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AR# 43428

Spartan-6 - Can I use Sub-LVDS as input to a Spartan-6 FPGA I/O?

Description

Is it possible to drive a Spartan-6 FPGA I/O with a Sub-LVDS input?

Solution

It is possible, however, the electrical characteristics of the Sub-LVDS input need to be checked to ensure that it meets the Spartan-6 FPGAinput requirements.

Take the following Sub-LVDS specifications:

Parameter Min Typical Max Unit
Fixed common mode voltage VCMF 0.8 0.9 1.0 V
Differential voltage swing VOD 100 150 200 mV
Drive current range 0.833 1.5 2 mA

In the case above the Standard LVDS input buffer can be used:

For the input swing VID Min/ Max 100mV / 600mV the Sub-LVDS is 100 / 200mV; so, this is within spec.

The LVDS common mode it is 0.3mV -> 2.35V and the Sub-LVDS is 0.8mV -> 1V; which is also within spec.

The normal LVDS termination can be used. However, an IBIS simulation should be done in all cases to ensure the signal integrity is correct.

AR# 43428
Date Created 08/11/2011
Last Updated 02/18/2013
Status Active
Type General Article
Devices
  • Spartan-6 LX
  • Spartan-6 LXT
  • Spartan-6Q