MT90870 Datasheet, PDF (18/86 Pages) Zarlink Semiconductor Inc – Flexible 12 k Digital Switch (F12kDX)

MT90870
Data Sheet
1.0 Bidirectional and Unidirectional Applications
The MT90870 has a maximum capacity of 12,288 input channels and 12,288 output channels. This is calculated
from the maximum number of streams and channels: 48 input streams (32 Backplane, 16 Local) at 16.384 Mb/s
and 48 output streams (32 Backplane, 16 Local) at 16.384 Mb/s.
One typical mode of operation is to separate the Backplane and Local sides, as shown in Figure 3 below.
BSTi0-31
32 streams
BACKPLANE
BSTo0-31
32 streams
LSTo0-15
16 streams
LSTi0-15
16 streams
LOCAL
MT90870
Figure 3 - 8,192 x 4,096 Channels (16 Mb/s), Bidirectional Switching
In this system setup, the chip has a capacity of 8,192 input channels and 8,192 output channels on the Backplane
side as well as 4,096 input channels and 4,096 output channels on the Local side. Note that some of the output
channels on one side can come from the other side, i.e., Backplane input to Local output switching.
Often a system design does not need to differentiate between Backplane and Local side, and merely needs
maximum switching capacity. In this case, the MT90870 can be used as shown in Figure 4 to give the full 12,288 x
12,288 channel capacity.
INPUT
BSTi0-31
32 streams
LSTi0-15
16 streams
BSTo0-31
32 streams
OUTPUT
LSTo0-15
16 streams
MT90870
Figure 4 - 12,288 x 12,288 Channels (16 Mb/s), Unidirectional Switching
In this system, the Backplane and Local inputs and outputs are combined and the switch appears as a 48 stream
input by 48 stream output switch. This style of operation is similar to older switch designs, such as the MT90826.
Note, in either configuration the Backplane may be operated in the 32 Mb/s Mode, providing 512 channels on each
of the 16 available input and output streams (BSTi0-15 and BSTo0-15) operating at a data-rate of 32.768 Mb/s, in
conjunction with the Local streams (LSTi0-15 and LSTo0-15) operated at 16.384 Mb/s. This allows data-rate
conversion between 32.768 Mb/s and 16.384 Mb/s without loss to the switching capacity.
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Zarlink Semiconductor Inc.