# AD9218, what will the negative values be in binary mode?

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When my DAC output is from 0-1V, and is fed into 10-bit AD9218 which
is set to binary mode, what binary value will I get when the input is -10mV?

Re: AD9218, what will the negative values be in binary mode?
I assume you mean -10mV AC coupled into the AD9218 (it is internally
biased at 1/3Vdd)

You would have 1/200 of the negative dynamic range, or 1/100 of the
span range which gives -10/1024.

As the output is set for 2s complement, the output will run from +511
to -512 (Hex = 0x1FF at +511 to 0x200 at -512) for an input of 1Vp-p,
so in this case, you should get 3F6, rounded to the nearest integer.
(-10 decimal)

Cheers

PeteS

Re: AD9218, what will the negative values be in binary mode?
further to my other reply, if you are using offset binary, then you
will get N[off] - 10 (decimal). The output of the DAC at Vin(centre)
should be 0x200, so you would get 1F6.

Cheers

PeteS

Re: AD9218, what will the negative values be in binary mode?
Thank you Peter.

My digital output is from 0-1024 (1MHz sine wave 0 -> -1, 1024 -> +1) and
fed into the
10 MSBs of  DAC (TI DAC290x-EVM). Due to noise, the DAC has some below zero
values on oscilloscope (-20mV ~ 0.8V). When I connected this signal to ADC,
how do I
ensure that the digital output is the same (or nearly the same) value of my
original digital input?
(The requirement is such that after I captured the ADC O/P with logic
analyzer, plotted in
graph of 0~1024, it shows a sine wave without bad codes).

Re: AD9218, what will the negative values be in binary mode?
On 28 Nov 2005, Frank put down his happy meal and blurted:

I'm lovin' it.