This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83848I: Failed to connect

Part Number: DP83848I


Dears,

PN#:DP83848NRTAR 

Please help to analyze the problem: When 3516DV300+83848 in CD54 shell, It would fail with 50m CAT7 wire.

1. The following figure are based on the test results of CAT7 network cable of 50 meters;

2, It can be seen that the effect of 83848 is slightly worse than RTL8201 and CPU built-in PHY;

3. The difference between CD54 and CR34 is that CD54 has a 10cm FFC line between the network transformer and the PHY, while CR34 is directly connected on the PCB board.

4. "×" indicates that the network is disconnected. 

Schematic diagram is as shown in the attachment

3516DV300+83848.pdf

  • Hi Verna,

    I need some clarification on your schematics.

    • Where is the network transformer is being used? In the schematics we saw the magnetic transformer components is on the PHYs board instead of being used in between the cable line.
    • Does the shorter cable is linking up fine?
    • Could you run without the POE to check for linked up?

    --

    Regards,

    Hillman Lin

  • HI Hillman,

            1The transformer is between PHY and J22J22 is a connectoras the picture shows.

            2Yesshorter cable and unshielded cable is ok. 100M cat6 cable and 1M cat7 cable is okbut 50M cat7 is not ok.
            3Run with PoE or without is not affect the results.

  • Hi Verna,

    Are you using the same transformer in CR34 and CD54? Is the passing unshielded similar to cat7? Can you also check the performance without connecting the shield of the cat7 cable to ground? If the transformer are same than the only different we see is in the ground connection of shield VS. unshielded cable.

    --

    Regards,

    Hillman Lin

  • Hi Hillman,

    1Yes,same transformer.

    2cat7 is shielded cable.

    3Whether it is grounded or not is the same phenomenon.

  • Hi Verna,

    I will discuss this issue to the team and get back to you by tomorrow.

    --

    Regards,

    Hillman Lin

  • Hi Verna,

    Is the passing result for unshielded cable [the one that you mention earlier] similar to CAT7? Is the CAT7 cable shield connected to the connector J22? Is it possible to remove the ground connection of J22 and then do the test?

    --

    Regards,

    Hillman Lin

  • HI Hillman,

    1No,Unshielded cable is normal,there is no problem with using cat5e and cat6 .
    2Not connected to J22.
    3Whether it is grounded or not is the same phenomenon.

    Regards,

    Verna

  • Hi Verna,

    Does your final application use : 

    1. 10 cm FCP wire?

    2. CAT7 cable?

    As this use case if off the normal case so we dont exactly know the reason of shorter cable with CAT7. One possible thing is that as CAT7 has poorer return loss, so it may be interfering with PHY with additional discontinuity of FCP cable. 

    --

    Regards,

    Hillman