Max value for A and B counters in ADF41020

Hi all,

I am working with the evaluation board for the ADF41020 Microwave PLL Synthesizer. According to the datasheet of the ADF41020, counter A should be able to count to a value up to 63 and B up to 8191 (page 8 of datasheet, in "A COUNTER AND B COUNTER" section).

But when using the Analog Devices Int-N PLL software, the maximum N value I can enter for this board correspond to A counting up to 31 and B up to 4096. It looks like there is one bit in each counter that is unused by the software.

Why is this so? Am I misunderstanding something about how the ADF41020 PLL works, or is this a bug in the Int-N PLL software?

Thank you for your help.

EDIT: For me this bug appears in the "Main Controls" tab of Int-N but can be avoided by writing directly the registers in the "Registers" tab.



For me this bug appears in the "Main Controls" tab of Int-N but can be avoided by writing directly the registers in the "Registers" tab.
[edited by: Happy_User at 9:55 AM (GMT -4) on 29 Oct 2021]
  • +1
    •  Analog Employees 
    on Nov 2, 2021 3:15 PM

    Hi,

    You are correct there appears to be a bug in the software. There seems to be a max limit on the N value box of 262175 which is not correct. The max N value should be allowed to be 524287. 

    The workaround we have right now would be to manually write the register contents as you have suggested