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ACS8527 Datasheet PDF : 22 Pages
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ACS8527 MUXPLL
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
DPLL Acquisition Bandwidth
the input becomes active again then the DPLL will
The ACS8527 DPLL has a preset acquisition bandwidth of continue to lock to the input, with little disturbance.
70 Hz.
DPLL Input Tracking (Locked) Bandwidth
Outputs
The ACS8527 DPPL has a preset tracking bandwidth of
35 Hz. This bandwidth setting corresponds to the -3 dB
jitter attenuation point on the ACS8527’s jitter transfer
characteristic.
The ACS8527 delivers four output signals on the following
ports: Two clocks, one each on outputs O1 and O2, and
two Sync signals, one each on output ports FrSync and
MFrSync. Outputs O1 and O2 are independent of each
other and are individually selectable. Output 01 is an
DPLL Damping Factor
The DPLL damping factor is 10, giving a PLL jitter transfer
peak gain of 0.06 dB.
LVDS compatible differential port (pins O1POS and
O1NEG). Output O2 (pin O2) and the Sync outputs are
TTL/CMOS compatible. The two Sync outputs, FrSync (8
kHz) and MFrSync (2 kHz), are derived from the DPLL.
Fast Activity Monitor
Anomalies on the selected clock have to be detected as
they occur and the PLL must be temporarily isolated until
the clock is once again pure. The phase locked loop itself
contains a fast activity monitor such that within
approximately two missing input clock cycles, the LOS
alarm on pin LOS_ALARM is raised and the DPLL is frozen
in Digital Holdover mode. With the DPLL in Digital
Holdover mode it is isolated from further disturbances. If
Output Frequency Selection
The frequencies available on the outputs can be selected
from a range of spot frequencies by hardware selection,
configuring the pins OP_FREQ1 [2:0], OP_FREQ2[2:0] and
SONSDH, which are read on reset.
Tables 5 and 6 show the hardware settings for selecting
from 11 output frequencies on outputs 01 and 02.
Table 5 Output 01 Frequency Selection by Hardware Configuration
O1_FREQ
SONSDHB Pin
2
1
0
0
0
0
X
0
0
0
1
1
0
1
0
X
0
1
1
X
1
0
0
X
1
0
1
X
1
1
0
X
1
1
1
X
Output Frequency/
MHz
0
34.368
44.736
19.44
25.92
38.88
51.84
77.76
155.52
Jitter Level (typ)
rms (ps) p-p (ns)
-
-
120
1
110
1
60
0.6
60
0.6
60
0.6
60
0.6
60
0.6
60
0.6
Revision 4.01/June 2006 © Semtech Corp.
Page 8
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