1.3 Configuration for JESD204B Subclass 1 Clock Generation
The Si5386 can be used as a high-performance, fully-integrated JEDEC JESD204B jitter cleaner while eliminating the need for discrete
VCXO and loop filter components. The Si5386 supports JESD204B subclass 0 and subclass 1 clocking by providing both device clocks
(DCLK) and system reference clocks (SYSREF). The 12 clock outputs can be independently configured as device clocks or SYSREF
clocks to drive JESD204B ADCs, DACs, FPGAs, or other logic devices. The Si5386 will clock up to six JESD204B subclass 1 targets,
using six DCLK/SYSREF pairs. If SYSREF clocking is implemented in external logic, then the Si5386 can clock up to 12 JESD204B
targets. Not limited to JESD204B applications, each of the 12 outputs is individually configurable as a high performance output for
traditional clocking applications.
For applications which require adjustable static delay between the DCLK and SYSREF signals, the Si5386 supports up to four DCLK/
SYSREF pairs, each with independently adjustable delay. An example of an adjustable delay JESD204B frequency configuration is
shown in the following figure. In this case, the N0 divider determines the device clock frequencies while the N1-N4 dividers generate the
divided SYSREF used as the lower frequency frame clock. Each output N divider also includes a configurable delay (Δt) for controlling
deterministic latency. This example shows a configuration where all the device clocks are controlled by a single delay (Δt0) while the
SYSREF clocks each have their own independent delay (Δt1 –Δt4), though other combinations are also possible. The bidirectional
delay is programmable over ±8.6 ns in 68 ps steps. See
4.8 Static Output Skew Control
for more information on delay control. The
SYSREF clock is always periodic and can be controlled (on/off) without glitches by enabling or disabling its output through register
writes.
IN_SEL[1:0]
IN0
IN0b
IN1
IN1b
IN2
IN2b
IN3/FB_IN
IN3b/FB_INb
÷P
1
÷P
0
÷P
2
÷P
3
DSPLL
LPF
PD
÷M
÷N
1
÷N
2
÷N
3
÷N
4
OUT6b
VDDO6
OUT6
VDDO7
VDDO0
OUT0Ab
OUT0A
OUT0b
OUT0
÷R
6
÷R
0A
OUT7b
OUT7
÷R
7
OUT5b
VDDO5
OUT5
÷R
5
OUT1b
VDDO1
OUT1
VDDO2
÷R
1
OUT2b
OUT2
÷R
2
OUT8b
VDDO8
OUT8
÷R
8
OUT3b
VDDO3
OUT3
VDDO4
÷R
3
OUT4b
OUT4
÷R
4
VDDO9
OUT9b
OUT9
OUT9Ab
OUT9A
÷R
9
÷R
0
÷R
9A
Device
Clocks
4x SYSREF
÷N
0
÷5
t
0
t
1
t
2
t
3
t
4
Figure 1.1. Si5386 Block Diagram
Si5386 Rev. E Reference Manual • Functional Description
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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