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Layout considration for SDRAM which speed is 100MHz

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  • Layout considration for SDRAM which speed is 100MHz

    Dear Robert

    I have a LPC4357 with IS42S32800 in my PCB. The Maximum speed is 100MHz. I want to match the length of addresses and data buses. I put all of them into the individual groups and I know how to match the signals into the altium according to your shematic and pcb design course. But which length should be our reference to match all the signal groups? Is it ok to only match the address and data buses of this memory?
    I couldn't find any design guide for this type of SDRAM!

    Thanks in advance.

  • #2
    I mean how we can know, the tefrence length to match all of them based on it? Which singnals, data, address, clocks.. have to be in the same length?

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    • #3
      Have a look at recommendations of standard interfaces like IDE / PCI / ISA. These are slower, but you will get an idea of what is important. Normally, you may want to make data signals similar length, and to make the strobe signals (e.g. Read / Write ) a little bit longer. Clock is usually the longest one.

      Try google for "COM Express Design Guide" e.g. https://www.picmg.org/wp-content/upl...2013-12-06.pdf

      Find section about Routing Rules for Single Ended Interfaces and have a look at the tables. I hope this helps Here is an example of IDE rules:


      Click image for larger version

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