AnsweredAssumed Answered

issue with ad9912 eval-board

Question asked by mgruber on May 19, 2011
Latest reply on Jul 6, 2012 by MarkusGruber



I used some DDS eval boards already in the past (such as the ad9852).


Now I have a new ad9912 board here but for some readson I can not get this board working.


I attached a clock signal on SYSCLK and attached the power connections (1.8/3.3V on TB1, VDD_DACDEC (J32) and VDD_DAC3 (J11).


The software installation was finished without any error and the board was found immediately. I updated all values (SYSCLK 18.4 MHz), multiplier to 40x (the Loop-filter was already poulated on the board, I only had to swithc the resistor (R3/R24 in the schematics, on the board R3 -> R5 and R24 is R3)


I tried to generate various signals but on the filtered output I do not get anything gut some noise!


Did I forget something (attach some required power supply - but in the manual was mentioned that the J16/J17 power supllies ared fed by the AVDD, I also checked if the required 0 ohm bridges are present -> they are)


I also checked if the CLCK amplitude is sufficient. I have got approx 900mV to 1V (differential). According to the data sheet (min. 632 mV are r'quired) it should be ok.


Finally I have to ask myself if I am simply too stupid to get this board running or have I got some defective eval-board?