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TMS320F28P550SJ: F28P55: Is Single-ended 3.3-V External Clock require CL?

Zane Wei
Intellectual 1825 points
Part Number: TMS320F28P550SJ


Tool/software:

Hi Team,

My customer is using F28P55, signal-ended OSC 25MHz,  Passive crystal OSC will need calculate CL, does signal-ended OSC need think of the internal CL? 15pf can work?

Best Regards,

Zane

  • +1
    TI__Mastermind 38620 points

    Hi Zane,

    CL is critical for external crystal as this will impact the accuracy and start up of the crystal.  In single-ended oscillator clocks, this is not critical but follow the oscillator manufacturer's specification just to be on the safe side.  Pin and pad capacitance of X1 is around 5pF for short PCB traces so seems like 10 to 15pF would be a good value to put in as CL to the oscillator's output.

    Regards,

    Joseph