to datasheet is 2.7V to 5.5V but in absolute rating it is suggested to use 5 as a typical voltage.

Kindly suggest best suitable option.

  • Hello Margisha,

    The device can run just fine at 3.3V. Further reading of the datasheet would have unveiled we have a 5V mode and 3V mode set by Register 0x00 Bit 0. When supplying 3.3V, you should set the device to operate at 3V mode.

    Note that 5V is recommended because you get more output power and thus more read range from it (100mW@3.3V vs 200mW@3.3V), but plenty of applications use 3.3V when maximizing read range isn't the highest priority.
  • Hello Ralph,

    Thank you for your response. It is really helpful for me.

    Can you Tell me approximated read range at 100mW power and 200mW  so I can select best suitable for my application.

  • Hello Margisha,

    That is application specific and depends on a number of factors outside of our device specifications including the antenna dimensions for the reader antenna, the antenna matching network to connect to the 50 ohm point of our recommended TRF79xxA matching network, the tag technology (or technologies used), the commands used, the tag or target device antenna dimensions (primarily how well they will couple with the reader antenna), as well as possible environmental factors such as the presence of metal near either antenna.

    A general rule of thumb is that a well tuned system with good sized antennas and proper tuning will get around ~3-4cm with 3V operation and ~5-6cm with 5V operation. But you can get more range than that depending on your setup and tag technology.
  • Hello Ralph,

    Thanks for your kind response.

    I have gone through this PDF 'Antenna Design Guide for the TRF79xxA (Rev. B)' for Antenna design reference and guidance. 

    It is mentioned in the document that for better range larger antenna should be used, but at same point if antenna is very large TRF79xxA can not drive it properly.

    For our application there are not any size constraint. So can you kindly suggest any ideal antenna size which are commonly used for better range?

    Thanks and Regards,

    Margisha Dave.

  • Hello Margisha,

    That all depends what size tags will be used, but if you are expecting a broad array of tags then an antenna a bit smaller than credit-card sized would likely provide the best results. If you anticipate small tags are used, you would want a smaller antenna. It all comes down to the best inductive coupling between reader and tag coils.

  • Hello Ralph,

    Thank you so much. From this it is pretty clear about antenna dimensions.

    I am understanding that,

    As this IC supports ISO15693 protocol, it will support multi tag detection up to 4 cards at a time.

    Kindly correct me if I am wrong for this understanding. 

    Thanks and Regards,

    Margisha Dave.

  • Hello Margisha,

    Yes it will, we have example firmware which handles ISO15693 anticollision: http://www.ti.com/lit/zip/sloc297

    A basic description of the example firmware is provided here: https://e2e.ti.com/support/wireless_connectivity/nfc_rfid/f/667/t/493678

  • Hello Ralph,

    Is it possible to achieve read range of ~12 Cm any how with this reader IC?

    Our requirement is to read RFID TAG from the range up to 12 to 14 Cm so is it possible with this chip or with any other similar chips?

    Kindly suggest the method for this if any.

  • Hello Margisha,

    Yes that is possible if using ISO15693 technology.
  • Hello Ralph,

    Thanks for your response.

    Yes This IC TRF7964A supports the ISO15693 protocol so according to you this Chip can provide me range up to 12 CM.?

    Kindly elaborate the method to achieve this range with same IC if possible.

    Thanks & Regards,

    Margisha Dave.

  • Hello Margisha,

    Use decent sized antennas for both tag and reader (around credit-card sized) and tune antenna for Q of 18-20 as guided in SLOA241 I linked above.

    You will have to do the lion's effort, we offer collateral to explain the steps but that's where our ability to help stops as getting 12cm is an application specific requirement.