xrt75r12 Exar Corporation, xrt75r12 Datasheet - Page 21

• Manufacturer Part Number: xrt75r12
• Description: Twelve Channel E3/ds3/sts-1 Line Interface Unit With Jitter
• Manufacturer: Exar Corporation

REV. 1.0.4
FUNCTIONAL DESCRIPTION
The XRT75R12 is a twelve channel fully integrated Line Interface Unit featuring EXAR’s R
(Reconfigurable, Relayless Redundancy) for E3/DS3/STS-1 applications.
independent Receivers, Transmitters and Jitter Attenuators in a single 420 Lead TBGA package. Each
channel can be independently programmed to support E3, DS-3 or STS-1 line rates using one input clock
reference of 12.288MHz in Single Frequency Mode (SFM). The LIU is responsible for providing the physical
connection between a line interface and an aggregate mapper or framing device. Along with the analog-to-
digital processing, the LIU offers monitoring and diagnostic features to help optimize network design
implementation. A key characteristic within the network topology is Automatic Protection Switching (APS).
EXAR’s proven expertise in providing redundany solutions has paved the way for R
Redundancy is used to introduce reliability and protection into network card design. The redundant card in
many cases is an exact replicate of the primary card, such that when a failure occurs the network processor
can automatically switch to the backup card. EXAR’s R
for 1:1 and 1+1 redundancy applications. Without relays and one Bill of Materials, EXAR offers multi-port,
integrated LIU solutions to assist high density aggregate applications and framing requirements with reliability.
The following section can be used as a reference for implementing R
line interface units.
A common network design that supports 1:1 or 1+1 redundancy consists of N primary cards along with N
backup cards that connect into a mid-plane or back-plane architecture without transformers installed on the
network cards. In addition to the network cards, the design has a line interface card with one source of
transformers, connectors, and protection components that are common to both network cards. With this
design, the bill of materials is reduced to the fewest amount of components. See
block diagram of a typical redundancy design.
F
1.0 R
1.1
IGURE
3
2. N
Network Architecture
TECHNOLOGY (RECONFIGURABLE, RELAYLESS REDUNDANCY)
Primary Line Card
Redundant Line Card
Framer/
Mapper
Framer/
Mapper
ETWORK
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
R
EDUNDANCY
LIU
LIU
Rx
Tx
Rx
Tx
0.01 F
0.01 F
0.01 F
0.01 F
31.6
31.6
31.6
31.6
A
RCHITECTURE
Plane
Plane
Back
18
Mid
or
3
technology has re-defined E3/DS-3/STS-1 LIU design
GND
3
Technology with EXAR’s world leading
1:1
1:1
The LIU incorporates 12
3
Figure
Technology.
Line Interface Card
2. for a simplified
XRT75R12
3
Technology