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F2808 Clock Source Options

Rick Nardone
Genius 10405 points

Hi,

   There are three options for input clock sources on the TMS32F2808:

  1.  3.3V External Oscillator
  2. 1.8V External Oscillator
  3. External Crystal with Internal Oscillator

   What are the recommendations/advice  for when to use each of the clock source options on the F2808? 

   Thanks,

     Rick

 

  • 0
    Expert 2220 points

    From my experience, here's what I think.  In all cases, I am assuming that the trace from the DSP to the oscillator is as-short-as-possible.

     

    Use 1.8V external oscillator for best results.  (Lower noise, lower power, and same accuracy compared to 3.3V external oscillator)

    Use 3.3V external oscillator if ...

    1. 1.8V version of your perferred oscillator is not available or
    2. if you don't want your 1.8V supply to feed anything other than your DSP.

    Use crystal oscillator if ...

    1. you don't care as much about frequency stability and accuracy or
    2. need the lowest cost or
    3. need the lowest power usage (e.g., battery powered device)

     

  • 0 in reply to quark
    TI__Genius 10405 points

    Thanks!!  This is exactly what I needed to know.

    - Rick