ACS8515REV2.1 Semtech Corporation, ACS8515REV2.1 Datasheet - Page 10

• Manufacturer Part Number: ACS8515REV2.1
• Description: Line Card Protection Switch for Sonet or SDH Network Elements
• Manufacturer: Semtech Corporation

Input Wander and Jitter Tolerance
Input Wander and Jitter Tolerance
Table 5. Input Reference Source Jitter Tolerance
Table 5. Input Reference Source Jitter Tolerance
PECL and LVDS ports support the spot clock
frequencies listed above plus 155.52 MHz. The
choice of PECL or LVDS compatibility is
programmed via the cnfg_differential_inputs
register.
Unused PECL/LVDS differential inputs should
be fixed with one input high (VDD) and the other
input low (GND), or set in LVDS mode and left
floating, in which case one input is internally
pulled high and the other low.
Input Wander and Jitter Tolerance
Input Wander and Jitter Tolerance
Input Wander and Jitter Tolerance
The ACS8515 is compliant to the requirements
of all relevant standards, principally ITU
Recommendation G.825, ANSI DS1.101-1994
and ETS 300 462-5 (1997).
All reference clock inputs have a tight frequency
tolerance but a generous jitter tolerance. Pull-
in, hold-in and pull-out ranges are specified for
each input port in Table 5. Minimum jitter
tolerance masks are specified in Figures 3 and
4, and Tables 6 and 7, respectively. The
ACS8515 will tolerate wander and jitter
components greater than those shown in Figure
Table 5. Input Reference Source Jitter Tolerance
Table 5. Input Reference Source Jitter Tolerance
Table 5. Input Reference Source Jitter Tolerance
Revision 2.01/December 2005 Semtech Corp.
ADVANCED COMMUNICATIONS
Notes for Table 5.
Notes for Table 5.
Notes for Table 5.
Notes for Table 5.
Notes for Table 5.
Note 1. The frequency acceptance and generation range will be +/-4.6 ppm around the required frequency when the
external crystal frequency accuracy is within a tolerance of +/- 4.6 ppm.
Note 2. The default acceptance range and generation range is +/- 9.2 ppm with an exact external crystal frequency
of 12.8 MHz. This range is also programmable from 0 to 80 ppm in 0.08 ppm steps.
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3 and Figure 4, up to a limit determined by a
combination of the apparent long-term
frequency offset caused by wander and the
eye-closure caused by jitter (the input source
will be rejected if the offset pushes the
frequency outside the hold-in range for long
enough to be detected, whilst the signal will
also be rejected if the eye closes sufficiently to
affect the signal purity). The ‘8klocking’ mode
should be engaged for high jitter tolerance
according to these masks.
All reference clock ports are monitored for
quality, including frequency offset and general
activity. Single short-term interruptions in
selected reference clocks may not cause
rearrangements, whilst longer interruptions, or
multiple, short-term interruptions, will cause
rearrangements, as will frequency offsets which
are sufficiently large or sufficiently long to cause
loss-of-lock in the phase-locked loop. The failed
reference source will be removed from the
priority table and declared as unserviceable,
until its perceived quality has been restored to
an acceptable level.
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ACS8515 Rev2.1 LC/P
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www.semtech.com
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