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TRF7962A: other choice for L1 & L2 inductors in matching circuit

Jo Chen
Intellectual 2895 points
Part Number: TRF7962A
Other Parts Discussed in Thread: TRF7970A

Hi team, 

My customer has been using TRF7962A for a long time, recently their supplier has shortage of L1 & L2 inductors so my customer would like to know how to choose a proper L1 & L2 to keep current performance (5 - 10mm communication range). Their current solution is SWI0603F-R33J & SWI0603F-R15J 

Do we have recommended part number for that? Thanks.

Jo

  • 0
    TI__Mastermind 18265 points

    Hello Jo,

    I don't have a direct recommendation for that coil that can be used as replacement.

    From an internet search I came to the Murata type LQW18ASR33J00D and LQW18ASR15J00D. What I see from the datasheet I think this could be a possible replacement.

    Best regards,

    Helfried

  • 0 in reply to Helfried Vollbrecht
    Prodigy 10 points

    Hello Helfried,

            Thank for your reply.

            Could you share me your experience about the impact by changing the L1/L2 characteristics.

            Such as : if we change the Q factor / DCR/ SRF of L1/L2, what itme of RFID will be changed? transmittion distance?

           

    Best Regards,

    CY  

       

  • 0 in reply to CY Chou
    TI__Mastermind 18265 points

    Hello,

    the two inductors are part of the matching network that will convert the 4 Ohm output impedance of the TRF7970A to the 50 Ohm impedance of the antenna.

    I am not a specialist for the calculation of the matching network and how different datasheet parameters can impact the circuit, but from the theory only the C / L values would be needed to calculate the matching circuit. I assume that the other parameters will not have a big impact.

    Please find more information in the datasheet at page 76 (chapter 7.3):

    https://www.ti.com/lit/gpn/trf7970a

    Best regards,

    Helfried