I am wondering about the valid range of the external reference Voltage that can be applied to the AD9240’s VREF . The only limitation I could find was in the absolute maximum value section of the datasheet but I doubt that every VREF value applied between –0.3V and AVDD +0.3V will give me a usable result.
Am I overlooking something or is this range not specified? If so, is there a rule of thumb for that? Of course, except that the error of the ADC is constant with the supply voltage and therefore the SNR is decreasing with a lower reference voltage.