AnsweredAssumed Answered

AD9834 wave below 1Khz

Question asked by MarkP on Sep 12, 2011
Latest reply on Oct 3, 2011 by MarkP

Good day..

 

I have an AD9834. I make de PCB and all seems to be running in a correct way. I find an online calculator so I can probe different things with the SPI commands. The link is: http://designtools.analog.com/dt/ad98334/ad9834.html#troubleshooting

 

I tried 10Mhz, 20Mhz and 5.6 Mhz and all is correct.

 

for my surprise, when I tried a 400Hz sine wave, the DDS output doesn't go below 1Khz. The SPI sequence for a 400Hz sine wave obtained from the calculator is:

 

2100 4598 4000 8000 8000 C000 E000 2000 (Hex format)

 

I read the AN-1070 app, and i tried to make some hand calculation and I think that the calculator is correct too.

I also re-read the AD9834 datasheet to see if I missed something, but i could not see it.

 

Do you have an idea of what might be wrong ?

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