ST AN2248 APPLICATION NOTE

AN2248

APPLICATION NOTE

Designing with the STMUX1000L Ethernet Gigabit LAN Switch

Introduction

The STMUX1000L is an 8- to 16-bit bi-directional Multiplexer/Demultiplexer. It is designed for applications that require signal routing at 10/100/1000 Megabit Ethernet speeds. The device integrates three Single Pole Dual Throw (SPDT) Channels for LED support and is available in two different packages, the TSSOP56 and QFN56.

This application note highlights various applications into which the STMUX1000L Gigabit LAN Switch can be designed, such as PC Notebooks and docking stations (see Figure 1). These are applications where several electrical characteristics impact high performance data transfer, including

■low noise between signals,

■low RON, and

■low Con and Coff capacitance.

Additionally, the superior performance of the STMUX1000L is illustrated when it is compared to a competitor’s device.

Figure 1. Typical Docking Station/Notebook Connections

Docking Station

MDI [1] +

MDI [1] –

	10/100/1000		MDI [4] +
	Base-T
			MDI [4] –
	MAC & PHY

	MDI [1] +			CAT5
	MDI [1] –
	MDI [4] +		Interface

MDI [4] –

Docking Connector

Notebook

SEL

			CAT5
STMUX1000L
		Interface
LAN Switch

AI11868

	Rev 1.0
October 2005	1/9

http:/www.st.com

				AN2248 - APPLICATION NOTE
	Contents
1	Evolution of Gigabit Ethernet Technology . .			. . . . . . . . . . . . . . . . . . . . . . . 3
	1.1	Typical Progression . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . . . . . . . . . . . . . . . . . 3
2	STMUX1000L Testing and Measurement . . . . .			. . . . . . . . . . . . . . . . . . . . . . 4
		Table 1.	Testing Equipment . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.1	–3dB Measurement . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . . . . . . . . . . . . . . . . . 5
		Figure 2.	–3dB Bandwidth Test Bench . . . . . . . . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . 5
		Figure 3.	–3dB Bandwidth Characteristics . . . . . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Cross-talk Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 4. Cross-talk Measurement Test Bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 5. Typical Cross-talk Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3	Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7
	Table 2. STMUX1000L Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7
4	Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8

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AN2248 - APPLICATION NOTE

1 Evolution of Gigabit Ethernet Technology

1 Evolution of Gigabit Ethernet Technology

Gigabit Ethernet evolved from the original 10Mbps Ethernet and 100Mbps fast Ethernet standards. At one time, many organizations believed that a 10Mbps connection would always be adequate for the average business desktop user, and that 100Mbps would be needed only in the “backbone” (the central network that links all of the Internet together).

Gigabit Ethernet technology increases the performance of the data transfer between servers and desktops, thereby reducing the traffic flow in the congested areas.

It is also a good choice because it supports a high level of Quality of Service (QoS). QoS methods are increasingly important for avoiding latency problems as voice, video, and data share the same bandwidth for Next-Generation Networking (NGN) applications.

1.1Typical Progression

Typical users of Gigabit Ethernet are the workgroups that usually need heavy bandwidth like the engineering and R&D Departments, which not only use CAD, 3D modelling and collaborative design, but also have more powerful workstations that can immediately take advantage of a high-performance connection. Other specialized business categories like medical imaging, graphic design or advertising production will also follow this new standard.

The transition to Gigabit Ethernet speeds and networks will happen in several phases which are summarized as follows:

●Phase 1

High-performance Gigabit switches are used to aggregate backbone traffic.

●Phase 2

Gigabit Ethernet is switched and routed at the network backbone with switch-to-switch connections.

●Phase 3

Greater server-to-switch bandwidth is deployed using a gigabit switch to support Gigabit Ethernet network adapter cards, boosting server connections to 1000Mbps.

●Phase 4

All servers have at least one Gigabit connection, and Gigabit becomes the standard for the highest-demand desktops and workgroups.

●Phase 5

As PCs are replaced due to normal attrition, 10/100/1000Mbps network interfaces are specified to replace 10/100Mbps connections.

●Phase 6

Servers are scaled to multi-Gigabit speeds. Older switches are replaced with Gigabit switches to take Gigabit down to the desktop. Gigabit Ethernet becomes standard for virtually all desktops.

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