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CLK104 PLL Lock

dchien

The CLK104 clock board on my ZCU208 evaluation board does not have all PLL lock LEDs on. The clock distribution PLL (U2) has its lock LED (DS1) on, but the DAC PLL (U7) has its LED (DS3) off and the ADC PLL (U5) has its lock LED (DS2) off. Do I have a defective CLK104 board? What can cause the ADC and DAC PLLs not locking (LEDs off)?

Thanks!image

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  • What I recall is that the ADC/DAC PLL lock LEDs only turn on when you have configured the LMX devices to synthesize a sample rate clock (the AMD doc UG1437 refers to them as RF PLLs). In this scenario you need to cable the RF PLL outputs from the CLK104 to the zcu208.

    However, if you are using CLK104 to deliver a reference clock to the RFDC internall PLLs (ex: 245.76MHz), these connections are made through the RFMC2.0 connector. This is the default configuration of CLk104 for Avnet RFSoC Explorer. In this scenario only the LMK LED lock will activate as the LMX PLLs are not used.

    My board is being used by a colleague this week, but I can confirm early next week.

  • in reply to mbrown

    In my setup, the outputs of the ADC RFCLK from CLK104 are connected to ZCU208 ADC CLK inputs and outputs of the DAC RFCLK from CLK104 are connected to ZCU208 DAC CLK inputs. When ADC and DAC are used in the design, I believe both LMX2594 PLL lock LEDs should be on. Please verify the LED status when you get your board back next week. Thanks.

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  • in reply to mbrown

    In my setup, the outputs of the ADC RFCLK from CLK104 are connected to ZCU208 ADC CLK inputs and outputs of the DAC RFCLK from CLK104 are connected to ZCU208 DAC CLK inputs. When ADC and DAC are used in the design, I believe both LMX2594 PLL lock LEDs should be on. Please verify the LED status when you get your board back next week. Thanks.

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