We are having issues programming the ADF4356 on one of our devices. The original design used the
ADF4350. Due to the RF requirements of the new design, the HW engineer decided to use the
ADF4356. A PIC16F was used in the original design to program the ADF. Space and time constraints
required that it be used in the new design.
We modified the IO to work with the new layout and ran the PIC16F with register values obtained by
following the example calculations in the ADF4356 datasheet. That failed.
Next we hooked up the evaluation board and captured the signals used to initialize and update the
ADF4356. Those register values were placed in the PIC16F. That failed.
We wired the PIC16F to the Evaluation Board in case we had incorrectly setup the ADF4356 on our
device. That failed.
The development was moved to an external breadboard and a PIC24H was used so that both SPI and
bit-bang signals could be used. The SDP uses SPI, but the PIC16F only has IO pins available = Bit-bang.
That failed.
Several articles were reviewed from the Engineering Zone. The information in the article "Large Spurs
at the Output of ADF5355" was applied as the final device has requirements that would benefit from
better spurs and other issues when changing frequency. That failed.
Tried different combinations of Initialization, Update and appending an additional R0. That failed.
We turned to tech support and they confirmed that the items shared should work. They were helpful
in asking questions to make sure we did not miss something needed to communicate. Unable to help
further, support has asked that we turn to the Engineering Zone to address our issues with others and
the technical staff who monitor the discussions.
We have found in the past that it is something simple that needs to be corrrected. Learning the how
and what then makes the PLL work. We have not found it for the ADF4356.
