Flexible & Versatile PCI Express

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Features

PEX 8508 General Features

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8-lane PCI Express switch

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Integrated SerDes

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Up to five configurable ports

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19mm x 19mm, 296-ball PBGA

package

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Typical Power: 1.6 Watts

PEX 8508 Key Features

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Standards Compliant

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PCI Express Base Specification, r1.1

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Standard SHPC Specification, r1.1

(hot-plug)

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High Performance

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Non-blocking internal architecture

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Full line rate on all ports

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Cut-Thru latency: 150ns

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Non-Transparent Bridging

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Configurable Non-Transparent port

for Multi-Host or Intelligent I/O

Support

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Flexible Configuration

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Five highly flexible & configurable

ports (x1, x2, or x4)

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Configurable with strapping pins,

EEPROM, I

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Lane and polarity reversal

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PCI Express Power Management

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Link power management states: L0,

L0s, L1, L2/L3 Ready, L2 and L3

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Device states: D0 and D3hot

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Vaux, WAKE#, Beacon support

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Spread Spectrum Clock

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Dual clock domain

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Quality of Service (QoS)

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Two Virtual Channels per port

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Eight Traffic Classes per port

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Fixed and Round-Robin Virtual

Channel Port Arbitration

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Reliability, Availability, Serviceability

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5 Standard Hot-Plug Controllers

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Upstream port as hot-plug client

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Transaction Layer end-to-end CRC

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Poison bit

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Advanced Error Reporting

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Lane Status bits and GPO available

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Per port error diagnostics

• Bad DLLPs

• Bad TLPs

• CRC errors

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JTAG boundary scan

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Fatal Error out-of-band signal option

Multi-purpose and Feature Rich PCI Express Switch Family

The ExpressLane™ PEX 8508 device offers PCI Express switching capability

enabling users to add scalable high bandwidth, non-blocking interconnection to a

wide variety of applications including intelligent network interface cards, office

automation products, mezzanine cards, servers, storage systems,

communications platforms, laptop docking stations, and embedded-control

products. The PEX 8508 switch can be used as a fan-out or aggregation type

switch, and is equally well-suited to peer-to-peer switching applications.

Highly Flexible Port Configurations

The PEX 8508 offers highly configurable ports. There are a maximum of five ports

and eight lanes that can be configured to any legal width from x1 to x4, in any

combination to support your specific bandwidth needs. The ports can be symmetric

(each port having the same lane width) or asymmetric (ports having different lane

widths). If you can think of a port/lane combination, you can configure it! Any of

the ports can be designated as the upstream port, and you can even dynamically

change the upstream port.

End-to-end Packet Integrity

The PEX 8508 provides end-to-end CRC protection (ECRC) and Poison bit support

to enable designs that require guaranteed error-free packets. These features are

optional in the PCI Express specification, but PLX provides them across its entire

ExpressLane switch product line.

Non-Transparent “Bridging” in a PCI Express Switch

The PEX 8508 supports full non-transparent bridging (NTB) functionality to allow

implementation of multi-host systems and intelligent I/O modules in applications

such as intelligent adapter cards, processor isolation, and office automation. To

ensure quick product migration, the non-transparency features are implemented in

the same fashion as in standard PCI applications.

Non-transparent bridges allow systems to isolate memory domains by presenting the

processor subsystem as an endpoint, rather than another memory system. Base

address registers are used to translate addresses; doorbell registers are used to send

interrupts between the address domains; and scratchpad registers are accessible from

both address domains to allow inter-processor communication.

Two Virtual Channels

The PEX 8508 switch supports two full-featured Virtual Channels (VCs) and eight

Traffic Classes (TCs). The mapping of Traffic Classes to port-specific Virtual

Channels allows for different mappings for different ports. In addition, the devices

offer user-selectable Virtual Channel arbitration algorithms to enable users to fine

tune the Quality of Service (QoS) required for a specific application.

Low Power with Granular SerDes Control

The PEX 8508 provides low power capability that is compliant with the PCI Express

power management specification. The SerDes physical links can be turned off when

unused for even lower power. Support for Vaux, Wake#, and Beacon allows D3cold

operation and is crucial in such applications as docking stations.

PEX 8508

Version 1.7 2007