
Exar Corporation 48720 Kato Road, Fremont CA, 94538  (510) 668-7000  FAX (510) 668-7017  www.exar.com
XRT75R03D
EXAR DATA SHEET FORMAT TEMPLATES
MARCH 2006
REV. 1.0.4
GENERAL DESCRIPTION
The XRT75R03D is a three-channel fully integrated
Line Interface Unit (LIU) featuring EXAR’s R3
Technology (Reconfigurable, Relayless Redundancy)
with Jitter Attenuator for E3/DS3/STS-1 applications.
It
incorporates
3
independent
Receivers,
Transmitters and Jitter Attenuators in a single 128 pin
LQFP package.
Each
channel
of
the
XRT75R03D
can
be
independently configured to operate in the data rate,
E3 (34.368 MHz), DS3 (44.736 MHz) or STS-1 (51.84
MHz). Each transmitter can be turned off and tri-
stated for redundancy support or for conserving
power.
The XRT75R03D’s differential receiver provides high
noise interference margin and is able to receive the
data over 1000 feet of cable or with up to 12 dB of
cable attenuation.
The XRT75R03D incorporates an advanced crystal-
less jitter attenuator per channel that can be selected
either in the transmit or receive path. The jitter
attenuator performance meets the ETSI TBR-24 and
Bellcore GR-499 specifications.
The
XRT75R03D
provides
both
Serial
Microprocessor Interface as well as Hardware mode
for programming and control.
The XRT75R03D supports local, remote and digital
loop-backs. The device also has a built-in Pseudo
Random Binary Sequence (PRBS) generator and
detector with the ability to insert and detect single bit
error for diagnostic purposes.
FEATURES
RECEIVER:
 R3
Technology
(Reconfigurable,
Relayless
Redundancy)
 On chip Clock and Data Recovery circuit for high
input jitter tolerance
 Meets E3/DS3/STS-1 Jitter Tolerance Requirement
 Detects and Clears LOS as per G.775
 Receiver Monitor mode handles up to 20 dB flat
loss with 6 dB cable attenuation
 On chip B3ZS/HDB3 encoder and decoder that can
be either enabled or disabled
 On-chip clock synthesizer provides the appropriate
rate clock from a single 12.288 MHz Clock
 Provides low jitter output clock
TRANSMITTER:
 R3
Technology
(Reconfigurable,
Relayless
Redundancy)
 Compliant with Bellcore GR-499, GR-253 and ANSI
T1.102 Specification for transmit pulse
 Tri-state Transmit output capability for redundancy
applications
 Each Transmitter can be independently turned on
or off
 Transmitters provide Voltage Output Drive
JITTER ATTENUATOR:
 On chip advanced crystal-less Jitter Attenuator for
each channel
 Jitter Attenuator can be selected in Receive or
Transmit paths
 Meets ETSI TBR 24 Jitter Transfer Requirements
 Compliant with jitter transfer template outlined in
ITU G.751, G.752, G.755 and GR-499-CORE,1995
standards
 Jitter Attenuator can be disabled
CONTROL AND DIAGNOSTICS:
 5 wire Serial Microprocessor Interface for control
and configuration
 Supports optional internal Transmit driver
monitoring
 Hardware Mode for control and configuration
 Each channel supports Local, Remote and Digital
Loop-backs
 Single 3.3 V ± 5% power supply
 5 V Tolerant I/O
 Available in 128 pin LQFP
 - 40°C to 85°C Industrial Temperature Range
APPLICATIONS
 E3/DS3 Access Equipment
 STS1-SPE to DS3 De-Synchronizing
 DSLAMs
 Digital Cross Connect Systems
 CSU/DSU Equipment
 Routers
 Fiber Optic Terminals