[time-nuts] Question about AD9832 "I out Full Scale" (what does it mean?)

David G. McGaw david.g.mcgaw at dartmouth.edu
Fri Nov 18 04:27:10 EST 2016

There is something wrong with the example.  The output is single-ended, 
so using info from the AD9832 data sheet with Rset=3.9K and Rload=300 
ohms as shown in the EVB schematic, it should go from 0 to 3.88mA and 0 
to 1.16V.  Figure 12 shows only half this, including only about .3V DC 
bias instead of .58V.

I apologize.  As a former Analog Devices applications engineer (Digital 
Audio Group), I find this data sheet and user guide poorly written.  
They have a lot of digital and almost no analog information.

David N1HAC

On 11/17/16 11:09 PM, Richard (Rick) Karlquist wrote:
> Trying to figure out what "Iout Full Scale" means on the AD9832.
> Some time nuts may have used this one.
> On page 7 of this doc:
> http://www.analog.com/media/en/technical-documentation/user-guides/UG-313.pdf 
> It shows the AD9832 output as 572 mV peak to peak
> across 300 ohms.  This works out to 1.9 mA peak to
> peak current through the resistor.  But Rset on the
> board is 3.9K, which is supposed to give a value
> for so-called "Iout Full Scale" of 3.878 mA.
> I would have thought (just guessing) that peak to
> peak output current would be equal to Iout Full
> Scale, but it appears to be only half of that.
> Can anyone clarify this?
> Rick
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