XRT91L34IV-F View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT91L34IV-F' PDF : 38 Pages View PDF
XRT91L34
QUAD CHANNEL MULTIRATE STS-12/3/1 AND STM-4/1/0 SONET/SDH CDR
REV. 1.0.1
TABLE 3: CLOCK AND DATA RECOVERY UNIT PERFORMANCE
NAME
PARAMETER
MIN
TYP
MAX UNITS
REFDUTY
Reference clock duty cycle
40
60
%
REFTOL
Reference clock frequency tolerance2
-100
+100 ppm
TOLJIT
Input jitter tolerance with 1 MHz < f < 20 MHz PRBS pattern
0.3
0.4
UI
OCLKDUTY
Clock output duty cycle
45
55
%
Jitter specification is defined using a 12kHz to 0.4/1.3/5MHz LP-HP single-pole filter.
1These reference clock jitter limits are required for the outputs to meet SONET system level jitter requirements (<10 mUIrms).
2Required to meet SONET output frequency stability requirements.
2.2.1 Internal Clock and Data Recovery Disable
Optionally, each of the four internal CDR unit can be disabled and powered down when the channel is not in
use. Asserting the CDRDISn pin (where n = channel 0, 1, 2, or 3 ) "High" in Hardware Mode or setting
CDRDISn bit (where n = channel 0, 1, 2, or 3 ) in Host Mode, disables the internal Clock and Data Recovery
unit for that particular channel.
2.3 External Receive Loop Filter Capacitors
For STS12/STM4 and STS3/STM1 operation, use 0.47µF (or greater) non-polarized external loop filter
capacitors to achieve the required receiver jitter performance for each of the channels. For STS1/STM0
operation, use a minimum of 1.0µF non-polarized capacitors. If all 3 data rates STS12/STS3/STS1 are
required in an application, then use 1uF loop filter capacitors. They must be well isolated to prohibit noise
entering the CDR block and should be placed as close to the pins as possible. Figure 6 shows the pin
connections and external loop filter components. These four non-polarized capacitors should be of +/- 10%
tolerance. Use type X7R or X5R capacitors for improved stability over temperature.
FIGURE 6. EXTERNAL LOOP FILTERS
0.47uF
non-polarized
0.47uF
non-polarized
Channel 0 Loop Filter
External Capacitor
pin 109
pin 108
CAP0P
CAP0N
Channel 1 Loop Filter
External Capacitor
pin 103
pin 102
CAP1P
CAP1N
0.47uF
non-polarized
Use 1.0uF non-polarized
....
capacitors for
STS1/STM0 Operation
0.47uF
non-polarized
Channel 2 Loop Filter
External Capacitor
pin 59
pin 60
CAP2P
CAP2N
Channel 3 Loop Filter
External Capacitor
pin 53
Pin 54
CAP3P
CAP3N
16
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