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    Examples for AD9547/48 Evaluation Software

    Ilnur655

      Hello!

       

      We use AD9548 to synchronize two remote devices via a GPS module (1pps). We also downloaded AD9547/48 Evaluation Software from your site. Could you please send us examples of work with this program, that is, file format (*.stp).

       

      Thanks in advance!

       

      P.S. We use external clock frequency at 16 MHZ.

        • 1. Re: Examples for AD9547/48 Evaluation Software
          pkern

          In order for us to configure a setup file for you as a starting point, we need the following:

           

          1. System clock input frequency

          2. Desired input and output frequencies

          3. Desired loop bandwidth (if any)

          4. Any other special reqirements

           

          Bear in mind that GPS applications require either a TCXO or OCXO for the system clock source. The minimum loop BW for using an xtal for the system clock is about 50 Hz.

          • 2. Re: Examples for AD9547/48 Evaluation Software
            Ilnur655

            Hello!

            1. External clock frecuency at 16 MHz (the most desirable value)

            2. System clock freq. 640MHz

            3. Reference input 1Hz   (GPS 1-pps, the most desirable option)

            4. DDS freq. 63MHz (or greater)

            5. Output 16MHz (or any)

            6. Any bandwidth

            Other special requirements isn't important for us.

            At the moment we failed to achieve synchronization. We can not set the correct settings for the profile of Reference A.

             

            Could you send the file (*.stp) on my email: ILNUR655@gmail.com

            Thanks in advance!

            • 3. Re: Examples for AD9547/48 Evaluation Software
              pkern

              Dear Ilnur,

               

              Attached please find a sample setup file and eval board instructions. If you download the evaluation software from www.analog.com<http://www.analog.com>, you’ll be able to load this file.

               

              For best performance, we generally run the DDS between 100 and 250 MHz, and we generally run the system clock close to 1 GHz.

               

              Have a look at these files and let me know if you have questions.

               

               

              -Paul Kern

              • 4. Re: Examples for AD9547/48 Evaluation Software
                Ilnur655

                THANK YOU!!!

                • 5. Re: Examples for AD9547/48 Evaluation Software
                  pkern

                  You're welcome!  The AD9548/47 is an amazing chip with phenomenal flexibility.

                   

                  We're always open to suggestions to improving the doucmentation if you see any areas where the features aren't adequately explained.

                   

                  -Paul Kern

                  • 6. Re: Examples for AD9547/48 Evaluation Software
                    joeka

                    Hi,

                     

                    I also downloaded the evaluation software (and bought the evaulation board) to make some experiment about the AD9548 component.

                    Actually, i'm trying to use the AD9548 to synchronize a device with either a 1Hz reference or a 32 Mhz reference.

                    I made a priority to prefer the 1 Hz reference when available, or the 32Mhz reference when not.

                     

                    However i just don't understand how to fill the parameters in "profiles" . I failed to achieve synchronization. I can't set the correct settings for the Reference A and B Profiles.

                     

                    To resume, i'd like to have :

                    1Hz and 32 MHz reference inputs

                    32Mhz output frequency

                    800MHz primary clock VCO

                     

                    Could you post the file (*.stp) to have a starting point.

                     

                    Thank You

                    • 7. Re: Examples for AD9547/48 Evaluation Software
                      pkern

                      Dear Joeka,

                       

                      I'm happy to create a setup file for you, but before I do so, I need to ask the following:

                       

                      In order to lock to a 1 pps signal, some changes are needed for the eval board:

                       

                      1. You must use a TCXO, OCXO, or other stable source (like a low noise signal generator) for the system clock. How are you planning on doing this and what is the frequency?

                       

                      2. You must DC couple the 1 pps reference input.

                      • 8. Re: Examples for AD9547/48 Evaluation Software
                        joeka

                        Dear Paul,

                         

                        Thank you for you answer.

                         

                        I will use the AD9548 on a custom card where i 'm already using a 32MHz oscillator (ECS-3525-320-B-TR) but as you said it seems to be not a TCXO.I can add another crystal, my question is, which one (at least which frequency) is the better for the application i'm developping ? ( I may try with this one : FOX924B-19.440. I also have a DG535 generator but i'm not sure it would be enough stable).

                         

                        In a first time i would like to test it on the evaluation board by using a 1Hz reference signal.

                         

                        Other question : in the AD9547/AD9548 Evaluation Board, on page 3, do modifications need to be done directly on the board in case of using a 1pps signal that is , i need to unsolder C39 and replace it by a 0 Ohm resistor to have a DC-coupled on ref BB and i need to remove R23 ?(Actually, R23 is already missing on the eval board : is it normal ?)

