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DAC5681Z Problem

Other Parts Discussed in Thread: DAC5681Z

Hi there,

I have a FMC110 board with DAC5681Z. The problem is that the one of the DACs is not performing as it should, i.e. there is no output signal. The other DAC is OK.

The strange thing I noticed, is that when I do SW_sync, I can see the output of the signal for max 10 us, and after that the signal goes low or shows some other signal, probably the last 8 samples repeating. 

So the question is if somebody have had such a problem? It seems that some parts of the DAC are dead, but other parts of the DAC are working.

We tested the same FPGA configuration with another FMC110 and everything is performing OK.

I have attached an image from the scope, where you can see the output signal after SW_sync is asserted. 

BR,

Vladica

 scope_dac1.tif

  • Hi Vladica,

    If you have the SW_sync_sel set, then you must set SW_sync to 1 to enable the output. Ensure that both DAC5681z registers are set appropriately and that both devices get the SW_sync enable. If you are using the external LVDS_SYNC, please ensure that these differential LVDS signals are correct routed from the FPGA to the DAC. Perhaps you can try using external LVDS SYNC vs SW_sync to see if the both devices are working as expected. I would suspect maybe a possible problem with 1 of the DAC paths (solder issue, power, clocks...) as you indicate that another FMC110 works as expected.

    Unfortunately the FMC110 is a 4DSP board and is supported by 4DSP and it is very difficult for us to support that EVM - we do not have the FPGA platform or the FMC110 EVM. I would suggest contacting 4DSP if you continue to have issues with their FMC110 EVM to solicit their support.

    Let me know if we can help address any other device related questions.

    Ken
  • Thanks Ken,

    We are alredy sending the board for repair.

    BR,
    Vladica