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CDCM7005: CDCM7005

Amarnath Subramanian
Prodigy 185 points
Part Number: CDCM7005

HI,

We are using CDCM7005RGZT clock synchronizer in one of our project, In this we are using XLP73V153.600000I as an Voltage Controlled Oscillator, Which gets an Control Voltage from  CDCM7005 - CP_OUT pin.

As per datasheet it is understood that in default condition CP-OUT pin gives half the voltage of VCC_CP pin. We have given 3.3V in VCC_CP pin and we are expecting to get 1.65V from CP-OUT pin.

But we are getting 3V from CP-OUT pin, Can you please advice on this issue. We could also find there is a oscillation in clock in Khz range.

Hereby attaching the schematic for your reference.

Thank you

Regards,

Amarnath G

g.amarnath17@gmail.com

CLOCK SYNCHRONIZER.pdf

  • 0
    TI__Genius 16845 points
    Hi Amarnath,

    Please take a look at this post on the forum, it is similar to what you have descirbed: e2e.ti.com/.../2590263

    "This looks to me that the problem is the input impedance of the Vc pin of the VCXO is too low. As such, there is a serious leakage current when the charge pump is in the off state.
    There are couples of way to resolve this problem:
    1. Use a VCXO with higher Vc pin input impedance
    2. use a higher fpd (around 1MHz)
    3. use a higher charge pump current"

    Kind regards,
    Lane