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TMS3705: RFID Chip Choices for ISO FDX-B

Pete Sampson
Prodigy 55 points
Part Number: TMS3705

I’m looking for a RFID chip or module that will read 11784/11785 tags at that are 134.2 kHz ISO FDX-B. The unit will be battery powered so it will need to be low powered and sleep between attempting to read a tag.

1) The TMS3705A chip would work but I believe it is obsolete, is there a newer part in production that would work?

2) The TMS3705EDRQ1 might work, what are the differences between the TMS3705EDRQ1 and the TMS3705A or are they drop in replacements?

3) Is the SOP-16 footprint the same as the SOIC-16 footprint?

Thanks,

Peter

  • 0
    TI__Mastermind 18265 points

    Hi Peter,

    the TMS3705 does not support FDX only HDX. Support for the FDX protocol is not available from TI.

    Best Regards,

    Helfried

  • 0 in reply to Helfried Vollbrecht
    Prodigy 55 points

    Thanks for your comment I didn't know that. My understanding is from online research is that "Both HDX and FDX follow the ISO standard and can be read by the same EID readers". I assume that if the TMS3705  can support half duplex it will be able to read to tag, just not write to it. Can you confirm that the TMS3705 should be able to read a FDX tag such as this one? Thanks!

    https://www.biomark.com/wp-content/uploads/2021/06/MERCK-Product-HPT8-3.pdf

  • 0 in reply to Pete Sampson
    TI__Mastermind 18265 points

    Hi Peter,

    I understand that this is a bit confusing. The ISO11785 standard has a definition for both, FDX and HDX. This is a different communication method and the tags follow either the FDX or the HDX part of the standard. This is independent of reading or writing a tag. At the reader side it is possible to support both but TI is focused on the HDX part. 

    For HDX the carrier is switched on for a defined time and loads a capacitor in the tag. The tag uses this stored energy to transmit back a FSK (frequency shift keying) modulated signal. For FDX the carrier is constant on and the tag transmits back by a load modulation of the carrier signal. Because this is completely different the TMS3705 can not support FDX tags even for reading of a tag.

    Best Regards,

    Helfried