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DP83867E: clk_out operation clarification

Part Number: DP83867E

Team,

My customer has the following question: 

At this point I’m using the DP83867E clk_out pin for a fixed 25MHz copy of the input clock on one of the DP83867E devices and generating the125MHz clock elsewhere.

Could you confirm the following default operation for clk_out is correct ?  Also, which strap pin is used for the clock_out disable?  It’s not clear in the datasheet.

 

From section 9.3.3 of the data sheet:

 

Using the I/O Configuration register (address 0x0170), the DP83867 can be configured to output these internal

clocks via the CLK_OUT pin. By default, the output clock is synchronous to the X_I oscillator / crystal input. The

default output clock is suitable for use as the reference clock of another DP83867 device.

 

 

Regards,

Aaron

 

  • Hi Aaron,

    That is correct, the PHY will generate a copy of 25MHz input clock by default on the clock out pin. However, there is no strap to disable on the 48pin device. This is a typo in the datasheet and will be fixed in the next revision. The clock out can be disabled through register 0x170.

    -Regards,
    Aniruddha