MT8950 Mitel Networks Corporation, MT8950 Datasheet - Page 5

• Manufacturer Part Number: MT8950
• Description: ISO-CMOS ST-BUS FAMILY Data Codec
• Manufacturer: Mitel Networks Corporation

(Note: Waveforms shown are bipolar RZ equivalent of separate RZ/NRZ inputs)
† Note: The Level bit (b7) indicates the level (HIGH or LOW) of the input data in timeslot 31 of the current frame.
of seven frames types are possible as shown in
Figure 3. In frame type 7, the first five bits (b0 to b4)
are used to represent two transitions instead of the
normal first transition. Note that the data transitions
in Figure 3 are shown as a three level signal. A
positive transition indicates the beginning of one or
more continuous MARKs and a negative transition
indicates the beginning of one or more continuous
SPACEs.
#
1
2
3
4
5
6
7
Internal
Clock
#
1
2
3
4
5
6
7
No Pulse
2 Data Pulses (T=52 µs)
3 Data Pulses (T=52 µs)
1 Data Pulse
Violation Pulse
2 Data Pulses (T=104 µs)
(Timeslot 4 to 31)
2 Data Pulses (T=104 µs)
(Timeslot 0 to 3)
b7
1
1
1
1
1
1
1
-1
0
0
Description
b
4
b
Frame
b
1
1
3
1
b
b
2
0
b
2
2
1
b
0
3
3
4
4
b
4
b
5
3
b
b
2
4
b
b
6
1
3
b
b
0
2
Level
b
7
b
1
1/0
1/0
1/0
1/0
1/0
1/0
1/0
4
b
b7
b
0
3
8
b
2
Figure 3 - TEM Coding Scheme
Table 2. TEM Coding Summary
†
b
1
9
b
0
10
Frame Type
125 s
b6 b5
1
1
1
1
1
0
0
• • •
1
1
1
0
0
1
0
The decoder stage regenerates the original data
from the 8 bit TEM word. The absolute values of the
data signal in the present and previous frames as
given by b7(n) and b7(n-1) are EX-ORed and the
result in combination with the remaining bits of the
TEM word is used to reproduce the original data with
an accuracy of ± 3.906µs (see Table 2). Due to the
data speed restriction above 8 kbps, the second and
third transitions (if any) will be reproduced at
22
b
4
b
3
23
b
First Transition
2
b4 b3 b2 b1 b0
X X X X X
X X X X X
X X X X X
X X X X X
Y Y Y X X
X X X X X
b
1 1 1 1 1
0
1
24 25 26 27 28 29 30 31 0
b
0
1
b
4
b
2
3
b
b
4
2
b
b
3
1
3
b
b
2
0
ISO-CMOS
=11111
4
5
6
X X X X X
X X X X X
X X X X X = 0 to 31
X X X X X = 0 to 31
X X X X X > 00011 (3)
XX = 0 to 3
YYY = 0 to 7
b7
1
0
1
1
1
0
1
7
0
Notes
MT8950
10001 (17)
00100 (4)
Frame Type
b6
1
1
1
1
1
0
0
b5
1
1
1
0
0
1
0
6-7