I am trying to develop an application on 21489 EZ-Kit. I've to use analog signals with very low amplitude (~100uV) to AD1939 codec. I've observed on the evaluation board that, even the input is unplugged from RCA connectors, DSP is getting some data from ADC (I measured it as ~3mV). But according to AD1939 data sheet SNR is 107dB. i.e. DSP should expect very small value with input unplugged (in the order of few uV).
Could any one please help me how to use 21489 EZ-Board for my application.