XRT82D20
SINGLE CHANNEL E1 LINE INTERFACE UNIT
AUGUST 2006
REV. 1.0.8
GENERAL DESCRIPTION
The XRT82D20 is a fully integrated, single channel,
Line Interface Unit (Transceiver) for 75
Ω
or 120
Ω
E1
(2.048 Mbps) applications. The LIU consists of a
receiver with adaptive data slicer for accurate data
and clock recovery and a transmitter which accepts
either single or dual-rail digital inputs for signal
transmission to the line using a low- impedance
differential line driver. The LIU also includes a crystal-
less jitter attenuator for clock and data smoothing
which, depending on system requirements, can be
selected in either the transmit or receive path.
Coupling the XRT82D20 to the line requires
transformers on both the Receiver and Transmitter
sides, and supports both 120
Ω
balanced and 75
Ω
unbalanced interfaces.
The receiver can be
capacitive coupled to for cost reduction
FEATURES
•
Clock Recovery and Selectable Crystal-less Jitter
attenuator
•
Compliant with ETS300166 Return Loss
•
Compliant with the ITU-T G.823 Jitter Tolerance
Requirements
•
Remote, Local and Digital Loop backs
•
Declares and Clears LOS per ITU-T G.775
•
Logic Inputs accept either 3.3V or 5.0V levels
•
- 40
0
C to 85
0
C Temperature Range
•
Low Power Dissipation; 145mW with 120
Ω
or
160mW with 75
Ω
typical
•
+3.3V or +5V Supply Operation
•
Pin Compatible with the XRT7288
APPLICATIONS
•
Complete E1 (CEPT) line interface unit
•
Generates transmit output pulses that are
compliant with the ITU-T G.703 Pulse Template for
2.048Mbps (E1) rates
•
On-Chip Pulse Shaping for both 75
Ω
and 120
Ω
Line Drivers
•
PDH Multiplexers
•
SDH Multiplexers
•
Digital Cross-Connect Systems
•
DECT (Digital European Cordless Telephone) Base
Stations
•
CSU/DSU Equipment
•
Test Equipment
F
IGURE
1. B
LOCK
D
IAGRAM OF THE
XRT82D20
TClk
TPOS
TNEG
TTIP
HDB3
Encoder
MUX
Tx Pulse
Shaper
Line
Driver
TRing
Jitter Attenuator
Digital
Loopback
Remote
Loopback
Data &
Timing
Recovery
MUX
Local
Loopback
LOS
Detect
RLOS
RClk
RPOS
RNEG
HDB3
Decoder
Data
Slicer
Peak
Detector
RTIP
RRing
Timing
Generator
MClk
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
EXAR [ EXAR CORPORATION ]
