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AM3874: AM3874, custom board and DDR3 faster than 531MHz

Jacek Kryszyn
Prodigy 200 points
Part Number: AM3874

Hello,

I am developing a device containing AM3874. The board is custom. The prototype was fitted with DDR3 400 MHz which works ok, but I would like to use faster RAM (at least 675 MHz). Theoretically the processor can work with up to DDR3-1066 but I found that there is no such option in u-boot configuration, only 400 and 533 MHz options available (I've checked arch/arm/include/asm/arch-ti814x/ddr_defs.h). What has to be done in order to work with DDR3 675 MHz or even 796 MHz? Is it possible?

  • 0
    TI__Guru**** 170625 points

    Hi Jacek,

    The 533MHz DDR3 max frequency in u-boot is NOT only u-boot SW limitation, this is AM387x device limitation. Which means that you can not use AM387x DDR3 with more than 533MHz, this is NOT possible at all.

    DDR3-1066 correspond to 533MHz, not to 1066MHz. 1066 is data transfer rate [MT/s], not clock frequency [MHz]. The data rate (in MT/s) is twice the I/O bus clock (in MHz) due to the double data rate of DDR memory.

    Refer to AM387x datasheet, sections:

    9.13.4 DDR2/DDR3 Memory Controller Electrical Data/Timing
    9.13.4.2.4.1 Compatible JEDEC DDR3 Devices

    Regards,
    Pavel