®
ISO
2
-CMOS ST-BUS™ FAMILY
MT9173/74
Digital Subscriber Interface Circuit
with
RxSB
Digital Network Interface Circuit
with
RxSB
Features
•
•
•
•
•
•
•
•
•
•
Receive sync output pulse
Full duplex transmission over a single twisted
pair
Selectable 80 or 160 kbit/s line rate
Adaptive echo cancellation
Up to 3km (9173) and 4 km (9174) loop reach
ISDN compatible (2B+D) data format
Transparent modem capability
Frame synchronization and clock extraction
MITEL ST-BUS compatible
Low power (typically 50 mW), single 5V supply
ISSUE 2
March 1997
Ordering Information
MT9173AE
24 Pin Plastic DIP (300mil)
MT9173AN
24 Pin SSOP
MT9173AP
28 Pin PLCC
MT9174AE
24 Pin Plastic DIP (300 mil)
MT9174AN
24 Pin SSOP
MT9174AP
28 Pin PLCC
-40°C to
+
85°C
Description
The MT9173 (DSIC) and MT9174 (DNIC) are
functionally identical to the MT9171/72 except for the
addition of one feature. The MT9173/74 include a
digital output pin indicating the temporal position of
the received "SYNC" bit of the biphase transmission.
This feature is especially useful for systems such as
PCS wireless base station applications requiring
close synchronization between microcells.
The MT9173 and MT9174 are identical except for the
MT9173 having a shorter loop reach. The generic
"DNIC" will be used to reference both devices unless
otherwise noted. The MT9173/74 are fabricated in
Mitel’s ISO
2
-CMOS process.
Applications
•
•
•
•
•
T
DD
Digital PCS (DECT, CT2, PHS) base
stations requiring cell synchronization
Digital subscriber lines
High speed data transmission over twisted
wires
Digital PABX line cards and telephone sets
80 or 160 kbit/s single chip modem
DSTi/Di
CDSTi/
CDi
Transmit
Interface
Prescrambler
Scrambler
Differentially
Encoded Biphase
Transmitter
Transmit
Filter &
Line Driver
L
OUT
F0/CLD
C4/TCK
F0o/RCK
MS0
MS1
MS2
RegC
Control
Register
Transmit
Timing
V
Bias
Address
Echo Canceller
Error
Signal
Echo Estimate
—
DPLL
MUX
L
OUT
DIS
Master Clock
Phase Locked
Transmit/
Clock
Receive
Timing &
Control
Sync Detect
Status
Receive
Precan
∑
+
Receive
Filter
-1
+2
L
IN
OSC2
DSTo/Do
CDSTo/
CDo
RxSB
Receive
Interface
De-
Prescrambler
Descrambler
Differentially
Encoded Biphase
Receiver
OSC1
V
DD
V
SS
V
Bias
V
Ref
Figure 1 - Functional Block Diagram
9-137
MT9173/74
Preliminary Information
24 PIN PDIP/ SSOP
Figure 2 - Pin Connections
Pin Description
Pin #
Name
24
1
2
3
4,5,
6
7
8
28
2
3
4
5,7,
8
9
10
L
OUT
V
Bias
V
Ref
Line Out.
Transmit Signal output (Analog). Referenced to V
Bias
.
Internal Bias Voltage
output. Connect via 0.33
µF
decoupling capacitor to V
DD
.
Internal Reference Voltage
output. Connect via 0.33
µF
decoupling capacitor to V
DD
.
Description
MS2-MS0
Mode Select
inputs (Digital). The logic levels present on these pins select the various
operating modes for a particular application. See Table 1 for the operating modes.
RegC
RxSB
Regulator Control
output (Digital). A 512 kHz clock used for switch mode power
supplies. Unused in MAS/MOD mode and should be left open circuit.
Receive Sync Bit
output (Digital). In DN mode, this output is held high until receive
synchronization occurs (i.e., until the sync bit in Status Register =1). Once low,
indicating synchronized transmission, a high going pulse (6.24
µs
wide pulse @ 160
kb/s and 12.5
µs
wide @ 80 kb/s) indicates the temporal position of the receive
"SYNC" bit in the biphase line transmission. Inactive and low in MOD mode.
Frame Pulse/C-Channel Load
(Digital). In DN mode a 244 ns wide negative pulse
input for the MASTER indicating the start of the active channel times of the device.
Output for the SLAVE indicating the start of the active channel times of the device.
Output in MOD mode providing a pulse indicating the start of the C-channel.
Control/Data ST-BUS In/Control/Data In
(Digital). A 2.048 Mbit/s serial control &
signalling input in DN mode. In MOD mode this is a continuous bit stream at the bit
rate selected.
Control/Data ST-BUS Out/Control/Data Out
(Digital). A 2.048 Mbit/s serial control &
signalling output in DN mode. In MOD mode this is a continuous bit stream at the bit
rate selected.
Negative Power Supply
(0V).
9
11
F0/CLD
10
12
CDSTi/
CDi
CDSTo/
CDo
V
SS
11
13
12
13
14
14
15
16
DSTo/Do
Data ST-BUS Out/Data Out
(Digital). A 2.048 Mbit/s serial PCM/data output in DN
mode. In MOD mode this is a continuous bit stream at the bit rate selected.
DSTi/Di
Data ST-BUS In/Data In
(Digital). A 2.048 Mbit/s serial PCM/data input in DN mode.
