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LMX2592: Output resolution

Gregory Duperon
Expert 7600 points
Part Number: LMX2592


For a desired output frequency between 99-111MHz, what's the best-case resolution I can achieve with LMX2592?

Can I achieve a resolution of 25kHz with LMX2592?

  • 0
    TI__Guru** 111060 points

    Hi Gregory,

    Assume there is no output divider and VCO pre-scalar, the resolution of a fractional-N PLL is equal to fpd/DEN. 

    In your case, given CHDIV=36, Pre-scalar = 2 and resolution = 25kHz at the output.

    resolution x CHDIV = fpd x pre-scalar / DEN.

    If you set fpd = 72MHz, then DEN=160. Changing NUM by 1 will change the output freq by 25kHz.