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LPDDR4 memories

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joniengr081:
Hi,

I am wondering about the LPDDR4 memories that can be used with ZYNQ Ultrascale devices. I have some questions. I am referring to the memories by Micron Technology. 

1- What is the signal rank and dual rank in the memories ?
2- What is the single die package (SDP) and dual die package (DDP) ?

Daixiwen:
In a dual die package, as the name suggest you have two silicon dies in the same package. It means that your memory is divided in two and each die can be individually selected with a chip select. Your DDR memory controller will probably see this as two chips connected to the same bus.

joniengr081:
Thanks for the reply. I guess the dual memory chip will also help in routing on the custom board compared to two chips as all the data and address has to go to only one chip not two. But what is the word "rank", signal rank and dual rank are the same as single die and dual die ?

Daixiwen:
As far as I understand it, it is the same.

joniengr081:
I have checked some Xilinx documents describing memory interfaces to Ultrascale FPGA/SOC devices. One single rank configuration can be achieved with using one SDP memory which can also be called single channels single rank configuration using SDP. While two single rank can be implemented with one DDP which can also be called dual channel single rank configuration using DDP. It look like that single rank and dual rank are not the same as single die per package (SDP) and dual die per package (DDP).

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