SI5328 Datasheet, PDF (20/70 Pages) Silicon Laboratories – ITU-T G.8262 SYNCHRONOUS ETHERNET JITTER-ATTENUATING CLOCK MULTIPLIER

Si5328
The phase of one output clock may be adjusted in
relation to the phase of the other output clock with
resolution that varies from 800 ps to 2.2 ns, depending
on the PLL divider settings. See Table 9 for instructions
on ensuring output-to-output alignment. The input to
output skew is not specified or controlled. The
DSPLLsim software utility determines the phase offset
resolution for a given input clock/clock multiplication
ratio combination. For system-level debugging, a
bypass mode is available which drives the output clock
directly from the input clock, bypassing the internal
DSPLL. The device is powered by a single 2.5 or 3.3 V
supply.
“AN775: Si5328 ITU-T G.8262 SyncE Compliance Test
Report” is a G.8262 test report using a 40 MHz Rakon
RTX7050A-109 TCXO. See “AN776: Using the Si5328
in a G.8262 Compliant SyncE Application” for a
discussion of how to select and best use a TCXO as
well as a list of other potential TCXO sources.
4.2. Further Documentation
Consult the Silicon Laboratories Si53xx Any Frequency
Precision Clock Family Reference Manual (FRM) for
detailed information about the Si5328 functions.
Additional design support is available from Silicon
Laboratories through your distributor.
4.1. External XAXB Reference
In order to achieve the levels of performance required
by G.8262, care must be exercised when selecting an
XA/XB reference. To meet the wander specifications in
G.8262, a TCXO or OCXO will be needed.
Silicon Laboratories has developed a PC-based
software utility called DSPLLsim to simplify device
configuration, including frequency planning and loop
bandwidth selection. The FRM and this utility can be
downloaded from http://www.silabs.com/timing.
Table 9. CKOUT_ALWAYS_ON and SQ_ICAL Truth Table
CKOUT_ALWAYS_ON
0
0
1
1
SQ_ICAL
0
1
0
1
Results
CKOUT OFF until after the first ICAL
CKOUT OFF until after the first successful
ICAL (i.e., when LOL is low)
CKOUT always ON, including during an ICAL
CKOUT always ON, including during an ICAL.
Use these settings to preserve output-to-output
skew
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Rev. 1.0