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Original question:

AM3358: RMII reference clock

AM4378: CLKOUT2

Nancy Wang
Expert 8210 points
Part Number: AM4378

Hi,

The customer want to provide 50MHz reference clock from CLKOUT2. What's clock frequency error of the CLKOUT2?

  • 0
    TI__Guru**** 393215 points

    Hi,

    You need to source CLKOUT2 from the EXTDEV_PLL for this purpose. 

    SYSBOOT[18] can be used to supply a clock for external ethernet PHY devices. If SYSBOOT[5]=0, EXTDEV_PLL will be configured to 25MHz, if SYSBOOT[5]=1, EXTDEV_PLL will be configured to 50MHz. 

    The CLKOUT2 signal can be output on the XDMA_EVENT_INTR1 terminal. This terminal connects to one of seven internal signals through configurable multiplexers. The XDMA_EVENT_INTR1 multiplexer must be configured for Mode 3 to connect the CLKOUT2 signal to the XDMA_EVENT_INTR1 terminal. The default reset configuration of the XDMA_EVENT_INTR1 multiplexer is always Mode 7. Software must configure the XDMA_EVENT_INTR1 multiplexer to Mode 3 for the CLKOUT2 signal to be output on the XDMA_EVENT_INTR1 terminal.

  • 0 in reply to Biser Gatchev-XID
    TI__Expert 8210 points

    Hi,

    Thanks! But i want to know the frequency tolerance of CLKOUT2.

  • 0 in reply to Nancy Wang
    TI__Guru**** 393215 points

    This parameter is not characterized. However the EXTDEV_PLL is a low jitter DPLL, designed exactly for the purpose of providing external reference clock.