Intel® MAX® 10 Clocking and PLL User Guide

ID 683047
Date 12/26/2023
Public
Document Table of Contents

3.1.1. Guideline: Clock Enable Signals

Intel recommends using the clkena signals when switching the clock source to the PLLs or GCLK. The recommended sequence is as follows:

  1. Disable the primary output clock by deasserting the clkena signal.
  2. Switch to the secondary clock using the dynamic select signals of the clock control block.
  3. Allow some clock cycles of the secondary clock to pass before reasserting the clkena signal. The exact number of clock cycles to wait before enabling the secondary clock depends on your design. You can build a custom logic to ensure a glitch-free transition when switching between different clock sources.