ADAU1761 - Maximum value for Digital Input / Output

Hello Vincent,

By definition, full-scale audio runs in the range from -1 to +0.99999 as shown below, This is maximum ("0 dB") level for the ADCs, the DACs, and any I2S audio.

Inside most SigmaDSPs, your available range is -16 to +15.9999 (the ADAU145x is the exception, it handles from -128 to +127.9999). Thus, you can go ahead and scale (multiply) your input accordingly. If for example you multiply your ADC signal by five, you have from -5 to +4.9999. This added range is meant for headroom, thus ideally would not be used for audio -- but it's perfectly valid in your application.

Before outputting the signal on a DAC or I2S link, you'll need to divide it back to the -1 -- +1 range (in other words, multiply by the reciprocal of the factor you're using after the ADC). DSPs are multiply-and-add machines, so multiplying is a lot easier than dividing,

Best regards,

Bob

I actually wanted to pass a signal through Digitial I/O to save some multiplication blocs (and division blocs) that actually cause problems in my design for uC integration.

I will therefore find another solution.

Thanks for your answer

Vincent