TMS320F280049: digital input for AIO

Hi Linda,

For best practices in digital/analog board design, it is best to separate or isolate digital and analog circuit blocks as far away as possible to avoid signal coupling.  In this case though, it will be a challenge since the AIO will still end up in the same part of the chip as the other analog channels so signal trace isolation may not be straightforward.

What would affe4ct ADC performance though is the slew rate of the switching AIO.  If application code would take care of the following then noise coupling issues will be greatly minimized.

  - AIO will only be used when no conversions are happening on the ADC

  - If above cannot be avoided, it will be best if the AIO will only be used for housekeeping purposes only (in application, the high/low logic state being driven to the AIO is only used as a flag - for instance if state of AIO is '1' then application will configure SOC0 to channel A1...etc)

  - Do not use AIO as a high speed input pin as doing so will introduce noise in the conversion.

Regards,

Joseph