The output frequency can be calculated with
the following 2 formula's:
With formula 1 we can set the internal VCO frequency between 600 and 900 MHz. With formula 2 we set the output frequency.
The table below shows the calculated values:
Output frequency, Fout= .. MHz
Input clock frequency, Fclk_in= ..MHz
a1=
a2=
b1=
b2=
c1=
c2=
a1+b1/c1=
a2+b2/c2=
..
.
.
..
.
..
.
..
.
..
.
..
.
..
.
Once we have calculated the above values we can then fill the registers of the SI5351a according to the datasheet
and application note 619
REGISTER SETTINGS
The output frequency can be calculated with
the following 2 formula's:
Reg. nr.
Value
Function
Dec.
Hex.
Binary
3
Output enable control
15
PLL input source: xtal or ClkIn
16
CLK0 control
17
CLK1 control
18
CLK2 control
22
Integer/Fractional mode selection PLL A loop
23
Integer/Fractional mode selection PLL B loop
26
PLL A, VCO A setting
27
28
29
30
31
32
33
34
PLL B, VCO B setting
35
36
37
38
39
40
41
42
CLK0 divider
43
44
45
46
47
48
49
50
CLK1 divider
51
52
53
54
55
56
57
58
CLK2 divider
59
60
61
62
63
64
65
149
Spread spectrum settings
150
151
152
153
154
155
156
157
158
159
160
161
165
CLK 0 phase
166
CLK 1 phase
167
CLK 2 phase
183
Load capacitance
Once we have calculated the above values we can then fill the registers of the SI5351a according to the datasheet
and application note 619
CLK 1 ON
1 MHz
FREQUENCY
FREQ. STEP
PHASE DELAY
2 mA
DRIVE
OFF
INVERT
A
PLL
FREQUENCY CALCULATIONS
The output frequency can be calculated with
the following 2 formula's:
With formula 1 we can set the internal VCO frequency between 600 and 900 MHz. With formula 2 we set the output frequency.
The table below shows the calculated values:
Output frequency, Fout= .. MHz
Input clock frequency, Fclk_in= ..MHz
a1=
a2=
b1=
b2=
c1=
c2=
a1+b1/c1=
a2+b2/c2=
..
.
.
..
.
..
.
..
.
..
.
..
.
..
.
Once we have calculated the above values we can then fill the registers of the SI5351a according to the datasheet
and application note 619
CLK 2 ON
1 MHz
FREQUENCY
FREQ. STEP
PHASE DELAY
2 mA
DRIVE
OFF
INVERT
A
PLL
FREQUENCY CALCULATIONS
The output frequency can be calculated with
the following 2 formula's:
With formula 1 we can set the internal VCO frequency between 600 and 900 MHz. With formula 2 we set the output frequency.
The table below shows the calculated values:
Output frequency (Fout)=
Input clock frequency (Fclk_in)=
a1=
a2=
b1=
b2=
c1=
c2=
a1+b1/c1=
a2+b2/c2=
..
.
.
..
.
..
.
..
.
..
.
..
.
..
.
Once we have calculated the above values we can then fill the registers of the SI5351a according to the datasheet
and application note 619
SYSTEM SETTINGS
OUTPUT LEVEL
0 % center
SPREAD SPECTRUM
Spread Spectrum calculations
The output frequency can be calculated with
the following 2 formula's:
With formula 1 we can set the internal VCO frequency between 600 and 900 MHz. With formula 2 we set the output frequency.
The table below shows the calculated values:
spread spectrum= 0 % center
SSUDP=
SSUP=
SSDN=
SSDN_p1=
SSDN_p2=
SSDN_p3=
SSUP_p1=
SSUP_p2=
SSUP_p3=
Once we have calculated the above values we can then fill the registers of the SI5351a according to the datasheet
and application note 619
