2 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
The XRT79L72 is a two channel, ATM UNI/PPP
Physical Layer Processor with integrated DS3/E3
framing controllers and Line Interface Units with Jitter
Attenuators that are designed to support ATM direct
mapping and cell delineation as well as PPP mapping
and Frame processing. For ATM UNI applications,
this device provides the ATM Physical Layer (Physi-
cal Medium Dependent and Transmission Conver-
gence sub-layers) interface for the public and private
networks at DS3/E3 rates. For Clear-Channel Framer
applications, this device supports the transmission
and reception of “user data” via the DS3/E3 payload.
The XRT79L72 includes DS3/E3 Framing, Line Inter-
face Unit with Jitter Attenuator that supports mapping of
ATM or HDLC framed data. A flexible parallel micropro-
cessor interface is provided for configuration and con-
trol. Industry standard UTOPIA II and POS-PHY inter-
face are also provided.
• Integrated T3/E3 Line Interface Unit
• Integrated Jitter Attenuator that can be selected
either in Receive or Transmit path
• Flexible integrated Clock Multiplier that takes single
frequency clock and generates either DS3 or E3
• 8/16 bit UTOPIA Level I and II and PPP Multi-PHY
Interface operating at 25, 33 or 50 MHz.
• HDLC Controller that provides the mapping/extrac-
tion of either bit or byte mapped encapsulated
packet from DS3/E3 Frame.
• Contains on-chip 16 cell FIFO (configurable in
depths of 4, 8, 12 or 16 cells), in both the Transmit
(TxFIFO) and Receive Directions (RxFIFO)
• Contains on-chip 54 byte Transmit and Receive
OAM Cell Buffer for transmission, reception and
processing of OAM Cells
• Supports ATM cell or PPP Packet Mapping
• Supports M13 and C-Bit Parity Framing Formats
• Supports DS3/E3 Clear-Channel Framing.
• Includes PRBS Generator and Receiver
• Supports Line, Cell, and PLCP Loop-backs
• Interfaces to 8 Bit wide Intel, Motorola or PowerPC
• Low power 3.3V, 5V Input Tolerant, CMOS
• Available in 456 Lead PBGA Package
• JTAG Interface
LINE INTERFACE UNIT
• On chip Clock and Data Recovery circuit for high
input jitter tolerance
• Meets E3/DS3 Jitter Tolerance Requirements
• Detects and Clears LOS as per G.775.
• Receiver Monitor mode handles up to 20 dB flat
loss with 6 dB cable attenuation
• Compliant with jitter transfer template outlined in
ITU G.751, G.752, G.755 and GR-499-CORE,1995
• Meets ETSI TBR 24 and GR-499 Jitter Transfer
• 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
• On chip advanced crystal-less Jitter Attenuator
• Jitter Attenuator can be selected in Receive or
• 16 or 32 bits selectable FIFO size
• Meets the Jitter and Wander specifications
described in T1.105.03b,ETSI TBR-24, Bellcore
GR-253 and GR-499 standards
• Jitter Attenuator can be disabled
• Maximum power consumption 1.7W
• DS3 framer supports both M13 and C-bit parity.
• DS3 framer meets ANSI T1.107 and T1.404 stan-
• Detects OOF,LOF,AIS,RDI/FERF alarms.
• Generation and Insertion of FEBE on received par-
ity errors supported.
• Automatic insertion of RDI/FERF on alarm status.
• E3 framer meets G.832,G.751 standards.
• Framers can be bypassed.
ATM/PPP PROTOCOL PROCESSOR
TRANSMIT CELL PROCESSING
• Extracts ATM cells
• Supports ATM cell payload scrambling
• Maps ATM cells into E3 or DS3 frame
• PLCP frame and mapping of ATM cell streams
RECEIVE CELL PROCESSING
• Extraction of ATM cells from PLCP frame or directly
from E3 or DS3 frame
• Termination of PLCP frame
• Supports payload cell de-scrambling
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com