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AR# 43211

Spartan-6 - Simultaneous Switching Output (SSO) Calculation - What are the SSO limits when using the untuned setting?

Description

The Spartan-6 FPGA SelectIO User Guide (UG381) gives theSimultaneous Switching Output (SSO) limits for different IOSTANDARDS, however, when using the untuned settings the user guide states the following:

"Setting the OUT_TERM attribute to one of these values will override the default value of NONE, and will also override all drive-strength and slew rates that the output buffer would have been set to for the assigned I/O standard."

So, how should the SSO limits be calculated when using any of the untuned settings?

Solution

When using the untuned termination, use the PlanAhead tool to check the SSO limits. This will check all of the I/Os that are being used and indicate if the SSO limits are being exceeded.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
31905 Simultaneously Switching Noise - Where can I find documentation on SSO/SSN? N/A N/A
AR# 43211
Date Created 07/20/2011
Last Updated 12/15/2012
Status Active
Type General Article
Devices
  • Spartan-6 LX
  • Spartan-6 LXT
  • Spartan-6Q