XRT7250 Datasheet, PDF (1/463 Pages) Exar Corporation – DS3/E3 FRAMER IC

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XRT7250
MARCH 2001
DS3/E3 FRAMER IC
REV. 1.1.1
GENERAL DESCRIPTION
The XRT7250 DS3/E3 Framer IC is designed to ac-
cept “User Data” from the Terminal Equipment and in-
sert this data into the “payload” bit-fields within an
“outbound” DS3/E3 Data Stream. Further, the Framer
IC is also designed to receive an “inbound” DS3/E3
Data Stream (from the Remote Terminal Equipment)
and extract out the “User Data”.
The XRT7250 DS3/E3 Framer is designed to support
full-duplex data flow between Terminal Equipment
and an LIU (Line Interface Unit) IC. The Framer De-
vice 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 XRT7250 DS3/E3 Framer IC consists of four sec-
tions.
The Transmit Section, includes a Transmit Payload
Data Input Interface, a Transmit Overhead data Input
Interface Section, a Transmit HDLC Controller, a
Transmit E3/DS3 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 E3/DS3 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 Section consists of a large
number of "Reset-upon-Read" and "Read-Only" reg-
isters that contain cumulative and "one-second" sta-
tistics that reflect the performance/health of the Fram-
er 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.
• Interfaces to all Popular Microprocessors
• Integrated Framer Performance Monitor
• Available in a 100 Pin PQFP package
• Operating Temperature -40°C to +85°C
APPLICATIONS
• Interface to DS3 or E3 Networks
• CSU/DSU Equipment.
• PCM Test Equipment
• Fiber Optic Terminals
BLOCK DIAGRAM OF XRT7250
TxOHFrame
TxOHEnable
TxOH
TxOHClk
TxOHIns
TxOHInd
TxSer
TxNib[3:0]
TxInClk
TxNibClk
TxFrame
MOTO
D[7:0]
A[8:0]
Int
CS
Rd_DS
Wr_RW
Rdy_Dtck
Reset
ALE_AS
RxSer
RxNib[3:0]
RxOutClk
RxNibClk
RxFrame
RxOHFrame
RxOH
RxOHClk
RxOHEnable
Transmit Overhead
Input
Interface Block
Transmit
Payload Data
Input
Interface Block
Transmit DS3/E3
Framer Block
Microprocessor
Interface
Tx LAPD Buffer/
Controller
Rx LAPD Buffer/
Controller
Receive Payload
Data Output
Interface Block
Receive Overhead
Output
Interface Block
Receive DS3/E3
Framer Block
Transmit LIU
Interface
Block
TxPOS
TxNEG
TxLineClk
Receive LIU
Interface
Block
RxPOS
RxNEG
RxLineClk
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com