SNLA435A September   2023  – January 2024 DS320PR1601 , DS320PR410 , DS320PR810

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Device Overview
  6. 3Intention of Eye Scan
    1. 3.1 An Introduction to Lane Margining
    2. 3.2 How Does Eye Scan Work?
    3. 3.3 Programming Steps for Manual Eye Scan Capture
    4. 3.4 Eye Scan Capture Registers
    5. 3.5 CTLE Sweep Result
    6. 3.6 Eye Scan DAC Range
  7. 4Eye Scan Applications
    1. 4.1 Eye Scan Application: PCIe Compliance
    2. 4.2 Eye Scan Application: System
  8. 5Eye Scan in SigCon Architect GUI
  9. 6Summary
  10. 7References
  11. 8Revision History

1 Introduction

PCI-Express (PCIe) is a high-speed serial computer expansion bus standard common to desktop and server motherboards as an interface to graphics cards, network interface cards, hard disk drives, solid state drives, and various other hardware connections. When designing a motherboard or riser card for PCIe where the PCB’s high-speed traces or connecting cable’s insertion loss exceeds the maximum PCIe insertion loss requirement (36dB at PCIe Gen5.0, 32GT/s), a linear redriver can be used to compensate for added inter-symbol interference (ISI) induced by added insertion loss on these interconnect mediums. Texas Instruments PCIe Gen5.0 linear redrivers deploy continuous time linear equalizers (CTLE) on their receivers to provide a programmable high-frequency boost. This is followed by a linear output driver, creating a linear data path to preserve transmit preset signal characteristics while staying transparent to PCIe link training.

This application note describes the Texas Instruments PCIe Gen5.0 redrivers Eye Scan feature, which provides additional insight into vertical eye quality at the redriver’s transmitter output pins. This document includes details on the Eye Scan feature capabilities and real-world examples of Eye Scan results.