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iMX8M Mini EVK LPDDR4

Question asked by Tom Perman on Oct 4, 2019
Latest reply on Oct 7, 2019 by Yuri Muhin

Hi,

 

I have some questions regarding the iMX8M Mini EVK design, specifically the LPDDR4 sheet in SOM schematic "8MMINILPD4-CPU" and more general LPDDR4 questions. 


  • Why is there a 150R resistor termination on the DRAM_CK differential signals?
    • This isn't mentioned in the Hardware Design Guide, and hasn't been observed on LPDDR4 designs for other SoCs
  • What is the purpose of the DNP 10K resistors R123, R124, R121 & R122 on DRAM_CKE0/1 
  • The recommendation in the Hardware Design Guide is to use 85 Ohm differential controlled impedance for DDR DQS/CLK. However on other LPDDR4 designs these are routed at 100 Ohms. Why is this recommendation different from the standard used?

 

Thanks,

 

Tom 

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