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AR# 64247

UltraScale - Bidirectional LVDS termination schemes

Description

Is bidirectional LVDS supported on UltraScale?

What is the required termination scheme?

How does DIFF_TERM behave?

Solution

The SelectIO User Guide (UG571) states that bidirectional buffers are supported for LVDS and LVDS_25 and notes the following:

"The bidirectional configuration on these I/O standards is a fixed impedance structure optimized to 100 differential.
They are intended to only be used in point-to-point transmissions that do not have turn around timing requirements.
Use BLVDS_25 for bus structures."

Primitive Driving 3-Stated/Receiving Bank Type
OBUFDS Termination On NA Both HR and HP
OBUFTDS Termination On Termination On Both HR and HP
IBUFDS NA
DIFF_TERM = TRUE Termination On
DIFF_TERM = FALSE Termination Off
Both HR and HP
IOBUFDS Termination On
TERM ON (irrespective of DIFF_TERM)
DIFF_TERM = TRUE Termination ON
DIFF_TERM = FALSE Termination ON
Both HR and HP
 
AR# 64247
Date Created 04/14/2015
Last Updated 04/15/2015
Status Active
Type General Article
Devices
  • Kintex UltraScale
  • Virtex UltraScale