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Original question:

TMS3705: expected RF range

TMS3705: What is the longest possible reading distance range?

Mahdi Gholizadeh
Prodigy 20 points
Part Number: TMS3705
Other Parts Discussed in Thread: UCC27424, UCC27624

Tool/software:

Hello,

I am designing an RFID reader for FDX and 134 kHz tags using the TMS3705. To achieve a longer reading distance, I have included an amplifier between the TMS3705 and the antenna to increase the power of the signal sent to the tags. The matching capacitance has been tuned perfectly with the antenna. However, despite these efforts, I am unable to achieve the desired reading distance of 15 cm. The maximum reading distance I’ve been able to obtain is 10 cm, even after making various adjustments to the design and layout. I have attached some part of the schematic.

I have several questions regarding the TMS3705 and its design optimizations:

  1. What is the realistic range we can expect with the TMS3705 when targeting the “long-range” performance specified in the datasheet? Are there specific component-level adjustments needed to achieve this?

  2. What would be a reasonable expected range for our design setup?

  • 0
    TI__Expert 5275 points

    Hello Mahdi, 

    1. The maximum distance for the TMS3705 device is between 15cm - 25cm. The maximum end of this range is achievable by using the UCC27424 device in conjunction with the TMS3705. Please reference these two threads for more information: LF RFID, TM3705 + UCC27424 Max Range? and TMS3705 Distance of read a tag. Additionally, the maximum distance will depend on the type of RFID tag you are using. 

    2. I do not see the schematic attached. 

    Please let me know if you have any other questions or if there is any other confusion. 

    Thanks, 

    Isaac

  • 0 in reply to Isaac Larson
    Prodigy 20 points

    Hello Isaac,

    Thank you for your response. It’s reassuring to know that the maximum distance exceeds 15 cm. Apologies for forgetting to attach the schematic earlier; I’ve included it now. As shown in the schematic, I’m using the UCC27624 to extend the distance. The tag I’m using performs well with another design, achieving up to 20 cm, so I believe the tag itself is not causing the issue.

    1. Are there any layout tips I should consider to further optimize the design?

    2. I’m experiencing a similar issue with reading distance when using a 125 kHz IC. Do you know of an alternative IC that I could use in my design to improve performance?

    Thank you,

    Mahdi

  • 0 in reply to Mahdi Gholizadeh
    TI__Expert 5275 points

    Hello Mahdi, 

    For the 125kHz IC (htrc11001t on schematic), please open a new thread and the appropriate team will be able to help you. 

    Additionally, what kind of antenna are you using? Loop and Ferrite stick antennas are recommending and used with an inductance of 100uH - 500uH. 

    I do not see anything wrong with the schematic, but I will need to consult with the hardware team for a closer look. 

    Thanks, 
    Isaac

  • 0 in reply to Isaac Larson
    Prodigy 20 points

    Hello Isaac,

    I use loop antennas in my application, and the inductances of antennas are between 200 uH to 300 uH.

    Thank you,

    Mahdi

  • 0 in reply to Mahdi Gholizadeh
    TI__Expert 5275 points

    Mahdi, 

    Understood. I am still consulting with the team. 

    Additionally, my responses may be delayed, as I am out for business travel. 

    I will provide a response by the end of this week (01/10). 

    Thanks, 

    Isaac