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ADIN1300 MDI Series resistor

Category: Hardware

Hello,

I’m in the process of designing a Gigabit Ethernet Interface based on the ADIN1300. I stumbled upon this Whitepaper about the topic while researching different magnetics.

There are resistors R1 to R4 in between the PHY and the Transformers since I didn't find any reference to this in the datasheet I would like to ask.

Is this recommended or good practice when designing a Ethernet Interface ?

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  • Hi Lukas,

    Resistors are not normally put in place on the MDI nets as shown here for normal applications. In some PoE applications there may be anti-surge resistors put in place as shown in this diagram, but at much smaller values, with a maximum of 4 to 5 Ohms.

    One other thing to note on this diagram, for an RMII interface the diagram mentioned a 50 MHz crystal but the ADIN1300 requires a 50MHz single ended clock in RMII mode (which could be sourced from the MAC of be a stand alone 50MHz single ended clock device).

    Best Regards,

    Mark

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  • Hi Lukas,

    Resistors are not normally put in place on the MDI nets as shown here for normal applications. In some PoE applications there may be anti-surge resistors put in place as shown in this diagram, but at much smaller values, with a maximum of 4 to 5 Ohms.

    One other thing to note on this diagram, for an RMII interface the diagram mentioned a 50 MHz crystal but the ADIN1300 requires a 50MHz single ended clock in RMII mode (which could be sourced from the MAC of be a stand alone 50MHz single ended clock device).

    Best Regards,

    Mark

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