
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
(510) 668-7000
FAX (510) 668-7017
www.exar.com
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PRELIMINARY
XRT72L71
DS3 ATM UNI/CLEAR CHANNEL FRAMER
DECEMBER 2000
REV. P1.0.5
GENERAL DESCRIPTION
The XRT72L71 DS3 ATM User Network Interface
(UNI)/Clear-Channel Framer is designed to function
as either a DS3 ATM UNI or Clear channel framer.
For ATM UNI applications, this device provides the
ATM Physical Layer (Physical Medium Dependent
and Transmission Convergence sub-layers) interface
for both the public and private networks at DS3 rates.
For Clear-Channel framer applications, this device
supports the transmission and reception of “user da-
ta” via the DS3 payload bits.
The XRT72L71incorporates Receive, Transmit, Micro-
processor Interface, Performance Monitor, Test and Di-
agnostic and Line Interface Unit Scan Drive sections.
APPLICATIONS
Private User Network Interfaces
ATM Switches
ATM Concentrators
DSLAM Equipment
DS3 Frame Relay Equipment
FEATURES
Compliant with UTOPIA Level 1 and 2 with 8 or 16
Bit Interface Specification and supports UTOPIA
Bus speeds of up to 50 MHz
Contains on-chip 16 cell FIFO in both the Transmit
(TxFIFO) and Receive Directions (RxFIFO)
Contains on-chip 54 byte Transmit OAM Cell buffer
and a 108 byte Receive OAM cell buffer, for trans-
mission, reception and processing of OAM cells.
Supports PLCP or ATM Direct Mapping modes
Supports M13 and C-Bit Parity Framing Formats
Supports DS3 Clear Channel Framing Applications
Includes PRBS Generator and Receiver
Supports Local, Remote-Line, Cell, and PLCP
Loop-backs
Interfaces to 8 or 16 Bit wide Motorola and Intel μPs
Low power 3.3V, 5V input tolerant, CMOS
160 pin PQFP Package
3 and 4 Channel Version also Available
F
IGURE
1. XRT72L71 S
IMPLIFIED
B
LOCK
D
IAGRAM
WITH
S
YSTEM
I
NTERFACES
XRT73L00
RxUClav
DS3/E3 LIU
Tx
Rx
TPDATA
TNDATA
TCK
DMO
RLOS
RLOL
LLB
RLB
TAOS
TxLEV
ENCODIS
ReQDIS
RPOS
RNEG
RCLK1
UTOPIA BUS
Level 1 or 2
DS3
44.736 MHz
16
16
25, 33 or 50 MHz
Intel/Motorola
μ
P
Configuration, Control and Status Monitor
ATM Switch
D[15:0]
D[7:0]
A[8:0]
4
TxUClav
5
Address
5
XRT72L71
Address
ATM
Layer
Processor
Tx
UTOPIA
Interface
Tx
Cell
Processor
Tx
PLCP
Processor
Tx
DS3
Framer
Performance
Monitor
Microprocessor
Interface
FEAC
Processor
LAPD
Transceiver
Rx
UTOPIA
Interface
Rx
DS3
Framer
Rx
PLCP
Processor
Rx
Cell
Processor
LIU
Interface
Drive
and
Scan
75
coax
75
coax
TxPOS
TxNEG
TCK
DMO
RLOS
RLOL
LLOOP
RLOOP
TAOS
TxLEV
EncoDis
Req
RxPOS
RxNEG
RxLineClk
WR_RW
ALE_AS
RD_DS
RDY_DTCK