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Observer sasisaketh
Observer
2,005 Views
Registered: ‎09-23-2016

Can Zynq PL fabric clock be used to clock an external chip like Ethernet PHY ?

Hi,

 

I want to know the recommendation from XIlinx on whether the Zynq PL fabric clock be used to clock an external chip like Ethernet PHY ?. In my implementation i have used the IOPLL to generate PL fabric clocks namely FCLK0 and FCLK1. The FCLK1 is used as input to the Clocking Wizard and 4 output clocks have been derived. Can these four clocks be constrained to Zynq PL IOs as outputs and be used as clocks for four external chips respectively ?

 

Thanks,

Saketh

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Teacher drjohnsmith
Teacher
2,000 Views
Registered: ‎07-09-2009

Re: Can Zynq PL fabric clock be used to clock an external chip like Ethernet PHY ?

depends what yo mean by PHY clock.

 

if its the 25 Mhz ref clock sort of thing into the PHY,

   these normally have very tight tolerance requirements at the PHY

      its very unlikely the Zynq output without lots of external circuit would meet the phy requirements.

 

If its a clock with data to the phy, then the zynq output is perfect.

 

a bit of a circuit and more information would be of use.

 

 

 

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Observer sasisaketh
Observer
1,882 Views
Registered: ‎09-23-2016

Re: Can Zynq PL fabric clock be used to clock an external chip like Ethernet PHY ?

Hi John,

 

Thanks for the reply.
Yes, this is for the reference clock for PHY - DP83848-EP. The tolerances are indicated in the datasheet of the device.

The maximum acceptable ppm is +/-50 ppm and jitter of max 800 ps for 25 MHz clock source.

 

Regards,

Sasi

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