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Original question:

DDR3 selection

AM4376: DDR3L Speed question and board.c configuration using EMIF configuration tool

Kamil Muza1
Prodigy 220 points
Part Number: AM4376

Hello all,

On our custom design based on the AM437X_EVM_SK, we are using the following 2x RAM chips NDL16PFJ-8KIT, which are 800 Mhz, 1Gb x 16 DDR3L. 

I'm working on the u-boot port and I'm up to the point I have to modify board.c file to specify the DDR timing configuration.
Because the AM437X requires 400 Mhz and these are almost impossible to find, how can I go by configuring an 800 Mhz RAM with all the timing configurations if the EMIF configuration tool www.ti.com/.../sprac70 caps at 400 Mhz? Should I use a config tool for a more recent platform that allows higher speeds? Not sure how to proceed from here..

Thank you very much!

  • 0
    TI__Guru*** 125430 points

    Kamil,

    There is no requirement or expectation that you match the DDR3 speed bin to the speed of the DDR3 bus.  It is normal to be purchasing a DDR3-1600 device (or even faster) to use with the AM437x.

    When you are entering timing parameters into the spreadsheet, you should be sure to use the speed bin that corresponds to the device you are buying.  In other words you should not take your timing numbers from the DDR3-800 column of the data sheet because that's not what you're buying.  Use the timing numbers from the DDR3-1600 column (or whatever you're buying).

    There is generally a section called "speed bin tables" or something along those lines for being able to determine the proper CAS latency and CWL when running at a reduced frequency.  In Step 1B the CAS latency entered there should be the FULL SPEED CAS Latency.  We have tried to make that clear in the spread sheet. For Step 3 of the spreadsheet, CL and CWL will come from the speed bins table and should reflect the speed at which you'll actually be operating, i.e. 400 MHz / 2.5 ns.

    I hope this helps clarify a bit.

    Best regards,
    Brad