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Does the DP83848i geneate the internal clock frequency of 125MHz from the system clock of 25MHz and is it possible to manipulate?

hgr
Prodigy 10 points
Other Parts Discussed in Thread: DP83848I

Hello TI support,

I´m investigating what possible frequencies our network device radiate with the background of a newly updated EMI specification. The DP83848i circuit seams to generate the internal clock of 125 MHz internally from the system clock input of 25MHz, and we would like to know if this 125 MHz is possible to turn off or manipulate in other ways? The manual does to state this.

Best regards

Håkan Green,

Hardware developer,

HMS Industrial Networks AB,

Sweden

 

  • 0
    TI__Mastermind 31600 points

    Håkan,

    In 100M operation, the signaling on the cable is 125MHz MLT-3.  As a result, a 125MHz clock is required for normal 100M operation. 

    In 10M operation, the cable signaling and the internal clocking are different.  Configuring the device for 10M operation would allow you to evaluate a normal operational mode without 125MHz signaling on the cable.

    Outside of normal operation, you can affect the internal clocking by applying a reset or configuring the DP83848 for power down mode.  I am not sure that this would be useful for your testing however.

    Patrick

  • 0 in reply to Patrick OFarrell
    TI__Mastermind 21801 points

    Hakan,

    To help with better supporting your future questions in Ethernet, please post any new Ethernet related questions into this forum.

    Thanks!

    John