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DP83822H: About EtherCAT system.

Kenji Ohno1
Genius 5095 points
Part Number: DP83822H


Hi Team,

My customers are using DP83822 to create EtherCAT system.

In this reference circuit, we may want to confirm two points.

www.ti.com/.../tidue46.pdf

1. Earth is connected, but is there a problem with this connection even when the board GND is floating?

2. Customers commonly made Earth 1 and Earth 2 products, so they can not separate them.Is there a problem with this?

Best Regards,

Kenji

  • 0
    TI__Mastermind 23675 points
    Hi Kenji,

    From the questions, it sounds like you have your system ground isolated from the Earth but no bleed resistor or decoupling cap, correct?
    You might see reduced immunity performance because if the RJ45 is floating.

    When you say that Earth1 and Earth2 are not separated, what do you mean? Where are these located?
    You generally do not want your system ground shorted to your Earth because of ground loops.
  • 0 in reply to Ross Pimentel
    Genius 5095 points
    Hi Ross,

    Is there a problem if there is a Bleed resistor or decoupling cap?
    May I think that resistance will decrease but communication problems will not occur?

    It seemed to be separated from ETH1_EARTH, ETH2_EARTH to the red circle in the figure attached before.
    I would like to know how it will affect the communication if I connect it.

    Best Regards,
    Kenji
  • 0 in reply to Kenji Ohno1
    TI__Mastermind 23675 points
    Hi Kenji,

    That bleed resistor and decoupling cap will not increase communication problems.
    It is for EMC/EMI.