                         

                        For the 1pps signal it would be generated on the same custom card (IRIG-B signal).

                         

                        Thank you

                         

                        Joeka

                        • 9. Re: Examples for AD9547/48 Evaluation Software
                          joeka

                          Hi again,

                           

                          I saw that when I put a 1Hz input frequency, i had to put at least 62500000 in Feed Back Divide (S).

                          Can i put a fewer value (32000000) ?

                           

                          Thank you !

                          • 10. Re: Examples for AD9547/48 Evaluation Software
                            pkern

                            Hello Joeka,

                             

                            In general, the part works best when the DPLL output frequency is at least 100 MHz, as it synthesizes at sine wave, and better slew rate results in better performance. Also, the post dividers on the part are very deep can capable of dividing all the way back down to 1pps. It's possible to directly synthesize 1Hz directly, but I can't think of a reason why you'd want to.

                             

                            For the TCXO, the only recommendation is to avoid a frequency that's integer related to out output frequency. For your application, a TCXO with a 19.44, 19.2, 38.4, or 38.88 MHz is ideal. There's a place for a Vectron TX-700 on the eval board, and we've mounted many devices from Vectron, Connor-Winfield, NDK, Suntsu, Rakon, Epson, and Valpey-Fisher. We don't endorse one vendor over another.

                             

                            > Do i need to unsolder C39 and replace it by a 0 Ohm resistor to have a

                            > DC-coupled on ref BB and i need to remove R23 ?

                             

                            Yes. Although you will probably find that putting a 10ohm series resistor will work better (less ringing).

                             

                            For the TCXO, there's a good diagram in the "Input/Output Termination Recommendations" section of this datasheet: http://www.analog.com/static/imported-files/data_sheets/AD9557.pdf

                             

                            This is the best way to hook up a TCXO to the AD9548 as well.

                             

                            -Paul Kern

                            • 11. Re: Examples for AD9547/48 Evaluation Software
                              joeka

                              Hello

                               

                              Thank you for your answer, I really appreciate and I'm sorry to disturb you once again.

                               

                              There is still something I don't understand. I need the AD9548 to synchronize a  32 MHz signal with a 1Hz signal : in other words i need every rising edge from 1Hz clock to be in phase with the 32MHz clock.

                              So I have to put something like 128 Mhz for DPLL output frequency and then i need to divide by a factor 4 to have the 32 Mhz I need in output clkout. Is it correct ?

                              Unbenannt.jpg

                              • 12. Re: Examples for AD9547/48 Evaluation Software
                                pkern

                                Hi Joeka,

                                 

                                Yes. That's correct. Actually, the DPLL output can be any integer multiple of 32 MHz. and it will work fine. The evaluation board has a 240 MHz low pass filter at the DPLL output, so I'd recommend setting the DPLL output frequency to 224MHz and doing a /7. Don't worry. The duty cycle will still be 50%.

                                 

                                One more thing: when setting up the DPLL, be sure to set the threshold priority to a value higher than any of the priority settings in the DPLL profiles. For instance, set the threshold priority to >=2 if you have two profiles where one is priority 0 and the other is priority 1. This will guarantee that you will maintain the same static phase offset (and have output phase slewing) as you switch references.

                                 

                                The other requirement is that the R divider always be one.This may be a problem for you, as you're limited to an input frequency of 10 MHz if the R divider must be one. Can you do a /4 on the 32 MHz input?  Keeping the static phase offset constant for the 1 pps is not a problem.

                                 

                                -Paul

                                • 13. Re: Examples for AD9547/48 Evaluation Software
                                  joeka

                                  Hi,

                                   

                                  I'm using a 32MHz oscillator on a custom card but i'm using a cyclone III on this card too, so I would be able to do a /4 (alt_pll) on the 32MHz to respect the limited input of 10 MHz frequency in input of AD9548.

                                   

                                  I ordered a Connor WinField D75F-019.44M this morning on DigiKey. I wonder if the ppm precision would be enough.

                                   

                                  I really appreciate the help you gave to me and I will let you know as soon as I get the TCXO.

                                   

                                  Joeka

                                  • 14. Re: Examples for AD9547/48 Evaluation Software
                                    pkern

                                    Hello Joeka,

                                     

                                    We've used the T604s from them, and if the D75F is at least as good, we're all set. I don't think we've ever tested a TCXO that wasn't good enough.

                                     

                                    -Paul Kern

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