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AM1806 DDR2 interface

Charles Herder90253
Prodigy 10 points
Other Parts Discussed in Thread: AM1806

Hello,

I am using an AM1806 with DDR2 memory.

I think I remember reading in one of the design guides that it was not generally recommended to use the same 1.8V supply for DDR_DVDD and DVDD3318_A/B/C due to switching noise propagating from the IO banks to the DDR2 Signals.  Is this in fact TI's recommendation?

Also, I have seen different implementations of the DQGATE termination resistor.  For my schematic, I have 22 Ohm resistors on the D0-D15,DQS0-DQS1, and DQM0-DQM1.  I have 10 Ohms on the CLKN/P lines, and no terminators on any other pin.  In this case, should I add a terminator to the DQGATE trace?

Finally, is it OK to terminate the data pins and not the address pins for DDR2?

Thanks,

Charles

  • 0
    TI__Mastermind 27585 points

    No there is no requirement that the supplies be separate. Using a simpler PMIC than on the EVM which can only support one 1.8V output is acceptable.

    No, there is no need to have a terminator on the DQGATE line, although including a 0-ohm resistor can help if the line needs to be lengthened due to board layout error.

    Yes it is ok to terminate only the data pins, as long as all pins in the net class are terminated.

    Jeff