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LMX2492: Input impedance of OscIn, OscIn*, Fin and Fin* pin

AY
Prodigy 180 points
Part Number: LMX2492
Other Parts Discussed in Thread: LMX2430

Hi,

Can I get the information regarding the input impedance of OscIn, OscIn* Fin and Fin* pin as a function of frequency? Do you have some measurement data for that?

Thanks.

  • 0
    TI__Guru** 107390 points
    Hi AY,

    They are high impedance input.
    I am afraid we don't have the frequency sweep plot on these pins.
    We recommend terminate these pins with 50-ohms to ground or 100-ohm differential.
  • 0 in reply to Noel Fung
    Prodigy 180 points

    There are plots of the impedance of these pins in the other PLL datasheets, eg. LMX243x.

    Does it mean that you don't do any design verification measurement/characterisation at these pins for this LMX2492 chip?

     

  • 0 in reply to AY
    TI__Mastermind 28001 points
    Ay,

    Yes, we do some testing for these pins, but no we don't have input impedance for this device. We test for sensitivity and continuity.

    On the LMX2430, it is lower frequency, so this measurement was a little easier.

    So in general, it is intended to be high impedance, but don't try to do any sort of tuned impedance match; use a pad instead.

    Regards,
    Dean