Hi Cristian,
Sorry for the delay!
The EP version of this part is supported by our high reliability group (forum link: http://e2e.ti.com/support/applications/high_reliability/default.aspx), however, I will help you with this issue. Regarding your questions:
- The channel data read command must be issued each time data is read.
- For channel data read direct, you hold DIN either HIGH or LOW and start clocking data out. (The ADC will recognize this as the "channel data read direct command"). This does need to be somewhat "sync'd" with /DRDY because you will want to perform this "command" after /DRDY goes low and before it goes low again to prevent data corruption (The ADC will be updating data while you are still reading it out). The channel data read command does not need to be sync'd with /DRDY and may be better to use if you are not monitoring /DRDY.
Note: That when using channel data read direct, there is also requirement to toggle /CS or wait for the SPI interface to timeout, before you can send another command.
From page 31 of the datasheet:
Best regards,
Chris