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Internal vs external oscillator?

Richard Cooke
Expert 1530 points
Other Parts Discussed in Thread: TMS320F28027F

HI,

Is there any gothcas to using the internal oscillator vs using an external crystal?  The LaunchPad schematic dated 4/2/2012 shows a 12MHz crystal connected to pins 45 & 46 but on the actual TMS320F28027F board I have doesn't use the external crystal.  My application will be mostly motor control so will I be OK using the internal clock?  Is it temperature sensitive?  My application won't be doing any complicated communication but it will be operating at times up to 45C - 60C.

Thanks,

Richard Cooke

  • 0
    TI__Guru 60865 points

    Hi Richard,

    At 60C the oscillator may drift up to around 1.5%.  

    If you integrate internal temperature sensor sampling into your ADC conversion code, then pass the results periodically to a TI provided function, the frequency drift can be compensated to within 1%.  

    If you need better accuracy than this, you will need to use an external crystal oscillator.