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DAC8562TEVM: DAC8562TEVM: digital glitches at the analog output

Sergio Pesenti
Prodigy 20 points

Part Number: DAC8562TEVM
Other Parts Discussed in Thread: DAC8562, , DAC8831, DAC8N002

Hello,

We are currently evaluating the DAC8562 using the DAC8562TEVM board. Here below is a capture with the oscilloscope of the DAC output. You would have noticed the large amount of digial glitches at the analog output. Is this expected or you suspect something's wrong in our setup?

dacoutput.png

Looking forward to your feedback, I wish you a nice day.

Best Regards.

Sergio Pesenti

  • 0
    TI__Guru 55803 points

    Hi Sergio,

    What is happening at the oscilloscope trigger time? Are you streaming data into the device? Is there significant clock feedthrough happening here? Really this looks like a noise, oscilliation, or scope problem.  This behavior is not expected of this device.

    Are you using the on-board reference? Is the EVM well grounded with the supply and the scope?

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 20 points

    Hello Paul,

    Thanks for your support.
    You can consider this case closed.
    We solved the problem by adding SMA connectors to capture the two DAC outputs in a clean way.
    As you can see here below, we used the AGND from TP4 and the outputs are routed without crossing other signals.
    I suggest you also add them to the design. 
    We would have missed the best glitch-spec DAC if it wasn't for that.
    Best Regards.
    Sergio 
  • +1 in reply to Sergio Pesenti
    TI__Guru 55803 points

    Hi Sergio,

    I absolutely agree with you about the EVM.  I am actively EOL these older EVMs and pushing for replacements that enable evaluation of key analog specs on the relevent devices.  Similar to this EVM for the DAC8831.

    The DAC8562 is on the list! Hopefully out next year.  

    We hope to have the DAC8N002 released in december/january.  It will have similar glitch performance though it will lack a reference. The version with reference, DAC8R002 will likely be released in the February/March timeframe. 

    Thanks!

    Paul