LMK04906: How many frequencies can LMK04906B VCXO can generate?

Hello Shikhar,

The output frequency can be expressed in terms of the input frequency as Fout = Fin * N / (R * M), where N is the feedback divider, R is the reference divider, and M is the output divider. As long as N, R, and M are realizable values on the LMK04906, and VCO_Min <= Fin * N / R <= VCO_Max, any integer divide of the range of VCO_Min to VCO_Max could be realized.

Practically, there are additional limitations which constrain the frequency range:

• VCXOs are crystal oscillator devices, and their oscillation frequencies must be derived from some fundamental piezoelectric property of the crystal material. Consequently, there are only a few common VCXO frequencies, which greatly limits the total number of output frequencies.
• The phase noise performance of the PLL is partially a function of the phase detector frequency. If the phase detector frequency is low (i.e. if R and N are very large), the phase noise performance will be degraded. At higher phase detector frequencies, there are often only a handful of compatible VCO frequencies within range, again serving to limit the total number of possible output frequencies.

Your question is very broad, and I'm not sure if you're looking for more than just abstract formulas and general constraints. Is there a specific problem you want to solve with LMK04906?

Regards,

Well, I wanted to know how many VCXO associated pins are there in LMK04906. And how do they function?

For example, attached is the TICSPro screenshot of the clock outputs. It has 3 possible outputs with Oscin. However, 2 of the OScin outputs are muxed and can be provided by a Internal VCO. Is the Oscin outputs, same as VCXO outputs? How many of such outputs does the VCXO of LMK04906 has in the pin diagram. Moreover, how many distinct frequencies it can generate, is it 3 for example, if the clock outputs are 3 (with different divider at each output).

Regards,

Shikhar