I have a customer who is using the DAC5689 on an existing production board. He configures the device to be in half rate bus mode. He used both data buses and hios issue is when CLK1 is at 200MHz, CLK2 at 400MHz, the output functions properly on 2 out of 10 boards. What he found was if he lowered the CLK1 to 190MHz and CLK2 to 380MHz the converter functions as expected????? He also found that when a working board reaches 60 degrees C failure occurs.
The clock source is a National Semi LMK04033 that does not have CMOS outputs. He uses LVPECL output ( and inverted out) and a Thevenin's equivalent circuit on the balanced DAC5689 CLK input that consists of 49.9 ohm resistors from the +/- CLK inputs, tied together going thru another 49.9 ohm resistor to ground. After much experimentation this circuit worked the best.
I know this is NOT much info but it begins the conversation. Please find the register file attached as well as Spectrum analyzer views of working, failure begins and then final failure results.
-Tom-