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Explorer
Explorer
658 Views
Registered: ‎04-21-2017

Zynq DDR2 and tFAW-parameter for ISSI device

Dear Forum,

 

Having only worked with Xilinx Zynq dev-kits to date, I am now having to setup a custom DDR2 interface for the PS in a Zynq 7030 device. In the ISSI datasheet I have managed to find all but one of the parameters that are required to fill in the Zynq-PS DDR-configuration wizard. 

 

Can anyone tell me where I will find or how I should calculate tFAW(ns). The ISSI chip in question is an IS43DR16160B-37CBL.

 

TTFN.

 

DJE666

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Xilinx Employee
Xilinx Employee
634 Views
Registered: ‎07-30-2007

Re: Zynq DDR2 and tFAW-parameter for ISSI device

I'd suggest first checking with ISSI. Otherwise, perhaps check the JEDEC standard. And finally, check other vendor datasheets.
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Voyager
Voyager
620 Views
Registered: ‎10-01-2007

Re: Zynq DDR2 and tFAW-parameter for ISSI device

tFAW is only relevant when a device has >4 banks. The ISSI device referenced only has 4 banks. A good explanation of tFAW is in the Tech Note below.

https://www.micron.com/~/media/documents/products/technical-note/dram/tn4716.pdf

 

Since it is irrelevant, I would guess that you could put anything you want in there. However, if you want to be safe, you could put 4 * tRRD = 40 ns. Maybe someone at Xilinx could confirm that.

 

Bryan