Exar
Corporation 48720 Kato Road, Fremont CA, 94538
(510) 668-7000
FAX (510) 668-7017
www.exar.com
á
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
OCTOBER 2003
REV. 1.2.1
GENERAL DESCRIPTION
The XRT72L50, single Channel DS3/E3 Framer IC is
designed to accept user data from the Terminal
Equipment and insert this data into the payload bit-
fields within an outbound DS3/E3 Data Stream. Fur-
ther, the Framer IC is also designed to receive an in-
bound DS3/E3 Data Stream from the Remote Termi-
nal Equipment and extract out the user data.
The XRT72L50 DS3/E3 Framer device is designed to
support full-duplex data flow between Terminal Equip-
ment and an LIU (Line Interface Unit) IC. The Framer
Device will transmit, receive and process data in the
DS3-C-bit Parity, DS3-M13, E3-ITU-T G.751 and E3-
ITU-T G.832 Framing Formats.
The XRT72L50 DS3/E3 Framer IC consists of a
Transmit section, Receiver section, Performance
Monitor Section and a Microprocessor interface.
The Transmit Section includes a Transmit Payload
Data Input Interface, a Transmit Overhead data Input
Interface Section, a Transmit HDLC Controller, a
Transmit DS3/E3 Framer block and a Transmit LIU In-
terface Block which permits the Terminal Equipment
to transmit data to a remote terminal.
The Receive Section consists of a Receive LIU Inter-
face, a Receive DS3/E3 Framer, a Receive HDLC
Controller, a Receive Payload Data Output Interface,
and a Receive Overhead Data Interface which allows
the local terminal equipment to receive data from re-
mote terminal equipment.
The Microprocessor Interface is used to configure the
Framer IC in different operating modes and monitor
the performance of the Framer.
The Performance Monitor Sections consist of a large
number of Reset-upon-Read and Read-Only regis-
ters that contain cumulative and one-second statistics
that reflect the performance/health of the Framer IC/
system.
FEATURES
Transmits, Receives and Processes data in the
DS3-C-bit Parity, DS3-M13, E3-ITU-T G.751 and
E3-ITU-T G.832 Framing Formats.
1 Channel HDLC Controller - Tx and Rx
Interfaces to all Popular Microprocessors
Integrated Framer Performance Monitor
Available in a 100 Pin PQFP package
3.3V Power Supply with 5V Tolerant I/O
Operating Temperature -40°C to +85°C
APPLICATIONS
Network Interface Units
CSU/DSU Equipment.
PCM Test Equipment
Fiber Optic Terminals
DS3/E3 Frame Relay Equipment
F
IGURE
1. B
LOCK
D
IAGRAM
OF
THE
XRT72L50
T3/E3 Transmit
Framer
T3 FEAC & Data
Link Controller
T3/E3 Receive
Framer
Performance
Monitor
Interrupt
Controller
TxOHInd
TxNibFrame
TxFrame
TxNibClk
TxLnClk
TxFrameRef
TxNib
TxSer
T3/E3
transmit
Input
RxClk
RxOHind
RxFrame
RxNib
RxSer
RxOutClk
T3/E3
Receive
Output
A[8:0]
D[7:0]
ALE_AS
WR_R/W
CS
RDY_DTCK
Reset
Int
MOTO
RD_DS
μ
P
Interface
TxLineClk
TxPOS
TxNEG
RxLineClk
RxPOS
RxNEG
ExtLOS
LIU
Interface/
Controller
TestMode
NibIntf
TxOHEnable
TxOHClk
TxOHFrame
TxAISEn
TxOH
TxOHIns
T3/E3
Transmit
Overhead
Interface
RxOHEnable
RxOHClk
RxOH
RxRed
RxOHFrame
RxOOF
T3/E3
Receive
Overhead
Interface
HDLC
controller
HDLC
controller
TRST