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AR# 29790

Spartan-3E/-3A - Can the Digital Clock Managers (DCMs) handle Spread Spectrum clock inputs?


Are any of the Spartan-3 Generation DCMs able to handle spread spectrum clock inputs?


The Spartan-3E, Spartan-3A, Spartan-3AN, and Spartan-3A DSP FPGA DCMs accept typical spread spectrum clocks. The DLL part of the DCM tracks the frequency changes created by the typical spread spectrum clock to drive the global clocks to the FPGA fabric. The spread spectrum clock must meet the DLL input requirements as specified in the device data sheets. See the Input Clock Jitter Tolerance and Delay Path Variation specifications in the Recommended Operating Conditions for the DLL, CLKIN_CYC_JITT_DLL and CLKIN_PER_JITT_DLL.

The DFS can track a typical spread spectrum input as long as it meets the input clock specifications.
AR# 29790
Date 12/15/2012
Status Active
Type General Article
  • Spartan-3A
  • Spartan-3AN
  • Spartan-3E
  • Spartan-3A DSP
  • Digital Clock Manager (DCM) Module