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TLK110 PHYAD0-4application?

MKolb
Prodigy 70 points
Other Parts Discussed in Thread: TLK110

I am currently reviewing TLK110 for the Ethernet PHY between a 32 bit microcontroller MII Ethernet port and connector.  I have never designed an Ethernet port into an embedded controller board before so I am in the process of learning as much as I can about this.  My question about this particular part concerns the PHYAD pins.  What is the point of being able to address multiple TLK110s when there is only one MII interface?  What can the multiple addresses be used for?

  • 0
    TI__Mastermind 31600 points

    You are correct.  The MII connections between an Ethernet MAC and and Ethernet Phy will typically be 1-to-1. 

    The Phy address pins are used for register addressing.  The MDC/MDIO pins that are used to access Phy registers can be shared.  When multiple devices share the same MDC/MDIO pins, the Phy addresses of the multiple devices can be set to different values so that the multiple devices can be configured and read independently. 

    Patrick

  • 0 in reply to Patrick OFarrell
    Prodigy 70 points

    Can you provide an example of where this would be useful?

  • 0 in reply to MKolb
    TI__Mastermind 31600 points

    One example would be a failover application.  Consider an MCU or processor with two exposed MII ports and a single MDC/MDIO register interface.  Each MII port connects to a single port Phy.  The MDC / MDIO pins from the MCU or processor connect to each Phy.  The MCU or processor directs Ethernet traffic through one Phy.  If the Phy loses link, the MCU or processor can detect that through polling of the registers  at that Phy address or through an interrupt from the Phy.  Based on that loss of link, the MCU or processor can direct Ethernet traffic through the second Phy.  The MCU or processor can then monitor the second Phy at its Phy address.