CDCE925: Can not adjust frequency if clock input is from buffer

Hello,

Are you trying to use the part in VCXO mode, in XTAL mode, or in LVCMOS clock mode for the input buffer? If in VCXO mode, this will not work without an XTAL input.

Can you please provide the configuration that is being used for both conditions?
Thanks,

Kadeem

Hi Kadeem,

   They can not adjusted output frequency when input is clock buffer in LVCMOS mode. Is there any other reason.

925.TXT

Hello,

Is the series output resistor required by the 8L30110 clock buffer present?
Is the clock present and register changes are not changing the output frequency? If they write and read back, are the registers the same as the written values (in other words, is the device recognizing the I2C writes)?
Is the pass-through path for Y1 able to output a 24 MHz LVCMOS clock when Pdiv1 is set to 1?

Thanks,

Kadeem

Hi,

   The input is LVCMOS signal, dose it can adjust by VCXO. Customer's issue is that they can not use VCXO adjust output frequency if the input come from clock buffer LVCMOS signal. 

Do you have a solution to solve problem if can not use VCXO at LVCMOS input.

The problem as below，

The input 24Mhz clock is also mcu clock input, so the VCXO need have no influence for mcu clock. MCU need clock first power on for CDCE I2C set, so mcu can not use the CDCE925 output for clock input.

Hi，

  Do you have advice if customer need XTAL to VCXO and the MCU clock is not affected.

The input 24Mhz clock is also mcu clock input, so the VCXO need have no influence for mcu clock. MCU need clock first power on for CDCE I2C set, so mcu can not use the CDCE925 output for clock input.