MT90871 Zarlink Semiconductor, MT90871 Datasheet - Page 25

• Manufacturer Part Number: MT90871
• Description: Flexible 8K Digital Switch (F8KDX)
• Manufacturer: Zarlink Semiconductor

Data Sheet
6.0
The MT90871 incorporates two connection memories, Local Connection Memory and Backplane Connection
Memory.
6.1
The Local Connection Memory (LCM) is 16-bit wide with 4,096 memory locations to support the Local output
port. The most significant bit of each word, bit [15], selects the source stream from either the Backplane or the
Local port and determines the Backplane-to-Local or Local-to-Local data routing. Bits [14:13] select the control
modes of the Local output streams, namely the per-channel message and the per-channel high impedance
output control modes. In Connection Mode (Bit14 = LOW), Bits [12:0] select the source stream and channel
number as detailed in Table 4. In Message Mode (Bit14 = HIGH), Bits [12:8] are unused and Bits [7:0] contain
the message byte to be transmitted.
(16Mb/s)
(16Mb/s)
(8Mb/s)
(8Mb/s)
(8Mb/s)
(2Mb/s)
(8Mb/s)
(4Mb/s)
BSTo1
BSTo1
LSTo1
LSTo1
BSTi0
BSTi0
LSTi0
LSTi0
FP8o
Figure 15 - Constant Switch Delay: Examples of different stream rates and routing
Connection Memory Description
Local Connection Memory
254
254
CH
CH
127
127
CH
CH
127
127
CH
CH
CH
CH
63
31
255
255
CH
CH
CH
CH
Frame N
0
0
CH
CH
CH
CH
CH
CH
0
0
0
0
0
0
CH
CH
1
1
Example showing Backplane to Backplane switching
Example showing Backplane to Local switching
Example showing Local to Backplane switching
Example showing Local to Local switching
254
254
CH
CH
127
127
CH
CH
127
127
CH
CH
CH
CH
63
31
255
255
CH
CH
Zarlink Semiconductor Inc.
Frames N+1 and N+2
Frame N+3
CH
CH
0
0
CH
CH
CH
CH
CH
CH
0
0
0
0
0
0
CH
CH
1
1
254
254
CH
CH
127
127
127
127
CH
CH
CH
CH
CH
CH
63
31
255
255
CH
CH
CH
CH
Frame N+4
0
0
CH
CH
CH
CH
CH
CH
0
0
0
0
0
0
CH
CH
1
1
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