®
®
T1/ESF Framer Circuit (ACCUNET T1.5)
ISO-CMOS ST-BUS™ FAMILY
MT8977
Preliminary Information
Features
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•
•
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D3/D4 or ESF framing and SLC-96 compatible
Two frame elastic buffer with jitter tolerance
improved to 156 UI
Insertion and detection of A, B, C, D bits,
signalling freeze, optional debounce
Selectable B8ZS, jammed bit (ZCS) or no zero
code suppression
Yellow alarm and blue alarm signal capabilities
Bipolar violation count, F
T
error count, CRC
error count
Selectable robbed bit signalling
Frame and superframe sync. signals, Tx and Rx
AMI encoding and decoding
Per channel, overall, and remote loop around
Digital phase detector between T1 line and ST-
BUS
One uncommitted scan point and drive point
Pin compatible with MT8976 and MT8979
ST-BUS compatible
ISSUE 2
May 1995
Ordering Information
MT8977AC
28 Pin Ceramic DIP
MT8977AE
28 Pin Plastic DIP
MT8977AP
44 Pin PLCC
-40°C to 85°C
Description
The MT8977 is a variant of the MT8976 framer,
which has been enhanced to meet ACCUNET
®
T1.5
wander tolerance (138 UI).
The MT8977 meets ESF and D3/D4 formats, and is
compatible with SLC-96 systems.
Applications
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•
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DS1/ESF digital trunk interfaces
Computer to PBX interfaces (DMI and CPI)
High speed computer to computer data links
TxSF
C2i
F0i
RxSF
DSTo
DSTi
C1.5i
ST-BUS
Timing
Circuitry
2 Frame
Elastic Buffer
with Slip
Control
DS1
Link
Interface
2048-1544
Converter
RxFDLClk
RxFDL
RxA
Remote &
Digital
Loopbacks
RxB
TxA
TxB
TxFDLClk
TxFDL
RxD
Serial
Control
Interface
ABCD
Signalling RAM
E1.5i
Phase
Detector
DS1
Counter
Data
Interface
CSTi0
CSTi1
CSTo
XCtl
XSt
Control Logic
•
E8Ko
V
SS
V
DD
ACCUNET
®
T1.5 is a registered trademark of AT & T
Figure 1 - Functional Block Diagram
4-99
MITEL [ MITEL NETWORKS CORPORATION ]
