
MT90870
Data Sheet
20
Zarlink Semiconductor Inc.
2.048 Mb/s are included, there will be a corresponding reduction in switch capacity although conversion between
differing rates will be maintained.
2.1.1 Backplane-to-Local Path
The device can provide data switching between the Backplane input port (8192 channels) and the Local output port
(4096 channels). The Local Connection Memory determines the switching configurations.
2.1.2 Local-to-Backplane Path
The device can provide data switching between the Local input port (4096 channels) and the Backplane output port
(8192 channels). The Backplane Connection Memory determines the switching configurations.
2.1.3 Backplane-to-Backplane Path
The device can provide data switching between the Backplane input (8192 channels) and output (8192 channels)
ports. The Backplane Connection Memory determines the switching configurations.
2.1.4 Local-to-Local Path
The device can provide data switching between the Local input (4096 channels) and output (4096 channels) ports.
The Local Connection Memory determines the switching configurations.
2.1.5 Uni-directional Switch
The device may be optionally configured to provide a 12,288 x 12,288 uni-directional switch by grouping together
Backplane and Local input and output streams.
2.2 Port Data Rate Modes and Selection
The selection of individual stream data-rates is summarized in Table 1.
2.2.1 Local Port Rate Selection
The Local port has 16 input (LSTi0-15) and 16 output (LSTo0-15) data streams. All input and output streams may
be individually selected for operation at a data rate of either 2.048 Mb/s, 4.096 Mb/s, 8.192 Mb/s or 16.384 Mb/s.
The timing of the input and output clocks and frame pulses are shown in Figure 6, Local Port Timing Diagram for
2,4,8 and 16 Mb/s stream rates.
2.2.1.1 Local Input Port
The bit rate for each input stream is selected by writing to a dedicated Local Input Bit Rate Register (LIBRR0-15).
Refer to Table 41, Local Input Bit Rate Register (LIBRRn) Bits.
Stream Number
Rate Selection Capability
(for each individual stream)
Input stream - Backplane 0-15 (BSTi0-15)
2.048, 4.096, 8.192 or 16.384 Mb/s - Non-32 Mb/s Mode
32.768 Mb/s - 32 Mb/s Mode
Input stream - Backplane 16-31 (BSTi16-31)
2.048, 4.096, 8.192 or 16.384 Mb/s - Non-32 Mb/s Mode
Unused - 32 Mb/s Mode
Output stream - Backplane 0-15 (BSTo0-15)
2.048, 4.096, 8.192 or 16.384 Mb/s - Non-32 Mb/s Mode
32.768 Mb/s - 32 Mb/s Mode