RTD Embedded Technologies, Inc.
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14
LAN17255HRHR User’s Manual
4
Functional Description
Block Diagram
4.1
The Figure below shows the functional block diagram of the LAN17255HR. The various parts of the block diagram are discussed in the
following sections.
Figure 5: LAN17255HR Block Diagram
BroadCom Gig-Ethernet Switch
4.2
The main component of the LAN17255HR is the BroadCom BCM53115 Gigabit Ethernet switch. This is an industrial temperature rated, 5 port
Gigabit Ethernet switch. This switch contains 5 full-duplex 10/100/1000 BASE-TX Ethernet transceivers for network interfacing. All 5 ports are
brought to RJ-45 connectors on the board. This allows the LAN17255HR to work as a switch in a stacked system. In a stand-alone system the
BroadCom switch acts as a basic Ethernet switch. Any port can be used as an upstream port to supply a connection to the 4 other ports.
Onboard LEDs and External LED Connectors
4.3
The LAN17255HR has onboard LEDs for each of the five Ethernet ports on the board. The setting for the onboard LEDs is to show link activity,
link status and speed at 10/100/1000M. To bring the LEDs out of an enclosed system, there are 4-pin 0.1 inch DIL connectors for each port
that can be wired to external LED circuitry. These signals can source or sink 24 mA and the board has a jumper option for 3.3 volt or ground to
facilitate external LED configuration.
