MT90870 Zarlink Semiconductor, Inc., MT90870 Datasheet - Page 30

• Manufacturer Part Number: MT90870
• Description: Flexible 12k Digital Switch (F12kDX)
• Manufacturer: Zarlink Semiconductor, Inc.

MT90870
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 15.
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(32Mb/s)
(16Mb/s)
(16Mb/s)
(16Mb/s)
(8Mb/s)
(8Mb/s)
(8Mb/s)
(2Mb/s)
(8Mb/s)
(4Mb/s)
BSTo1
LSTo1
LSTo1
BSTo1
LSTo1
BSTi0
BSTi0
BSTi0
LSTi0
LSTi0
FP8o
Data delay through the switching paths
Figure 15 - Constant Switch Delay: Examples of different stream rates and routing
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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 32Mb/s mode, Backplane to Local switching
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Frames N+1 and N+2
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Preliminary Information
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Frame N+4
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