e421371 Datasheet, PDF (9/29 Pages) Fuji Electric – Fractional-N PLL Frequency Synthesizer

MB15F83UL
(2) Data Setting
• RF synthesizer Data Setting (Fractional-N)
The divide ratio can be calculated using the following equation :
fVCORF = NTOTAL × fosc÷R
NTOTAL = P × N + A + F / Q ← (A < N − 2, F < Q)
fVCORF : Output frequency of external voltage controlled oscillator (VCO)
NTOTAL : Total division ratio from prescaler input to the phase detector input
fosc
: Output frequency of the reference frequency oscillator
R
: Preset divide ratio of binary 7 bit reference counter (3 to 127)
P
: Preset divide ratio of modulus prescaler (16 fixed)
N
: Preset divide ratio of binary 10 bit programmable counter (18 to 1023)
A
: Preset divide ratio of binary 4 bit swallow counter (0 to 15)
F
: A numerator of fractional-N (0 to 15)
Q
: A denominator of fractional-N, modulo 13
• Binary 7-bit Programmable Reference Counter Data Setting (RF1 to RF7)
Divide ratio (R) RF7 RF6 RF5 RF4 RF3 RF2 RF1
3
0
0
0
0
0
1
1
4
0
0
0
0
1
0
0


52
0
1
1
0
1
0
0


127
1
1
1
1
1
1
1
Note : Divide ratio less than 3 is prohibited.
• Fractional-N incremant of the fractional accumulator Data Setting (F1 to F4)
Setting value(F) F4
F3
F2
F1
0
0
0
0
0
1
0
0
0
1
2
0
0
1
0





15
1
1
1
1
Note : F < Q
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