AD9518 Calibration

Hello,

I’m using an AD9518-0 on my electronics board and now I’m facing some trouble to get the card “ready to serve” after an electrical reboot. In the FPGA connected to the AD9518-o(via SPI), I’m programming all the required settings right after the FPGA has booted. The only remaining issue is that I don’t manage do a VCO calibration(datasheet/p.33) after the initialisation. I’m doing this sequence:

  1. Configuration of all the registers (included PLLControl3 register/VCO cal nowbit = ‘1’)
  2. update registers
  3. wait 2 ms
  4. PLLControl3 register/VCO cal nowbit = ‘0’
  5. update registers
  6. wait 2 ms
  7. PLLControl3 register/VCO cal nowbit = ‘1’
  8. update registers

After this sequence the bit Digital lock detect stays low(PLL readback register/b0) and the output frequency is out of bound. This obviously means that the VCO is not calibrated. However if I launched again this sequence manually, it works.

So my question is :

Is there a certain time to wait before doing a calibration after a power-up? If yes how long?

  • 0
    •  Analog Employees 
    on May 7, 2015 8:57 PM over 5 years ago

    Hi Jnoirjean,

    > Is there a certain time to wait before doing a calibration after a power-up? If yes how long?

    No, but you should be sure that the power supplies are stable, and that the input clock is present.

    Looking at your sequence, I recommend changing Step 1 such that the VCO Cal Now bit is 0 on initial programming, and eliminate Steps 4-6. That should work. It seems to me that your sequence is interrupting the VCO cal sequence.

    -Paul Kern

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:01 PM over 2 years ago
    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