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No output for AD9910

Question asked by hpkamen on Feb 26, 2017
Latest reply on Mar 16, 2017 by mcee

Dear Sir/ Madam,


I encountered some issues when using DDS chip : DDS chip circuit is shown below , using FPGA  to control CSB,CLK,SDIO,IO-update pin. And the sequence diagram is shown in the following figure, using oscilloscope to probe tests: ref-clk=40MHZ, amplitude 1.8V, ref-clk-out output DC 1.8V,no output for sysnc-CLK. No signal on the output pin. I woner knowing the following questions:


1,Whether or not the input signals 40MHZ, 1.8V for ref-CLK meets AD9910's requirement, whehter or not no output for ref-CLK-out mean that the chips didn't work, or no output of sysnc-CLK?


2,Whether or not the time series of FPGA has problems (have little timing differences in PDF), why there is no output signal? are Registers not written in?