
Exar
Coporation 48720 Kato Road, Fremont CA, 94538
(510) 668-7000
FAX (510) 668-7200
www.exar.com
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PRELIMINARY
XRT7245
DS3 UNI FOR ATM
DECEMBER 1999
REV. 1.03
GENERAL DESCRIPTION
The XRT7245 DS3 ATM User Network Interface
(UNI) device is designed to provide the ATM Physical
Layer (Physical Medium Dependent and Transmis-
sion Convergence sub-layers) interface for the public
and private networks at DS3 rates. This device pro-
vides full-duplex data flow between two ATM Layer
devices (e.g., ATM Switching equipment) and/or ATM
Adaptation Layer (AAL) devices; over a DS3 Transport
Medium.
The XRT7245 DS3 UNI for ATM incorporates Receive,
Transmit, Microprocessor Interface, Performance Moni-
tor, Test and Diagnostic and Line Interface Unit Scan
Drive functional sections.
FEATURES
Compliant with UTOPIA Level 1and 2, 8 or 16 Bit,
Interface Specification and supports UTOPIA Bus
operating at 25, 33 or 50 MHz
Contains on-chip 16 cell FIFO (configurable in
depths of4, 8, 12 or 16 cells), in the transmit Direc-
tion (TxFIFO)
Contains on-chip Receive OAM Cell Buffer for
reception, filtering and processing of selected User
and OAM Cells
Supports PLCP or ATM Direct Mapping modes
Supports M13 and C-Bit Parity Framing Formats
Supports Line, Cell, and PLCP Loop-backs
Interfaces to 8 or 16 Bit wide Motorola and Intel μPs
and μCs
Available in 160 pin PQFP Package
APPLICATIONS
Private User Network Interfaces
ATM Switches
ATM Routers and Bridges
ATM Concentrators
F
IGURE
1. B
LOCK
D
IAGRAM
OF
THE
XRT7245 DS3 UNI IC
Microprocessor Interface
(Programmable
Registers and Interrupt
Block)
Line I/F Drive and Scan
Framer
Transmitter
Receiver
Receive
DS3
Framer
Performance
Monitor
Transmit
PLCP
Processor
Transmit Cell
Processor
Tx Utopia
Interface
Receive
PLCP
Processor
Receive Cell
Processor
Rx Utopia
Interface
A[8:0]
WrB_RW
RdB_DS
CSB*
ALE_AS
Reset
IntB*
D[15:0]
Width16
MOTO/Intel*
Rdy_Dtck
TxPOS
TxNEG
TxFrame
TxOHClk
TxLineClk
TxAISEn
TxFrameRef
TxInClk
TxOHIns
TxOH
TxPFrame
8kRef
StuffCtl
TxPOHFrame
TxPOH
TxPOHClk
TxCellTxed
TxGFCClk
TxGFCMSB
TxGFC
TxClk
TxData[15:0]
TxPrty
TxSoC
TxEnB
TxClav/TFullB
TxAddr[4:0]
RxLineClk
RxNEG
RxPOS
RLOS
RxAIS
RxOHClk
RxOH[7:0]
RxLOS
RxFrame
RxOOF
RxPOHClk
RxPOH
RxPFrame
RxPLOF
RxPOOF
RxPOHFrame
RxCellRxed
RxGFCClk
RxGFCMSB
RxGFC
RFClk
RxEnB
RxPrty
RxData[15:0]
RxSoC
RxClav/RxEmpty
RxAddr[4:0]
Transmit
DS3
Test and Diagnostic
FEAC
Processor
LAPD
Transceiver