3 Replies Latest reply on Aug 7, 2020 3:52 AM by YashwantK_46

    Recommended 52Mhz Oscillator for FX3?

    GrHa_3282776

      Hi,

      I having problems specifying and sourcing a 52 Mhz CMOS oscillator at 3.3V for the CYUSB3014.  Is there a recommended PN?  And is there a reference schematic design and layout?

      Don't need the extra processing speed now, just trying to future-proof.

      Thanks,

      Greg

      Electronics Test Engineer

        • 1. Re: Recommended 52Mhz Oscillator for FX3?
          YashwantK_46

          Hello Greg,

           

          The AN70707 recommends using ASEMB-19.200MHZ-LY-T (for 19.2 MHz clock).
          You can use same company's 52 MHz clock oscillator provided the phase noise requirements, mentioned in Table 6, Section 5.1.2, Page no. 11 of AN70707, are fulfilled.

           

          You can take a look at this thread as a reference for the phase noise requirement to be met: FX3 Oscillator Phase Noise

           

          Unfortunately, we don't have any reference schematic or layout for such a design.

           

          Also, as mentioned in the cyu3system.h file,

           

            The SYS_CLK_PLL value is 416 MHz if the input clock frequency is 26 MHz or 52 MHz;

              and it is 384 MHz if the input clock frequency is 19.2 MHz or 38.4 MHz. The

              SYS_CLK_PLL frequency can be changed to 403.2 MHz from 384 MHz by passing appropriate

              parameters to the CyU3PDeviceInit function.


          - Using a 19.2MHz or 38.4MHz and setting the appropriate parameters in CyU3PDeviceInit function would still make the input clock frequency to be at 403.2 MHz (which makes the max GPIF II clock frequency as 100MHz (max)).

           

           

          Regards,
          Yashwant

          • 2. Re: Recommended 52Mhz Oscillator for FX3?
            GrHa_3282776

            Thanks,

            Are there ANY benefits to increasing the clock oscillator frequency?

            Greg

            • 3. Re: Recommended 52Mhz Oscillator for FX3?
              YashwantK_46

              Hello Greg,

               

               

              The overall performance of the system would improve when a higher clock oscillator is used.
              The PLL dividers will be adjusted based on 416MHz (instead of 403.2MHz, when using 19.2MHz or 38.4MHz) accordingly when using a 52MHz oscillator and there will be improvement in the corresponding DMA clocks, etc.

               

              Regards,
              Yashwant