PM3351-SW datasheet(39/268 Pages) PMC

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PM3351 ELAN 1X100

DATA SHEET

PMC-970113

ISSUE 3

SINGLE PORT FAST ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

FUNCTIONAL DESCRIPTION

Overview

This section will provide an overview of the PM3351 ELAN 1x100 components, the

device initialization and configuration process, the structures built and used by the

device to perform its functions, and a brief description of how packets are switched by

the device.

System Components

In order to describe the functions and operation of the ELAN 1x100 device, it is first

necessary to discuss the operating environment that is intended to be built around it. A

typical simple switching subsystem utilizing the ELAN 1x100 device consists of:

The ELAN 1x100 device itself. (Clearly, a complete system will include more

than a single ELAN 1x100 device, but this is not shown in the diagram below.)

A set of SRAM devices that provide the operating memory for the ELAN 1x100.

This memory should be mapped to the lowest bank of the ELAN 1x100 address

space (i.e., addresses starting at 0x000000 hex). The amount of SRAM

provided is a system-dependent parameter; a minimum system with about 150

kB of buffer space and around 1200 MAC addresses in the address table

requires 512kB of SRAM. SRAM requirements for this and other system

configurations may be computed using parameters supplied later in this

document.

An EPROM containing the bootstrap image for the ELAN 1x100 (i.e., the

operating firmware, operating parameters, and system initialization code) if this

ELAN device is designated as the system master. This EPROM is mapped to

the second lowest bank of the ELAN 1x100 memory address space (the 4 MB

address range starting at address 0x400000 hex.) The size of the EPROM is

highly dependent on the operating configuration of the ELAN 1x100, with the

minimum requirement being 32 kB.

External transceiver devices that implement the PHY layer functions required for

100BaseT Ethernet.

An LED register, connected to a bank of eight LEDs, that may be used to report

status information for diagnostic purposes if required. The LED register is

mapped into the third bank of ELAN 1x100 memory address space, starting at

0x800000 hex.

A system voltage monitor or other means of asserting a system reset for a

specified time after the power supply voltage has stabilized, plus, if desired, a

pushbutton switch for forcing a system reset after power-up.

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