high frequency pcb designing

Discussion in 'General Electronics Chat' started by gehan_s, Jan 14, 2013.

  1. gehan_s

    Thread Starter Member

    Sep 17, 2012
    38
    0
    Hi all,

    I have to do routing between a pic micro controller and an ade7758 energy measuring chip. They communicate using SPI and the master clock is 1MHz. What kind of precautions do I have to take ?

    Please help me to decide max track length, width, termination (Using pull down resistors or caps) etc

    These two chips are optically isolated using a 6n137 opto isolator. Can it handle such high frequency communication ? (It says 10MBit/s but does anyone have experience with this IC?)

    Thanks in advance !!!!!!!!!!!!!!!
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,361
    1MHz is not particularly high as far as logic circuits are concerned.
    The one thing that always applies is make sure you have a 0.1μF capacitor between Vcc and GND as close to these pins as possible on every chip.

    It is also a good idea to make Vcc and GND traces wide, 50mil for example, and put a 10μF electrolytic capacitor across Vcc and GND.
     
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  3. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    The 6N137 should have no problem with the 1MHz signal. Use about a 1kΩ pull-up resistor to the V+ supply at its output.
     
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  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    PCB layout only gets odd when you get past 100Mhz to 300Mhz, depending on the number of lines that are switching at a time.

    A 1Mhz logic circuit will work on a breadboard if decoupling caps are present in quantity.
     
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  5. gehan_s

    Thread Starter Member

    Sep 17, 2012
    38
    0
    Thank you all for replying !!!!!!!!!!!!!
     
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