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82551QM/82540EM Interchangeable LOM Design Guide Application Note (AP-432)

Intel® 82551QM/82540EM Interchangeable LOM (AP-432)


The Intel® 82540EM Gigabit Ethernet Controller and the Intel® 82551QM Fast Ethernet Controller are both manufactured in a footprint compatible 15 mm x 15 mm, 196-Ball Grid Array (BGA) package. Many of the critical signal pin locations on the 82540EM are identical to signals on the 82551QM, allowing designers to create a single design that accommodates both parts. However, the usage of some signals and pins differ between the two devices. Thus, they are not referred to as pin compatible. They are footprint compatible, which means that they share the same package size and the same number and pattern of pins, allowing the signal layout to be flexible and cost effective and to be used as a multipurpose design. This enables a single board design for either device maximizing its value and matching performance needs.

This design is also backwards compatible with the 82559 and 82550 controllers. Engineers with experience implementing these previous generations of Intel Fast Ethernet controllers can easily and confidently update older designs or modify those designs enabling upgrades for the 82540EM Gigabit Ethernet Controller to meet customer requirements while minimizing design variables.

The 82559 and 82550 designs are not forward compatible to this design. Support for features such as IP Security, Alert Standard Format, and Alert on Lan*, is dependant on the feature set of the controller, which is detailed in the device product brief or datasheet. These documents should be referenced to better understand the capabilities of the device selected for a design.

Document Scope
This application note identifies the design differences between the 82540EM and the 82551QM.

Section 2.0, “Pin Number to Signal Mapping,” contains a table summarizing the population options for both devices, and a reference schematic is contained in Section 4.0, “Reference Schematic.”

Read the full Intel® 82551QM/82540EM Interchangeable LOM application note.

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