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Is it possible to use four 16b DDR2 devices on the C6455 DDR2 bus?

Smokensparks
Intellectual 440 points
Other Parts Discussed in Thread: TMS320C6455

Hi,

My customer has the following questions:

For the TMS320C6455, is it possible to use four 16-bit DDR2 devices on the DDR2 bus?

We want to use a 32-bit bus and have the option of either using two 2Gb DDR2 devices, or four 1Gb devices to get 512 MByte of DDR2 SDRAM.

There is only one chip select, but with appropriate logic, can we decode the bank select signals and the chip select to access multiple devices for a given data bus?

Thanks,

Rick

  • 0
    TI__Mastermind 41665 points

    Smokensparks said:
    For the TMS320C6455, is it possible to use four 16-bit DDR2 devices on the DDR2 bus?

    In general this would not be recommended, only up to two 16 bit devices in a 32 bit wide bus configuration are supported. The DDR2 interface was designed to have only a single DDR2 device on any given data bus pin, having multiple devices connected to the same physical DDR2 data pins can lead to loading issues, and with the tight requirements of the DDR2 interface this can lead to instability and failure. In general TI can only guarantee successful operation of the DDR2 interface if the layout guide lines in the DDR2 layout application note for C6455 are followed, which preclude using 4 DDR2 devices.