Help for a line in voltage question.

[kostbill]

Hello. I am designing a system for audio processing.

The problem is I am not good at analog electronics. The manual of the IC I am using, is saying that:

"The ADC full-scale range is 1.0 VRMS at AVDD = 3.3 V. The full-scale range tracks linearly with analog supply voltage AVDD. To avoid distortions, it is important not to exceed the full-scale range."

I am totally lost here. What does it mean? 1 Vrms = squareroot(2)/2? So my maximum voltage must be 0.354 Volt? And after the ADC, again, the maximum voltage I am going to use in order to convert my integer values into floating point numbers, will be 0.354 again?

Thanks for any help.

 

[IanP]

For ac signal 1Vrms means only that the positive peak is at 1.41V and the negative peak is at -1.41V ..

Your ADC can work between GND (0V) and Vdd (3.3V) ..

Just imagine you set the reference (DC offset) for the 1Vrms signal at Vdd/2 = 1.65V ..
If you do this you’ll never exceed the ADC’s full scale range (1.41+1.41=2.8 --- full range=3.3) ..

See the attached drawing ..

IanP
:wink: