Intel® Stratix® 10 High-Speed LVDS I/O User Guide

ID 683792
Date 7/13/2021
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

3.2.4.1. RSKM Equation

The RSKM equation expresses the relationship between RSKM, TCCS, and SW.
Figure 29. RSKM Equation


Conventions used for the equation:

  • RSKM—the timing margin between the clock input of the receiver and the data input sampling window, and the jitter induced from core noise and I/O switching noise.
  • Time unit interval (TUI)—time period of the serial data.
  • SW—the period of time that the input data must be stable to ensure that the LVDS receiver samples the data successfully. The SW is a device property and varies according to device speed grade.
  • TCCS—the timing difference between the fastest and the slowest output edges across channels driven by the same PLL. The TCCS measurement includes the tCO variation, clock, and clock skew.
Note: If there is additional board channel-to-channel skew, consider the total receiver channel-to-channel skew (RCCS) instead of TCCS. .

You must calculate the RSKM value, based on the data rate and device, to determine if the LVDS receiver can sample the data:

  • A positive RSKM value, after deducting transmitter jitter, indicates that the LVDS receiver can sample the data properly.
  • A negative RSKM value, after deducting transmitter jitter, indicates that the LVDS receiver cannot sample the data properly.
Figure 30. Differential High-Speed Timing Diagram and Timing Budget for Non-DPA Mode This figure shows the relationship between the RSKM, TCCS, and the SW of the receiver.