Hi Gerald,
Welcome to the TI E2E Forums!
[quote user="Gerald Faulhaber"]
In general, it is save to trigger always on the falling edge of the DRDY and then start SPI communication?
Or are there situations where DRDY stays low (no falling edge) and does not toggle?
[/quote]
In general, when the ADC is converting, DRDY will be toggling. If you read the data or send other commands, DRDY will return HIGH. If you do not read the ADC data before the next conversion completes, then DRDY will create a short pulse to indicate new data. Sending/triggering SPI commands after a DRDY falling edge should be okay.
Regarding the SDATAC timing, I don't think you need to add a delay. If you want to be safe, use the same delay as the RDATAC command. I'll see if I can find out more information about this.
Regards,
Chris