MDS105
Description
Data Sheet
The MDS105 is a fully integrated 5 port Ethernet switch designed to support the low-cost requirements of
unmanaged switch applications. The MDS105 provides features that are normally not associated with plug-and-
play technology, while not requiring an external processor to facilitate their utilization.
The MDS105 begins operating immediately at power-up, learning addresses automatically and forwarding packets
at full wire-speed to any of its four output ports or the uplink expansion port. The default configuration allows
operation without using an external EEPROM.
With an EEPROM to configure the device at power-up, however, the MDS105 provides flexible features: port
trunking, port mirroring, port-based VLANs, and Quality of Service (QoS) capabilities that are usually associated
only with managed switches.
The built-in intelligence of the MDS105 allows it to recognize and offer packet prioritization using Zarlink’s QoS
scheme. Packets are prioritized based upon their layer 2 VLAN priority tag or the layer 3 Type-Of-
Service/Differentiated Services (TOS/DS) field. This priority can be defined as transmit and/or drop priority.
The MDS105 can be used to create a 4 port unmanaged switch with one WAN router port by connecting a CPU
(ARM or MPC 850) to the additional MII port (Port 4). The only external components needed are the physical layer
transceivers and a single SBRAM, resulting in a low total system cost.
Designed to support the requirements of converging networks, the MDS105 utilizes a power conserving
architecture. To further enhance this power management, the chip automatically detects when a switch port is not
being utilized, and turns off the logic associated with that port, thereby saving power and reducing the current load
on the switch power supply.
Operating at 66 MHz internally, and with a 66 MHz interface to the external SBRAM, the MDS105 sustains full wire-
speed switching on all 5 ports.
The chip is packaged in a small 208 pin Plastic Quad Flat-Pak (PQFP) package.
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Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
