Input level ADAU1701

Hi Vincent,

The decibel is a unit-less logarithmic ratio, so I'm not sure what you're referring to when you reference it to 0.707 VRMS. Perhaps you mean dBu? dBu is also called "dB unloaded", or dB(0.775 VRMS), which represents a 600 Ω load dissipating 0 dBm (1 mW). Wikipedia includes a very nice description of how decibels are commonly used for absolute measurements: http://en.wikipedia.org/wiki/Decibel#Absolute_measurements

In any case, the input range of the ADAU1701 is variable, depending on the voltage-to-current resistors you choose to place at the ADC inputs. More information is available in the datasheet here: http://www.analog.com/static/imported-files/data_sheets/ADAU1701.pdf

Here is an excerpt from the datasheet explaining the setting of the ADC input range:

If your input exceeds the full-scale input voltage range of the ADCs (as configured by the input resistors), the audio will clip, creating distortion.