when using ad9957 eval board , i disconect c51 c52, and set the W7 jumpler to select XTAL , short the R4 and R11.
But the AD9957 eval software showed the PLL is not locked .And when i watched the sync_clk , the frequency is not fixed and float.
Yes, you have to populate the loop filter components when you are going to use the XTAL with PLL. Refer to page 3 UG-208 for more information.
dos pll_loop_filter circuit must be connected for lock the pll with outside xtal ?
thanks i have tryied your advice and it work.
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