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AM69A: question for DDR layout

Daniel Cheng1
Mastermind 7255 points
Part Number: AM69A


Tool/software:

Hi Expert,

The PS11 (T-branch: 35/70) in the DDR layout guide does not match the EVM board (33/66), such as the CA signal. Which one should we refer to mainly?

Thanks

Daniel

  • 0
    TI__Guru 52955 points

    The difference between 33-ohm and 35-ohm is very small - the PCB etching tolerances will have more variance than that - so really doesn't matter.  The T-branch PS12 will likely not be achievable.  It is recommended to route them minimum trace width to get 'as close to desired' as possible.  For this reason, 33/66 is a little lower than 35/70...thus will be slightly closer to PS12 targets.  That is reason EVM went with 33/66.