®
CMOS ST-BUS™ FAMILY
MT8941
Advanced T1/CEPT Digital Trunk PLL
Features
•
•
Provides T1 clock at 1.544 MHz locked to an 8
kHz reference clock (frame pulse)
Provides CEPT clock at 2.048 MHz and ST-
BUS clock and timing signals locked to an
internal or external 8 kHz reference clock
Typical inherent output jitter (unfiltered)= 0.07
UI peak-to-peak
Typical jitter attenuation at: 10 Hz=23 dB,100
Hz=43 dB, 5 to 40 kHz
≥
64 dB
Jitter-free “FREE-RUN” mode
Uncommitted two-input NAND gate
Low power CMOS technology
ISSUE 5
July 1993
Ordering Information
MT8941AE
MT8941AP
24 Pin Plastic DIP
28 Pin PLCC
-40°C to +85°C
•
•
•
•
•
Description
The MT8941 is a dual digital phase-locked loop
providing the timing and synchronization signals for
the T1 or CEPT transmission links and the ST-BUS.
The first PLL provides the T1 clock (1.544 MHz)
synchronized to the input frame pulse at 8 kHz. The
timing signals for the CEPT transmission link and the
ST-BUS are provided by the second PLL locked to
an internal or an external 8 kHz frame pulse signal.
The MT8941 offers improved jitter performance over
the MT8940. The two devices also have some
functional differences, which are listed in the section
on “Differences between MT8941 and MT8940”.
Applications
•
•
Synchronization and timing control for T1
and CEPT digital trunk transmission links
ST- BUS clock and frame pulse source
F0i
DPLL #1
C12i
2:1 MUX
CVb
Variable
Clock
Control
CV
ENCV
MS0
MS1
MS2
MS3
C8Kb
Mode
Selection
Logic
Frame Pulse
Control
Input
Selector
4.096 MHz
Clock
Control
DPLL #2
Clock
Generator
Ai
Bi
2.048 MHz
Clock
Control
F0b
C4b
C4o
ENC4o
C16i
C2o
C2o
ENC2o
Yo
V
DD
V
SS
RST
Figure 1 - Functional Block Diagram
3-43
MITEL [ MITEL NETWORKS CORPORATION ]
