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LMX2594: What will IncludedDivide be if channel divider is 2?

shen jie
Intellectual 275 points
Part Number: LMX2594


Tool/software:

Hi,

I use the two LMX2495 in my board, and want to sync the output clock(3932.16MHz) between them. As below figure.1 shown, my configuration is that Fosc =122.88MHz and Fout = 3932.16MHz。

 It conform to SYNC Category 1, so I set VCO_PHASE_SYNC=1. I find channel divider=2 but IncludedDivide=4 in the figure.3. My understanding is that IncludedDivide come from channel divider, so IncludedDivide must be less than channel divider. But now,  IncludedDivide are bigger than channel divider. My questions are:

1. Whether will this configuration work normally? 

2. N Divider(16) will turn red that the tip show that the minimum N divide for any modulator order is 28 , but I don't use MASH order function. Whether will this red warning impact my configuration?

Figure.1

Figure.2

Figure.3

Figure.4

Thanks in advance!

Best regards!

Jason

  • 0
    TI__Guru** 110830 points

    Hi Jason,

    includeddivide comes from SEG1, so IncludeDivide is either 4 or 6.

    Because IncludedDivide is 4, N-divider becomes 16 and therefore violating the min. N divider requirement,.

    you have to use a smaller fpd to make N-divider bigger. Since it is an integer channel, you can set MASH_ORDER  = 0. 

  • 0 in reply to Noel Fung
    Intellectual 275 points

    Hi，Neol:

     So the correct understanding as below figures shown, right?

    when VCO_PHASE_SYNC=0, feedback to PLL_N（=128） after VCO(Green line ) and output clock after 1/2(Blue line, also named SEG0).

    When VCO_PHASE_SYNC=1, feedback to PLL_N（=128） after Divider by 2 or 3 (Green line, also named SEG1  ) and output clock after 1/2(Blue line, also named SEG0).

    Thanks in advance!

    Best regards!

    Jason

  • 0 in reply to shen jie
    TI__Guru** 110830 points

    Hi Jason,

    That is correct.