mt90870ag2 Zarlink Semiconductor, mt90870ag2 Datasheet - Page 41

• Manufacturer Part Number: mt90870ag2
• Description: Flexible 12 K Digital Switch F12kdx
• Manufacturer: Zarlink Semiconductor

5.0
For all data rates, the received serial data is converted to parallel format and stored sequentially in the data
memory. Each data memory location corresponds to an input stream and channel number. To provide constant
delay and maintain frame integrity, the MT90870 utilizes four pages of data memory. Consecutive frames are
written in turn to each page of memory. Reading is controlled to allow a channel data written in frame N to be read
during frame N+3.
A constant delay of three frames is applied to all switching paths irrespective of data-rate or channel number. See
Figure 16.
(32 Mb/s)
(16 Mb/s)
Data Delay Through the Switching Paths
(16 Mb/s)
(16 Mb/s)
(8 Mb/s)
(8 Mb/s)
(8 Mb/s)
(2 Mb/s)
(8 Mb/s)
(4 Mb/s)
BSTo1
BSTo1
LSTo1
LSTo1
LSTo1
BSTi0
BSTi0
BSTi0
LSTi0
LSTi0
FP8o
Figure 16 - Constant Switch Delay: Examples of Different Stream Rates and Routing
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CH
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Frame N
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Example showing Backplane to Backplane switching
Example showing Backplane to Local switching
Example showing Local to Local switching
Example showing Local to Backplane switching
Example showing 32 Mb/s mode, Backplane to Local switching
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Zarlink Semiconductor Inc.
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MT90870
Frames N+1 and N+2
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CH
CH
CH
Frame N+3
0
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0
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CH
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Frame N+4
0
0
0
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CH
CH
CH
CH
CH
CH
Data Sheet
0
0
0
0
0
0
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CH
1
1
1
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