AD9850
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The AD9850 is a highly integrated device that uses advanced DDS technology coupled with an internal high speed, high performance, D/A converter and comparator...
Datasheet
AD9850 on Analog.com
What is the maximum voltage difference allowed between AVDD and DVDD with an AD9850?
I would like to use DVDD = 3.3V, AVDD = 5V.
Is there a list of which pins are referenced to AGND and which are referenced to DGND?
Final question - is it worth the effort to use seperate supplies?
I'm using this in a 30-88MHz radio and the current design uses a single supply for the 9850.
Thanks
Randy
Hi Randy,
DVDD and AVDD should have the same supply. Kindly note that different specifications goes for 3.3V and 5V. Example:
There is no specific list, you should just take note what circuitry each pin is associated. You may start reading at the pin function description.
Yes, it is worth the effort to use separate supplies. However, this also comes with additional cost. You may use ferrite bead to isolate supplies as an alternative.
Are you sure you are using AD9850 for frequencies 30-88MHz? AD9850 comes with a 125MHz reference clock so it can output frequency up to 1/2 the reference clock. That means, 30-62.5MHz is okay. above 62.5MHz up to 88MHz, you are using the aliased images of the DDS output. You may want to use other DDS with higher reference clock like AD9851 (180MHz ref clock).
-Sitti
