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
MDI [1] + MDI [1] MDI [4] +
CAT5 Interface
Docking Station
MDI [4]
Docking Connector
SEL MDI [1] + MDI [1]
Notebook CAT5 Interface
10/100/1000 Base-T MAC & PHY
MDI [4] + MDI [4]
STMUX1000L LAN Switch
AI11868
October 2005
Rev 1.0 1/9
http:/ww w.st .com
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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 3dB Bandwidth Test Bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3dB Bandwidth Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Cross-talk Measurement Test Bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Typical Cross-talk Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 .1
3dB Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. Figure 3.
2 .2
Cross-talk Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4. Figure 5.
3
Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 2. STMUX1000L Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
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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.
1.1
Typical 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:
P has e 1 High-perfor mance Gigabit switches are used to aggregate backbone traffic. P has e 2 Gigabit Ethernet is switched and routed at the network backbone with switch-to-switch connections.
P has e 3 Greater server-to-switch bandwidth is deployed using a gigabit switch to support Gigabit Ethernet network adapter cards, boosting server connections to 1000Mbps.
P has e 4 All servers have at least one Gigabit connection, and Gigabit becomes the standard for the highest-demand desktops and workgroups.
P has e 5 As PCs are replaced due to normal attrition, 10/100/1000Mbps network interfaces are specified to replace 10/100Mbps connections.
P has e 6 Ser vers 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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2 STMUX1000L Testing and Measurement
AN2248 - APPLICATION NOTE
2
STMUX1000L Testing and Measurement
Basic testing instruments (see Table 1) and benches (see Figure 2 on page 5 and Figure 4 on page 6) were used to perform the 3dB bandwidth and Cross-talk measurements.
Figure 3. and Figure 5. illustrate the importance of a very high bandwidth and low noise device between the channels to enable a correct data transfer when the laptop is connected to the docking station.
Table 1. Testing Equipment
Brand Tektronics Dual Programmable Power Supply Generator Agilent Technologies Network Analyzer 300KHz to 3GHz Mo d e l PS2521G E5070B
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2 STMUX1000L Testing and Measurement
2.1
3dB Measurement
The STMUX1000L 3dB bandwidth measurement is conducted as follows: 1. 2. 3. The STMUX1000L switch is connected to the testing circuit and turned ON. A 10dBm sine signal is forced across the switch with a frequency sweep of 300KHz to 1GHz. The output frequency values are checked to make sure they remain the same, while the signal is reduced by 3dB (in the case of Figure 3, signal reduction starts at 506.668MHz). 3dB Bandwidth Test Bench
Testing Circuit Network Analyzer Source 50 Input 50
Figure 2.
VIN
50 50 A B 50 50 C D SEL
A0 B0 A1 B1 C0 D0 C1 D1
50 50 50 50 50 50 50 50
VOUT
AI11869
Figure 3.
3dB Bandwidth Characteristics
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2 STMUX1000L Testing and Measurement
AN2248 - APPLICATION NOTE
2.2
Cross-talk Measurement
The STMUX1000L cross-talk measurement is conducted as follows: 1. 2. 3. The STMUX1000L switch is connected to the testing circuit and turned ON. A 10dBm sine signal is forced across the switch with a frequency sweep of 300KHz to 1GHz. The switch is turned OFF and the residual signal level (attributed to the cross-talk phenomenon) is measured (in the case of Figure 5, the residual signal level is 47.148dB). Cross-talk Measurement Test Bench
Network Analyzer Source 50 Input 50
Figure 4.
VIN
50 50 A B 50 50 C D SE
A0 B0 A1 B1 C0 D0 C1 D1
50 50 50 50 50 50 50 50
VOUT
AI11870
Figure 5.
Typical Cross-talk Results
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3 Features and Benefits
3
Features and Benefits
Table 2 shows the main STMUX1000L features and their corresponding benefits or applications.
For example, the lower quiescent current (IQ) feature reduces battery consumption, making the STMUX1000L an excellent choice for portable applications. Table 2. STMUX1000L Features and Benefits
Features Low R DS (ON) = 5 (typ) Bandwidth = 350MHz 3dB (typ) Low Channel C on = 6pF (typ) Low ICC Consumption Three spare SPDT switches Available in QFN56 package
1. Measur ement valid for V CC = 3.3V.
Benefits or Applications Low Return Loss Can be used for Ethernet standards (e.g., 10/100/1000 Base-T) Consistently high bandwidth performance Por table applications LED support Space saving on the PCB
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4 Revision History
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4
Revision History
Date 06-October-2005 Revision 1. 0 First edition Changes
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4 Revision History
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners 2005 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com
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