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CDCM7005: frequency variable range

mjae mjae
Prodigy 10 points
Part Number: CDCM7005
Other Parts Discussed in Thread: CDCE62005

Tool/software:

I would like to ask if it is possible to output 24.32MHz ~ 26.88MHz when the Ref Clock Input Range is 380KHz ~ 420KHz using CDCM7005.

The output clock is Ref clock * 64

And using CDCM7005, another frequency usage is when the Ref Clock input range is 12MHz ~ 15MHz, can Output clock 1 output 98.8MHz ~ 109.2MHz and Output clock 2 output 197.6MHz ~ 218.4MHz

That is, Output clock 1 output clock is Ref clock * 8. And Output clock 2 output clock is Ref clock * 16

  • 0
    TI__Mastermind 23330 points

    Mjae,

    This should be supported. Ensure that the low frequency inputs are square waves rather than sine waves.

    Thanks,

    Kadeem

  • 0 in reply to Kadeem Samuel
    Prodigy 10 points

    Thank you Kadeem

    The first PLL I selected is CDCE62005.

    When using CDCE62005, the Ref Clock Input Range only operates up to 390KHz ~ 406KHz.

    And every time I click VCO calibration, the output phase changes, so I asked if CDCM7005 is a problem.

    Please advise which VCO is suitable to choose when using the Ref Input Range of 380KHz ~ 420KHz and 12MHz ~ 15MHz in CDCM7005.

    Thank you

  • 0 in reply to mjae mjae
    TI__Mastermind 23330 points

    Mjae,

    CDCE62005 supports an input frequency as low as 40kHz. The phase of the output will change upon recalibration, as there is no input-output phase alignment in this device.

    The CDCM7005, on the other hand, does support this behavior:

    The VC(X)O input supports a maximum frequency of 2200MHz. The VC(X)O selected must support a wide tuning voltage range.

    For the first one (nominal 400kHz input) a VCXO frequency such as 204.8MHz should be suitable.

    For the second one (nominal 13.5MHz input, but it is not easy to find a VCXO frequency that this integer multiplies up to) a 224MHz VCXO may work, depending on the tuning range.

    Thanks,
    Kadeem