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Reference clock of DLL (Delay Line) in Read Path in DDR mode.

Question asked by Takayuki Ishii on Jun 21, 2018
Latest reply on Jun 22, 2018 by Takayuki Ishii

Hello community,


I have one question about reference clock(ipp_card_clk_in) frequency of DLL (Delay Line)

if uSDHC is in DDR(dual data rate) mode.

I think that

   * 50MHz in SD3.0 DDR mode

   * 52MHz in EMMC4.4 DDR mode


So reference clock period of ipp_card_clk_in are 

   * 20ns = 1/50MHz in SD3.0 DDR mode

   * 19.2ns = 1/52MHz in EMMC4.4 DDR mode.


It is not 100 or 104MHz(10 or 9.62nsec) in each DDR mode.

Is it correct?


Best regards,