Functional Description
The MT90840 Distributed Hyperchannel Switch is a large switching, multiplexing, and rate-adapting device. The MT90840 bridges serial-bus telecom components, using the Zarlink ST-BUS or other industry-standard serial buses, onto a higher speed “backbone”. Mixed data, voice and video signals can be time-interchanged or multiplexed from serial Time Division Multiplexed (TDM) streams onto a high speed parallel bus. The parallel bus can be used for interconnect, or an external framer can be connected to the parallel bus to access serial isochronous backbones operating at up to 155 Mbps SONET rates (STS-3).

FEATUREs
• Time slot interchange function between eight pairs of ST-BUS/GCI/MVIPä streams (512 channels) and parallel data port
• Programmable data rates on the parallel port (19.44, 16.384, or 6.480 Mbyte/s)
• Programmable data rates on the serial port (2.048 Mbps, 4.096 Mbps or 8.192 Mbps)
• Supports star and point-to-point connections, and unidirectional or bidirectional ring topologies for distributed systems
• Input-to-output bypass function on the parallel data port for use in add/drop applications
• Provides elastic buffer at parallel input port in the receive direction
• Provides byte switching for up to 2430 channels
• Per-channel direction control on the serial port side
• Per-channel message mode and high-impedance control on both parallel and serial port sides
• 8-bit multiplexed microprocessor port compatible with Intel and Motorola microcontrollers
• Guarantees frame integrity when switching nX64 wideband channels such as ISDN H0 channel
• Provides external control lines allowing fast parallel interface to be shared with other devices
• Diagnostic alarm functions and clock phase-status word for clock monitoring
• IEEE 1149 (JTAG) boundary scan port

APPLICATIONs
• Bridging ST-BUS/MVIP buses to high speed Time Division Multiplexed backplanes at SONET rates (STS-1, STS-3)
• High speed isochronous backbones for distributed PBX and LAN systems
• Switch platforms of up to 2430 channels with guaranteed frame integrity for wideband channels
• Serial bus control and monitoring
• Data multiplexing
• High speed communications interface