DS21Q42
Enhanced QUAD T1 FRAMER
www.dalsemi.com
FEATURES
Four T1 DS1/ISDN–PRI/J1 framing
transceivers
All four framers are fully independent
Each of the four framers contain dual two–
frame elastic store slip buffers that can connect
to asynchronous backplanes up to 8.192 MHz
8–bit parallel control port that can be used
directly on either multiplexed or non–
multiplexed buses (Intel or Motorola)
Programmable output clocks for Fractional T1
Fully independent transmit and receive
functionality
Integral HDLC controller with 64-byte buffers
configurable for FDL or DS0 operation
Generates and detects in–band loop codes from
1 to 8 bits in length including CSU loop codes
Pin compatible with DS21Q44 E1 Enhanced
Quad E1 Framer
3.3V supply with 5V tolerant I/O; low power
CMOS
Available in 128–pin TQFP package
IEEE 1149.1 support
FUNCTIONAL DIAGRAM
Receive
Fram
er
Transm
it
Form
atter
FRAMER #0
FRAMER #1
FRAMER #2
FRAMER #3
Control Port
Elastic
Store
Elastic
Store
ACTUAL SIZE
QUAD
T1
FRAMER
ORDERING INFORMATION
DS21Q42T (0
0
C to 70
0
C)
DS21Q42TN (-40
0
C to +85
0
C)
DESCRIPTION
The DS21Q42 is an enhanced version of the DS21Q41B Quad T1 Framer. The DS21Q42 contains four
framers that are configured and read through a common microprocessor compatible parallel port. Each
framer consists of a receive framer, receive elastic store, transmit formatter and transmit elastic store. All
four framers in the DS21Q42 are totally independent, they do not share a common framing synchronizer.
Also the transmit and receive sides of each framer are totally independent. The dual two-frame elastic
stores contained in each of the four framers can be independently enabled and disabled as required. The
device fully meets all of the latest T1 specifications including ANSI T1.403–1995, ANSI T1.231–1993,
AT&T TR 62411 (12–90), AT&T TR54016, and ITU G.704 and G.706.
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031500
DALLAS [ DALLAS SEMICONDUCTOR ]
