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DAC8218: DAC8218 output spur

Nanfang Liao
Intellectual 2085 points
Part Number: DAC8218

Hello Team,

My customer use our DAC8218, you can find the test waveform below, when CLR pin changes from low to high, we can find output has a big spur, the max voltage is about 3V, and last about ~us. Can you help to explain why there is a big spur? What's the root cause? Thanks

Regards,

Nanfang

 

  • 0
    TI__Genius 14220 points
    Hi Nanfang,

    Thank you for your query. I am checking this with the internal team. Will get back to you soon.

    Regards,
    Uttam Sahu
    Applications Engineer, Precision DACs
  • 0 in reply to Uttam Sahu
    TI__Mastermind 46290 points
    Nanfang,

    Could you provide any design files for this? It would be helpful to see the schematic and layout I believe. Any time there are fast digital edges on a DAC there is a chance to observe digital feedthrough to the analog output which could be the possibility here as the glitch appears to be incident with both rising and falling edges on the CLR signal.

    Do they see any other signatures of digital feedthrough? i.e. is anything similarly observable on the output related to the SCLK, CS, SDI, SDO, LDAC, etc. signals?

    Conceivable work-arounds would be either simply adding a series impedance, adding an R/C to smooth / slow the edge, or perhaps from "within" the MCU limiting the output drive capability of the digital pins. Most of the MSP430s and other simple controller platforms offer this capability.
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Nanfang,

    Any update on this thread?
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Nanfang,

    If the topic has been resolved, please let us know.