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ADF5355 Init Problem

Question asked by tooony on Feb 1, 2018



i try to control a microwave using the ADF5355 from the microcontroller ATmega328P. The microwave generator is a custom board running with 38,4 MHz reference frequency. With the ADF5355 we want to generate signal withe frequency range from 9,5 GHz...10,5 GHz (10 GHz for normal). The ADF5355 Board is a custom board developed from an extern company. I got the information that the setup runs with a 38,4 MHz reference clock and that i should use an PFD of 76,8 MHz.


My code on the microcontroller generates the register entries. I validated the generated resgisterentries and the look like the same as in the Evaluation Board Control Software. So far so good - But i cant get the ADF5355 working and i get no lock.


At first i try to geht the init sequence to work. Here i have (analog to the datasheet) to use the init sequence, which init first with the halved PFD ( init for pfd > 75 MHz). Here is my first question: Is the halved PFD the half of the PFD in normal operation or the the half of the reference clock?


Can you explain more about the workflow to init the ADF5355? Here are my register entries for the halved PFD part of the init sequence (from register 12 to 0):




After init with halved pfd i expected to get a lock, but i dont get a lock. When i run the complete init sequence for pfd > 75 MHz i get a other frequency then 10 GHz. I use the digital lock, so i expect that the muxout pin goes to a stable high level (3,3 volt) - is that right?


I hope for some help to geht the ADF5355 working. In addition is the screenshot of the configuration for the wanted setup in normal operation (10 GHz with PFD 76,8 MHz).