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CDCM7005: VCC_CP/2 voltage tolerance and internal circuit

Part Number: CDCM7005

Hello,

VCC_CP is VCC of VC(X)O. When Charge Pump Preset to VCC_CP/2 is used, CP output will be VCC_CP x 0.5 voltage.

[Questions]

- What is the voltage tolerance of CP voltage when Charge Pump Preset to VCC_CP/2 used? I guess this voltage doesn't trim for more voltage accuracy.

- How to generate this voltage internally? Resister divider from VCC_CP to GND or any other way?

[VC(X)O question]

 - VC(X)O is voltage control oscillator. When VCC of VC(X)O is different but control voltage is mid of VCC, VC(X)O frequency is usually same or different?

Best regards,

Toshihiro Watanabe

  • Hello Toshihiro-san,

    The part allows for an external voltage to be applied to VCC_CP pin which can range from 2.3 V to 3.6 V. This voltage can then be divided by 2 using word 2 bit 3 SPI configuration. How the voltage is generated internally is described in "9.3.5 Charge Pump Preset to VCC_CP/2", there is an internal resistor divider to generate the VCC_CP/2.

    Regarding the external VC(X)O, this would depend on the particular part selected, frequency vs tuning voltage curves should be typically located on their datasheets. "When VCC of VC(X)O is different but control voltage is mid of VCC, VC(X)O frequency is usually same or different?" this may not always be true.

    Thanks,

    Vibhu