I appreciate it if you could suggest me a AD7687 Datasheet explaining why the Common-Mode Input Range of AD7687 is up to VREF/2 + 0.1 V.
Thank you for your help in advance.
The AD7687 accepts differential anti-phase inputs. That is IN+ and IN- are intended to always be 180 degrees out of phase with respect to one another. In the scenario described in the previous sentence, the common-mode of the ADC input will be constant. The target common-mode value to achieve optimal performance with the AD7687 is Vref/2. With a common-mode of Vref/2, the user can access the full dynamic range of the AD7687. Any deviation from this value will result in a reduction of dynamic range due to the absolute input voltage range of any analog input with respect to ground.
Because of the architecture of the ADC, evaluation has shown that deviation of the common-mode above Vref/2 can quickly degrade the performance of the ADC and ADI can no longer guarantee the ADC performance specifications at these elevated common-mode values.
Thank you very much for your response!
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