MT90863
Pin Description (continued)
128 MQFP
Pin#
84
144 BGA
Pin#
E12
Name
STo12
Description
Advance Information
Serial Output Streams 12 (5V Tolerant Three-state Output):
In
2Mb/s mode, this output has data rate of 2.048Mb/s with 32 channels
per stream. In Sub-rate Switching mode, this pin has data rate of
2.048Mb/s with 128 channels per stream for Sub-rate switching
application.
85-87
D13, E11, C13
STo13 - 15
Serial Output Streams 13 to 15 (5V Tolerant Three-state Outputs):
In 2Mb/s mode, these outputs have a data rate of 2.048Mb/s with 32
channels per stream.
Frame Alignment Timing
The Device Mode Selection (DMS) register allows
users to select three different frame alignment timing
modes. In ST-BUS modes, the master clock (C16i) is
always at 16.384 MHz. The frame pulse (F0i) input
accepts a negative frame pulse at 8kHz. The frame
pulse goes low at the frame boundary for 61ns. The
frame pulse output F0o provides a 244ns wide
negative frame pulse and the C4o output provides a
4.094MHz clock. These two signals are used to
support local switching applications. See Figure 4 for
the ST-BUS timings.
In CT Bus mode, the C4i/C8i pin accepts 8.192MHz
clock for the CT Bus frame pulse alignment. The F0i
is the CT bus frame pulse input. The CT frame pulse
goes low at the frame boundary for 122ns. See
Figure 5 for the CT Bus timing.
In HMVIP mode, the C4i/C8i pin accepts 4.096MHz
clock for the HMVIP frame pulse alignment. The F0i
is the HMVIP frame pulse input. The HMVIP frame
pulse goes low at the frame boundary for 244ns. See
Figure 6 for the HMVIP timing.
Table 1 describes the input timing requirements for
ST-BUS, CT Bus and HMVIP modes.
Device Overview
The Rate conversion Switch (MT90863) can switch
up to 2,048
×
512 channels while also providing a
rate conversion capability. It is designed to switch 64
kb/s PCM or N X 64 kb/s data between the
backplane and local interfaces. When the device is in
the sub-rate switching mode, 2-bit wide 16 kb/s data
channels can be switched within the device. The
device maintains frame integrity in data applications
and minimum throughput delay for voice application
on a per channel basis.
The backplane interface can operate at 2.048, 4.096
or 8.192 Mb/s, arranged in 125µs wide frames that
contain 32, 64 or 128 channels, respectively. A built-
in rate conversion circuit allows users to interface
between backplane interface and the local interface
which operates at 2.048 Mb/s or 8.192 Mb/s.
By using Mitel’s message mode capability, the
microprocessor can access input and output time-
slots on a per channel basis. This feature is useful
for transferring control and status information for
external circuits or other ST-Bus devices.
The frame offset calibration function allows users to
measure the frame offset delay for streams STio0 to
STio23. The offset calibration is activated by a frame
evaluation bit in the frame evaluation register. The
evaluation result is stored in the frame evaluation
registers and can be used to programme the input
offset delay for individual streams using internal
frame input offset registers.
Switching Configuration
The device has four operation modes for the
backplane interface and three operation modes for
the local interface. These modes can be
programmed via the Device Mode Selection (DMS)
register. Mode selections between the backplane
and local interfaces are independent. See Table 2
and Table 3 for the selection of various operation
modes via the programming of the DMS register.
Functional Description
A functional Block Diagram of the MT90863 is shown
in Figure 1. One end of the MT90863 is used to
interface with backplane applications, such as
HMVIP or H.100 environments, while the other end
supports the local switching environments.
6
MITEL [ MITEL NETWORKS CORPORATION ]
