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6437 interfacing DDR2

Joaquin Gonzalez
Expert 1200 points
Other Parts Discussed in Thread: TMS320DM6437

Hi to everybody,

I am going to connect a TMS320DM6437 to a DDR2 memory. I am using " Implementing DDR2 PCB Layout on the TMS320DM643x DSP (SPRAAL6A)" to design my layout. I am going to use this memory model : MT47H32M16HR -3 (DDR2 667) which is faster than the memory used in the reference design from Spectrum. I think that it is going to work without any problem since SPRAAL6A says on page 2 that the minimum JEDEC DDR2 speed grade is DDR-400 and that higher DDR2 speed grades are supported due to inherent JEDEC DDR2 backwards compatibility.

I would like to check with you guys if all that I said before is right.

Thanks in advance.

  • 0
    TI__Mastermind 41665 points

    That is right, while I have not necessarily seen the specific part number you are using used with the DM6437, as long as it is a JEDEC DDR2 compatible device at a higher speed grade than the minimum required by the DM6437 than it should work just fine. This is actually something that is quite common, as the particular speed grades used on EVM boards tend to go out of production, replaced by only faster parts which end up being used in production designs.

  • 0 in reply to Bernie Thompson TI
    Expert 1200 points

    Well what confuses me is that on the TMS320DM6437 datasheet  says:

    "Supports up to 333Mhz (data rate) BUS and interfaces with DDR-400 SDRAM"

    which to me it sounds like it is the maximum speed grade allowed.

    But in the App. note  "Implementing DDR2 PCB Layout on the TMS320DM643x DSP (SPRAAL6A)" says that the minimum JEDEC DDR2 speed grade is DDR-400 and that higher DDR2 speed grades are supported due to inherent JEDEC DDR2 backwards compatibility.

    which to me it sounds like it is the minimum speed grade allowed.

     

     

     

    Is it the minimum or the maximum then?

    Thanks a lot Bernie for your time.

     

  • 0 in reply to Joaquin Gonzalez
    TI__Mastermind 27585 points

    It is like Bernie said. All JEDEC DDR2 memories are backwards compatible, so using a higher speed grade is allowed.

    Jeff