CDCE913: M value calculation from ClockPro

Hello Shibatani,

Q1.

Your set frequency is 23.97602398MHz = 23,987,023.98Hz

ClockPro calculation frequency is 23.976023976024 MHz = 23,976,023.97024Hz

The idea is that the set frequency you had set is a repeating number and you rounded off the number at  nearest hundreth of Hz, calculate again and you will receive the same frequency as ClockPro but there is a slight error in ppm due to your rounding and ClockPro's exact calculated number. 

The ppm error is 0.0000166ppm = 0.0166ppb = 16.6ppt. At this inaccuracy this could be part to part variation of crystals and this setting works fine for your application.

Q2.

Here are the calculation as well as bit definitions of:

N = PLL1_xN[11:0] 12 bit register 0<N<4096

P = 4 – int(log2N / M)  = PLL1_0P[2:0] 3 bit register 0<=P<=7

Q = int(N' / M) = PLL1_xQ[5:0] 6 bit register 16<= Q<=63

R = N′ – M × Q = PLL1_xR[8:0] 9 bit register 0<=R<=511

These registers define values for P, Q, and R which have parameters that must be met, therefore determining if there is a good sequence for N/M ratio. This is why when trying to change M or N values you might cause unintentional F_vco ranges outside of parameters. Please use ClockPro Wizard for Setup generation if you are trying to calculate for a frequency combination.

Dear Sirs,

In regard to this post. please forget.

I had mistake that the value was rounded.

 24* 1000/1001 = 23.976023976024 should be  correct.

I 'm sorry.

But would you please advise my question in another post about changing fout on the fly?

Best Regards