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CDCE62005: 0.1V minimum VIN

Taketo Sato
Genius 9915 points
Part Number: CDCE62005

Hello team,

VIN(VIN-V/IN) of Differential input mode is specified with 0.1V(min) and 1.3V(max).

Does this 0.1V mean 0.1Vpp which is from +/-0.025V swing around common voltage at pos side and -/+0.025V swing around common voltage at neg side?

I am using LVPECL AC couple input with internal termination with VBB=1.9V.

Best regards,

  • 0
    TI__Genius 9915 points
    1. Now I see the spec means "amplitude" so the min 0.1V means 0.2Vpp differential, correct?
    2. If input reference has small amplitude I think it makes jitter or phase noise worse. To avoid this, is below configuration which uses external termination with larger resistor values with using internal VBB fine for CDCE62005 to make input reference signal amplitude large and better jitter performance?
    3. min 1V/ns slew rate is required for PRI_REF input according to datasheet. If we meet the requirement with internal termination, shouldn't we do above external termination with large resistors?

    Best regards,

  • +1 in reply to Taketo Sato
    TI__Genius 11235 points

    Hi Sato,

    1) That's correct on your follow-up. VID = VIH-VIL. To get the peak-to-peak voltage, you would double the VID making the spec 0.2-2.6Vpp.

    2) As long as the input swing meets the spec requirements, the jitter performance should not be affected and therefore, I don't see a need for the resistors.

    3) If the requirement is met with internal, why use external? Internal is fine to use and large are not needed per #2.

    Regards,

    Jennifer

  • 0 in reply to Jennifer Bernal
    TI__Genius 9915 points

    Hello Jennifer-san,

    Thank you for your comments.

    I understand if input swing(amplitude and slew rate) meets minimum requirement, it doesn't affect jitter performance so much.

    Can the device support a use case of external termination resistors with using internal termination voltage from VBB pin like a image in my previous post?

    Best regards,

  • +1
    TI__Genius 11235 points

    Hi Sato, 

    Yes, the device could support external but the user should make sure that the internal terminations are disabled to not cause conflict.

    Regards,

    Jennifer