ACS8510 View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'ACS8510' PDF : 69 Pages View PDF
ACS8510 Rev2.1 SETS
ADVANCED COMMUNICATIONS
Figure 5. Wander and Jitter Measured Transfer Characteristics
5
FINAL
0
-3
-5
-10
0.1 Hz
-15
0.3 Hz
0.5 Hz
1.0 Hz
-20
2.0 Hz
4.0 Hz
-25
8.0 Hz
17 Hz
-30
0.01
0.1
1
10
100
1000
Frequency (Hz)
1. ETSI 300 462-5, Section 9.1, requires that the short-
term phase error during switchover (i.e., Locked to Holdover
to Locked) be limited to an accumulation rate no greater
than 0.05 ppm during a 15 second interval.
3. ANSI Tin1.101-1994, Section 8.2.2, requires that the
phase variation be limited so that no more than 255 slips
(of 125 µs each) occur during the first day of Holdover.
This requires a frequency accuracy better than:
2. ETSI 300 462-5, Section 9.2, requires that the long-
term phase error in the Holdover mode should not
exceed
{(a1+a2)S+0.5bS2+c}
where
a1 = 50 ns/s (allowance for initial frequency offset)
a2 = 2000 ns/s (allowance for temperature variation)
b = 1.16x10-4 ns/s2 (allowance for ageing)
c = 120 ns (allowance for entry into Holdover mode).
((24x60x60)+(255x125µs))/(24x60x60) = 0.37 ppm
Temperature variation is not restricted, except to within
the normal bounds of 0 to 50 °C.
4. Telcordia GR.1244.CORE, Section 5.2., Table 4, shows
that an initial frequency offset of 50 ppb is permitted on
entering Holdover, whilst a drift over temperature of
280 ppb is allowed; an allowance of 40 ppb is permitted
for all other effects.
5. ITU G.822, Section 2.6, requires that the slip rate during
category(b) operation (interpreted as being applicable to
Holdover mode operation) be limited to less than 30 slips
(of 125 µs each) per hour
((((60 x 60)/30)+125µs)/(60x60)) = 1.042 ppm
Revision 2.00/September 2003 Semtech Corp.
19
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