In MOD mode this is a continuous bit stream at the bit rate selected.
9-138
CDSTi/CDi
CDSTo/CDo
VSS
DSTo/Do
DSTi/Di
F0o/RCK
NC
LOUT
VBias
VRef
MS2
MS1
MS0
RegC
RxSB
F0/CLD
CDSTi/CDi
CDSTo/CDo
VSS
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VDD
LIN
TEST
LOUT DIS
Precan
OSC1
NC
OSC2
C4/TCK
F0o/RCK
DSTi/Di
DSTo/Do
4
3
2
1
28
27
26
•
VRef
VBias
LOUT
NC
VDD
LIN
TEST
12
13
14
15
16
17
18
MS2
NC
MS1
MS0
RegC
RxSB
F0/CLD
5
6
7
8
9
10
11
25
24
23
22
21
20
19
NC
LOUT DIS
Precan
OSC1
OSC2
NC
C4/TCK
28 PIN PLCC
Preliminary Information
Functional Description
The MT9173 and MT9174 are multifunction devices
capable of providing high speed, full duplex digital
transmission at up to 160 kbit/s over a twisted wire
pair. They use adaptive echo-cancelling techniques
and transfer data in a format compatible to the ISDN
basic rate. Several modes of operation allow an easy
interface to digital telecommunication networks
including PCS wireless base stations, smart
telephone sets, workstations, data terminals and
computers. The device supports the 2B+D channel
format (two 64 kbit/s B-channels and one 16 kbit/s D-
channel) over two wires as recommended by the
CCITT. The line data is converted to and from the
ST-BUS format on the system side of the network to
allow for easy interfacing with other components
such as the S-interface device in an NT1
arrangement, or to digital PABX components.
Smart telephone sets with data and voice capability
can be easily implemented using the MT9173/74 as
a line interface. The device’s high bandwidth and
long loop length capability allows its use in a wide
variety of sets. This can be extended to provide full
data and voice capability to the private subscriber by
the installation of equipment in both the home and
central office or remote concentration equipment.
Within the subscriber equipment the MT9173/74
would terminate the line and encode/ decode the
data and voice for transmission while additional
electronics could provide interfaces for a standard
telephone set and any number of data ports
supporting standard data rates for such things as
computer communications and telemetry for remote
meter reading. Digital workstations with a high
degree of networking capability can be designed
using the DNIC for the line interface, offering up to
160 kbit/s data transmission over existing telephone
lines. The MT9173/74 could also be valuable within
existing computer networks for connecting a large
number of terminals to a computer or for
intercomputer links. With the DNIC, this can be
accomplished at up to 160 kbit/s at a very low cost
per line for terminal to computer links and in many
cases this bandwidth would be sufficient for
computer to computer links.
Figure 1 shows the block diagram of the MT9173/74.
The DNIC provides a bidirectional interface between
the DV (data/voice) port and a full duplex line
operating at 80 or 160 kbit/s over a single pair of
twisted wires. The DNIC has three serial ports. The
DV port (DSTi/Di, DSTo/Do), the CD (control/data)
port (CDSTi/CDi, CDSTo/CDo) and a line port (L
IN
,
L
OUT
). The data on the line is made up of information
from the DV and CD ports. The DNIC must combine
information received from both the DV and CD ports
MT9173/74
and put it onto the line. At the same time, the data
received from the line must be split into the various
channels and directed to the proper ports. The
usable data rates are 72 and 144 kbit/s as required
for the basic rate interface in ISDN. Full duplex
transmission is made possible through on board
adaptive echo cancellation.
The DNIC has various modes of operation which are
selected through the mode select pins MS0-2. The
two major modes of operation are the MODEM
(MOD) and DIGITAL NETWORK (DN) modes. MOD
mode is a transparent 80 or 160 kbit/s modem. In
DN mode the line carries the B and D channels
formatted for the ISDN at either 80 or 160 kbit/s. In
the DN mode the DV and CD ports are standard ST-
BUS and in MOD mode they are transparent serial
data streams at 80 or 160 kbit/s. Other modes
include: MASTER (MAS) or SLAVE (SLV) mode,
where the timebase and frame synchronization are
provided externally or are extracted from the line and
DUAL or SINGLE (SINGL) port modes, where both
the DV and CD ports are active or where the CD port
is inactive and all information is passed through the
DV port. For a detailed description of the modes see
“Operating Modes” section.
In DIGITAL NETWORK (DN) mode there are three
channels transferred by the DV and CD ports. They
are the B, C and D channels. The B1 and B2
channels each have a bandwidth of 64 kbit/s and are
used for carrying PCM encoded voice or data. These
channels are always transmitted and received
through the DV port (Figures 3, 4, 5, 6). The C-
channel, having a bandwidth of 64 kbit/s, provides a
means for the system to control the DNIC and for the
DNIC to pass status information back to the system.
The C-channel has a Housekeeping (HK) bit which is
the only bit of the C-channel transmitted and
received on the line. The 2B+D channel bits and the
HK bit are double-buffered. The D-channel can be
transmitted or received on the line with either an 8,
16 or 64 kbit/s bandwidth depending on the DNIC’s
mode of operation. Both the HK bit and the D-
channel can be used for end-to-end signalling or low
speed data transfer. In DUAL port mode the C and D
channels are accessed via the CD port (Figure 7)
while in SINGL port mode they are transferred
through the DV port (Figures 5, 6) along with the B1
and B2 channels.
9-141
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