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LMK1D1204: can i input a 500mhz single ended clock?

al8
Prodigy 40 points
Part Number: LMK1D1204

Can I input a 500mhz single ended clock if I reduce the voltage to less than 2V and bias the negative input to 1/2 the input range so it looks like a psudo differential?

The datasheet says single ended max input is only 250mhz.  Buf If the negative input is bias to 1/2 Input would that put me in the LVDS input max range of 2Ghz?

Does the chip know the difference between a true LVDS vs a 1/2 biased LVCMOS input?

Will this work for this chip?

  • 0
    TI__Genius 9250 points

    Hi Aaron,

    I see what you are trying to do. If we have half the swing of INP on INN that would give us better frequency range. Even your method above should work in theory on this device. 

    But we have not simulated this use case and the validation data is up to 250MHz for single ended case. 

    Chip doesn't know if its truly differential or single ended.  I would not recommend using it over 250MHz single ended conditions. 

    You could add a single ended to differential amplifier at the input of LMK1DXXX to avoid the unknown situation.

    Best,

    Asim

  • 0 in reply to Asim Khan
    Prodigy 40 points

    Hi Asim,

    Does TI have a part to convert the single ended to LVDS at 500Mhz?

    All the one's I've seen so far also tops out at 250Mhz or so. 

  • 0 in reply to al8
    TI__Genius 9250 points

    Hi Aaron,

    You can use LMX1204 for this frequency and set the desired VCM on it. It would be a little complicated part then the LMK1DXXX family else we can do the conversion as I suggested before.

    Best,

    Asim