The DOUT/DRDY pin is a dual-function output. The pin functions as the digital data output and the ADC data-ready indication.
First, this pin is used with SCLK to read conversion and register data from the device. Conversion or register data are shifted out on DOUT/DRDY on the SCLK rising edge. DOUT/DRDY goes to a high-impedance state when CS is high.
Second, the DOUT/DRDY pin indicates availability of new conversion data. DOUT/DRDY transitions low at the same time that the DRDY pin goes low to indicate new conversion data are available. Both signals can be used to detect if new data are ready. However, because DOUT/DRDY is disabled when CS is high, use the dedicated DRDY pin when monitoring conversions on multiple devices on the SPI bus.