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AR# 25223

Spartan-3 Generation - CCLK differences from Spartan-II/IIE


There is a difference between how the config DOUT is clocked with reference to CCLK between the Spartan-3 Generation and Spartan-II/-IIE.


The config DOUT is driven off the falling edge of CCLK for all Spartan-3 Generation devices. The Spartan-II/-IIE devices use the rising edge. When migrating a design from Spartan-II/-IIE to any Spartan-3 device, keep this difference in mind.

For more information on Spartan-3 configuration, please see the Spartan-3 Generation Configuration User Guide linked here:


AR# 25223
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article