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