CDC7005 - 160 MHz generation

Hi Ayn,

could you please specify if the 160MHz is applied to the REF_IN pin or to the VCXO pins?

The max REF_IN frquency is 130MHz,while the max VCXO frequency is 800MHz.

thanks and best regards

Leandro

160 MHz is applied to  VCXO pin.  As you mentioned REF_IN does not have that capability.

From the Data Sheet: 

The programmable predividers M and N give a high flexibility to the frequency ratio of the reference clock to VCXO: VCXO_IN/REF_IN = (NxP)/M.

 So, how do we set up these M, N, and P. I don’t see that anywhere in datasheet but I assume generating 160 MHz out of 240 MHz should be possible using these parameters.

Hi Ayn,

I need to know what is your REF_IN as well. In any case if you use a 160MHz at VCXO pin, you can only have at the output either the same frequency (160M) or a submultiple of it. The division ratios for the CDC7005 are 2,4,8,16.

Regards,

Leandro

Leandro,

It is 240 MHz.

How do we generate 160 MHz our of this?

What you mentioned tells me that it is impossible since these are only integer dividers that cannot generate 160 MHz that we need.  

Datasheet says that the programmable predividers M, N, and P can be set to get VCXO_IN/REF_IN = (NxP)/M. How do we set up these M, N, and P. I don’t see that anywhere in datasheet but I assume generating 160 MHz out of 240 MHz should be possible using these parameters.

regards

Hi Ayn,

the CDC7005 cannot handle 240MHz at the REF_IN pin. Do you have the chance to use rather a 120MHz signal at PRI_REF?

If this is the case, You need to set P=1, N=4 and M=3 in order to get 160MHz outputs.

If this is not the case, do you have any other clock frequency below than 180MHz (this is the max REF_IN frequency, I wrote a typo in some previous post) on your board

Regards,

Leandro