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Altera_Forum's avatar
Altera_Forum
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10 years ago

DDR3 min/max/middle allowed frequencies

Hello,

As for the DDR3 clock frequency, it's currently set to 533Mhz (max allowed freq). I know that the minimal supported frequency is 300MHz.

So, can I set any frequency between 300MHz and 530Mhz?

Why does the minimum frequency requirement exist at all?

I'm working with ArriaV SX and the on-board DDR3 memory is Micron MT41K256M16HA-125IT.

Thank you!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    i believe is that that allow some margin for some clock variation due to PCB design. It is the best you configured to a frequency at the middle, as due to temperature constraint, the frequency might be vary....

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    --- Quote Start ---

    So, can I set any frequency between 300MHz and 530Mhz?

    --- Quote End ---

    Providing your chosen DDR3 memory devices supports your selection, yes.

    --- Quote Start ---

    Why does the minimum frequency requirement exist at all?

    --- Quote End ---

    The DDR3 memory's DLL will have a minimum operating frequency, below which it won't lock.

    Cheers,

    Alex