Wrong SPI description of the AD5621

I have been fighting against the AD5621 and couldn't make it work, until I realise that the SPI description in the datasheet is wrong. It says everywhere that the SPI works latching on the falling edge of the clock, but it actually work on the rising edge.

I write this for everyone to know.

attachments.zip
  • 0
    •  Analog Employees 
    on Oct 4, 2012 1:27 PM

    Hi,

    The AD5621 is falling edge sensitive so your results are surprising. Can you display the plots with chip select SYNC signal also? My suspicion is that there might be something strange happening between SYNC and the number of clocks.

    Can you display all 3 signals together?

    Regards,

    Padraic

  • 0
    •  Analog Employees 
    on May 3, 2013 12:37 PM

    Hi daguiam,

    Im not familiar with the ezkit so, I'll assuming that the buffers are in the ezkit while the dac is connected externally, right?

    Could you confirm that the glitches in the plot is due to an incorrect ground reference in the test proves?

    Could you verify that the connections are correct?

    Can you add the Vout pin in the plot?

    Regards,

    Miguel

  • I ran into some issues using the same AD5621. I can not find a way to program it and I tried both falling edge and rising edges. The DAC output stays at 0V from powerup.

    I attach the scope signals and the word I'm programming is 0x8F1. I am programming using an ezkit lite 21369 and a SPORT2 port and gating both the clock and the SYNC line with a MISCA buffer on the PBEN line of the DAIs, that is why the signals rise after the transmission.

    Do you have any idea of what is going on?

    Thanks!

  • Hey,

    I found the error due because of what you suggested. I was confident my PCB layout was correct but the SCLK and DATA lines were switched. But I overlooked this. The ch2 is the Vout of the DAC but there is an RC low pass filter, explaining the slow rise

    Since the ADSP DAI pins are so easily reconfigured in software this error was easily resolved.

    Thank you for your help!

  • 0
    •  Analog Employees 
    on Aug 2, 2018 4:40 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin