We're using the AD7606-6, with oversampling of 4 (samping frequency 51.2kHz). I see a delay of ~500us between input (at ADC pin) and sampled data (50Hz sine wave). We've debugged comprehensively and are 99% certain rest of the software works as expected. The only other possible reason is due to the digital filter in ADC. Unfortunately datasheet does not give much information on that, quoting only that it has 'linear phase response'.
Could the filter introduce such a large delay? Would it be possible to get more detailed information on the filter phase response?