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SZack's avatar
SZack
Icon for Occasional Contributor rankOccasional Contributor
4 years ago

Cyclone V internal oscillator specification

What is the frequency specification for the internal oscillator? In the handbook and Quartus itself it says you can choose a 12.5, 25, 50 or 100 MHz internal oscillator but in the datasheet it only shows a 12.5 MHz setting. Is the datasheet wrong?

This is what the datasheet says:

In the Cyclone V Handbook on page 7-18 it says:

If you use the internal oscillator, you can choose a 12.5, 25, 50, or 100 MHz clock under the Device and Pin Options dialog box, in the Configuration page of the Intel Quartus Prime software.

And in Quartus (I looked in 18.1) it gives the same four options described in the Handbook.

Steve

3 Replies

  • Ash_R_Intel's avatar
    Ash_R_Intel
    Icon for Regular Contributor rankRegular Contributor
    4 years ago

    Hi,

    There is no specification mentioning the internal oscillator frequency. However, based on internal team discussions, I came to know that this oscillator is meant for configuration and initialization only. It is not recommended for user design.


    Regards.


    • SZack's avatar
      SZack
      Icon for Occasional Contributor rankOccasional Contributor
      4 years ago

      Hi Ash_R,

      Actually I specifically mention where in the documentation it specifies the different frequencies that are allowed. I'm not asking for how accurate the clock is or how much jitter it has. And I realize it is only meant for configuration only. What I was pointing out was that the datasheet only mentions a 12.5 MHz option whereas the Handbook and Quartus provide four different frequency options.