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Si5332 12-Output Part
Output Pair
(Future Device)
Si5332 8-Output Part
Output Pair
Si5332 6-Output Part
Output Pair
Output Frequency
Variable for Solver
The Output Frequency
Group
OUT7
OUT5
F
3B
G
3
OUT8
F
3C
G
3
OUT9
OUT6
OUT4
F
4A
G
4
OUT10
OUT7
OUT5
F
5A
G
5
OUT11
F
5B
G
5
Table 6.3. Constraints for
hsdiv
and
id
Field Name
Value
Description
hsdivMinDiv
8
The minimum divide value that the HSDIV can support
hsdivMaxDiv
255
The maximum divide value that the HSDIV can support
idMinDiv
10
The minimum divide value that the ID can support
idMaxDiv
255
The maximum divide value that the ID can support
Each output frequency
Foutxy
is given by:
For the integer dividers (O0 – O4):
Foutxy
=
vcoFreq
hsdivj × Rxy
For the fractional dividers (N0, N1):
Foutxy
=
vcoFreq
Nxj × Rxy
An
hsdiv
or
N
divider is common for output frequencies grouped in a given Gx. Given these constraints, the solver must first choose a
PllRefFreq
that satisfies the constraints in
Table 6.4 Loop BW Options on page 20
. The search for
VcoFreq
can be broken down into
the following steps:
1. From the output frequency set, form a set of “M” non-equal frequencies. Group the (N-M) equal frequencies into the same “x” in
Foutxy grouping
2. Now form
M
C
2
groups of {M-2} output frequencies. Find the LCM of each group and find an integer “I” that can such that:
a.
vcoFreq
= I*LCM can meet the constraint for
vcoFreq
in Table 6.1 Constraints for PLL Reference Frequency and VCO Fre-
quency.
b. List the “L” groups that provide a legal
vcoFreq
, i.e., a
vcoFreq
that satisfies the condition in step a.
c. Choose the
vcoFreq
that has most number of performance critical clocks that do not need “spread spectrum” clocking as part
of the “M-2” output clocks.
Given that
vcoFreq
, calculate the fractional feedback divider as:
Mn
Md
=
vcoFreq
pllRefFreq
The
Mn/Md
fraction is represented in register fields IDPA_INTG, IDPA_RES and IDPA_DEN
IDPA_INTG
=
floor
(
128 × vcoFreq
pllRefFreq
)
IDPA_RES
IDPA_DEN
=
(
128 × vcoFreq
pllRefFreq
)
–
IDPA_INTG
As can be seen from the above equations, the ratio IDPA_RES/ IDPA_DEN will always be less than 1.
Si5332-AM1/2/3 Automotive Grade Device Reference Manual
Programming the Volatile Memory (Registers)
silabs.com
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