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Require to transmit fast ethernet signals with recovered clock for 100BaseFX operation using MII

Hemant Ghayal
Intellectual 265 points

Other Parts Discussed in Thread: DP83620, DP83640, DP83630

Which Phyter chip I can use for operating it in a way where the ethernet received clock can be used for transmitting ethernet signals, instead of using the crystal clock for this purpose. Also would like to know the register settings / external connections for using the phyter chip this way. I will be using the chip in 100 Base FX mode and would like to operate it through MII interface.

  • 0
    TI__Mastermind 31600 points

    What is your goal?  Are you wanting to operate without the crystal?

    Patrick

  • 0 in reply to Patrick OFarrell
    Intellectual 265 points

    Hi Patrick,

    It is not the goal to operate the phy without a crystal. The goal is to be able to have  phy on one end as clock master and the other end as clock slave. The slave side should be able to send its ethernet frames using its RX_CLK  on MII. The crystal may still be needed as a stable clock to assist the chip operation and clock recovery.  And the crystal on the master side will be the clock master for both ends. It is also permitted that till the link is established the  slave may have its TX_CLK derived from its crystal, but after that the TX_CLK on slave MII should be synchronized with its RX_CLK.

    You could say that it is sort of synchronized ethernet application using fast ethernet in which both sides of an ethernet link have only one MII clock master.

    Regards,

    Hemant Ghayal

  • 0 in reply to Hemant Ghayal
    TI__Mastermind 31600 points

    Understood.  I just wanted to double check you expectations.  The crystal (or some reference clock source) is always required.

    We do have devices that support a Synchronous Ethernet mode in which the 100Mbps clock recovered from the received data is used to clock the transmit data.  We have an application note with more details on the functionality:

    http://www.ti.com/litv/pdf/snla100

    The devices that support this mode are the DP83640, the DP83630, and the DP83620.  If you are not planning to use IEEE 1588 functionality, then the DP83620 would be the part for you to use.

    Patrick

  • 0 in reply to Patrick OFarrell
    Intellectual 265 points

    Thank you patrick. We will go through the matter suggested by you.

    Regards,

    Ghayal