Problem with ADC AD7980

Dear Madam (Sir), there is a problem with ADC AD7980. It is impossible to calculate (take data). ADC connection is accordiance with the datasheets:

- SDI connected with VIO, 3,3 volts;

- REF 5 volts;

- VDD 2,5 volts;

CNV impulse is about 100 us. After that I take of ADC. The high level of voltage becomes after the first front of CNV impulse through =230ns. The low level of voltage becomes on SDO with the first SCK impulse. Thus there is no data of ADC. The same is on the all ADC this seria.

What would you like to recommend in such a case?

Thanks,