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Please provide support for AD9911 with no output

Question asked by Ovidiu on Jan 5, 2017
Latest reply on Jan 9, 2017 by Ovidiu



   I want to use AD9911 to generate a sinewave of a 1kHz, to see that it works. However, I can't get any output signal form the chip. I must add that I am using this chip with the evaluation board schematic on a separate board. I don't have the actual evaluation board. I managed to solder the chip with a reflow oven and then the other components manually. The only component that I don't have for now is the output transformer(on the output lines (IOUT)I have 2 resistors of 50ohms to 1.8V). The current consumption of the board is constant at 40mA no matter what(with 7V as supply voltage). I used both STM32F3 and RaspberryPi3 boars to send the commands via SPI. I configured the CSR to use one channel and two wire mode for MOSI-MISO (0x22)  and then I sent the frequency and phase folowed by the IO_Update pulse. I found similar information about this in the datasheet of AD9911. In between each command I sent a CS pulse(please see the attached file, the 2 ADS signals can be ignored, they are not part of this design). Then, I sent to 0x80 a value of 0xFF in order to read back the register content, but didn't receive anything. I also altered the clock polarity and phase, used the SPI at a different frequency but still nothing. SYNC_CLOCK is up and running as mentioned in the datasheet (1/4 of ref clock), AVDD/ DVDD are good, the loop filter is present. P0-P3 are tied together through a 0ohms resistor to AGND. DAC_RSET tied to AGND through 1K91 resistor.

   This is the second AD9911 chip that I am trying to get a sinewave from, and a different PCB also, same schematic as the evaluation board(without the output transformer part). I am missing something but can't seem to find for now. Any help or suggestions on this matter would be greatly appreciated.


Thank you for your time and have a nice day,