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66AK2G02: DDR3L Routing spec'd in ps

Brian Antheunisse
Expert 5215 points
Part Number: 66AK2G02

We are wondering how to decode how you guys spec'd the DDR3L signal routing in the datasheet. The units are in picoseconds. How can we get the value in Mils(or millimeters)?

Should I use (speed of light) times (spec value in pico-second) to get the length?

Thanks,

Brian

  • 0
    TI__Guru 65405 points
    Hi Brian,

    I've forwarded this to the hardware design experts. Their feedback should be posted here.

    BR
    Tsvetolin Shulev
  • 0
    TI__Mastermind 42545 points
    Hi Brian,
    Providing the routing requirements is mils is not practical. Signals will travel at different speeds through traces with different characteristics and on different layers. You will have to compensate in the length calculation for these factors. For example, the typical propagation delay is 150 pS / in for Microstrip, or 180 pS / in for Stripline. If you have a trace running on a surface layer it will be a different length then a trace on an internal layer to match the signal delay.
    Regards,
    Bill
  • 0 in reply to Bill Taboada
    TI__Expert 5215 points
    Ok, so this answers my question on why it is spec'd that way, but it is still not entirely clear how to properly route things out.

    Are there any resources you guys know of to help understand what type of speeds to expect with certain types of routing?