4.8 Static Output Skew Control
The Si5386 uses independently adjustable output N dividers (N0 - N4) to generate up to 5 unique frequencies to its 12 outputs through
the output crosspoint switch. By default all output clocks are aligned. Each N divider has an independently adjustable delay path (Δt0
– Δt4) associated with it. Each of these dividers is available for applications that require deterministic output delay configuration. This
is useful for PCB trace length mismatch compensation or for applications that require quadrature clock generation. Integer N dividers
allow a minimum step size of 67.8 ps while Fractional N dividers allow a min step size of 67.8/256 pf. An example of generating two
frequencies with unique configurable path delays of Δt2 and Δt3 is shown in the figure below.
÷N
0
t
0
÷N
1
t
1
÷N
2
t
2
÷N
3
t
3
÷N
4
t
4
OUT2b
VDDO2
OUT2
VDDO3
VDDO0
OUT0Ab
OUT0A
OUT0b
OUT0
÷R
2
÷R
0A
OUT3b
OUT3
÷R
3
OUT1b
VDDO1
OUT1
÷R
1
OUT5b
VDDO5
OUT5
VDDO6
÷R
5
OUT6b
OUT6
÷R
6
OUT4b
VDDO4
OUT4
÷R
4
OUT7b
VDDO7
OUT7
VDDO8
÷R
7
OUT8b
OUT8
÷R
8
VDDO9
OUT9b
OUT9
OUT9Ab
OUT9A
÷R
9
÷R
0
÷R
9A
Figure 4.4. Example of Independently-Configurable Path Delays
A Soft Reset of the device, SOFT_RST (0x001C[0] = 1), is required to latch in the new delay value(s). All delay values are restored
to their NVM values after POR, RSTb, or HARD_RST. Delay default values can be written to NVM, allowing a custom delay offset
configuration at power-up or after a Hard Reset. Two sets of registers control the static output to output skew: Nx_DELAY and
Nx_IODELAY_x. CBPro controls the setting of these registers based upon customer inputs. See the table below for the details of these
registers.
Table 4.17. Static Output Skew Control Registers
Register Name
Hex Address [Bit Field]
Function
N0_DELAY[15:0]
[ 0x035A[7:0], 0x0359[7:0] ]
2’s complement delay values ranging from -32,768 to
32,767. Delay time is Nx_DELAY/256 * 67.8 ps for a total
range of +- 8.67 ns. If the Nx divider is in integer mode then
the lower 8 bits of Nx_DELAY are ignored.
N1_DELAY[15:0]
[ 0x035C[7:0], 0x035B[7:0] ]
N2_DELAY[15:0]
[ 0x035E[7:0], 0x035D[7:0] ]
N3_DELAY[15:0]
[ 0x0360[7:0], 0x035F[7:0] ]
N4_DELAY[15:0]
[ 0x0362[7:0], 0x0361[7:0] ]
Si5386 Rev. E Reference Manual • Output Clocks
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 1.2 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • December 9, 2021
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