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providing jumper selectable dual interface with Copper & Fiber

gannu gour
Prodigy 110 points

hi

my intention is to provide a jumper selectable fast ethernet connectivity via copper(RJ45) or Fiber mode

as per the reference design 0 Ohm resistor are placed on TD+,TD-,RD+ and RD- for both copper interface and fiber interface. it is required not to solder this 0 ohm resistor in case of avoiding that particulr interface.

Please see my attached schematics. Here with H9,H11,H13 & H12. I provide the jumper selectable feature. 

My doubt is whether I can put these jumpers. I suspect some Signal integrity issues if i introduce such jumpers.

Kindly let me know whether I can proceed with my jumper based concept or not.DP83620 sch .docx

 

  • 0
    TI__Mastermind 23675 points

    Hi Abitya,

    We typically do not recommend doing such an application because the trace impedance needs to be controlled. However, if you can find the electrical specs of the header and jumper you plan to use, they might still be within an acceptable range. One of the main killers to doing a header implementation is impedance matching over the higher frequency range. 100Mbps MTL3 signaling will have rise/fall times of 3-5ns. 100BASE-FX signaling can have rise/fall times around 1ns. 

    You might need to use a specific material header (possibly gold plated) to ensure signal quality. I would reach out to your header vendor and ask them for a spec table on the header you intend to use.

    Kind regards,

    Ross

  • 0 in reply to Ross Pimentel
    Prodigy 110 points

    Thanks Ross

    I was planning for a general gold plated Berg strip

    Kindly let me know if this would suffice.

  • 0 in reply to gannu gour
    TI__Mastermind 23675 points
    Hi Aditya,

    You should check with the header vendor for electrical specs of this component and verify with them the impedance measurements.

    Kind regards,
    Ross