GND & VCC Planes...

Discussion in 'General Electronics Chat' started by bob332, Jul 2, 2011.

  1. bob332

    Thread Starter Member

    Feb 14, 2011
    80
    0
    making a sensor board with 3axis acclerometer, 3axis gyro and 3axis compass. was going to do a bottom gnd plane and top 3V3 plane. incoming V is 5V so i am putting on a 3V3 LDO reg for the 3V3 plane.

    question is, will there be an issue using the 3V3 plane instead of routing the 3V3 to where it needs to go and put a gnd plane on top also w/ vias connecting the upper and lower gnd planes? i have had the the boards made but they can be thrown away if necessary as they are cheap compared to the components that will be put on them. i would rather rebuild/redesign if this manner is incorrect or would cause and issue.

    total board size is ~.75"x1.25"

    thanks in advance for your expertise,
    bob
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
  3. bob332

    Thread Starter Member

    Feb 14, 2011
    80
    0
    these 2 threads are for 2 different projects.
     
  4. bob332

    Thread Starter Member

    Feb 14, 2011
    80
    0
    any suggestions in regards to this?
     
  5. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    I can't imagine what kind of problem you might have. 3.3 volts just isn't all that mysterious. Do you have a problem with the board operating correctly? Are high frequencies involved?
     
  6. bob332

    Thread Starter Member

    Feb 14, 2011
    80
    0
    the board i have finished just has a gyro on it and it works very well. i have not finished the one w/ the gyro and accel or the one w/ the gyro, accel and compans as i just wanted to do it right and if that meant a new design i was ok w/ that, so i have not ordered the solder stencils for the 6dom and 9dom ones yet. my reason for concern is that i see other board designs with similar components and they have the 2 gnd planes. i noticed this after the fact.

    i would say the i2c communication is the highest frequency @ 400KHz on the board.

    here is the schematic and here is the board

    if anybody would mind giving me some pointers/suggestion/criticism i would be very thankful.

    thanks in advance for your time,
    bob
     
  7. #12

    Expert

    Nov 30, 2010
    16,330
    6,818
    Looks pretty good to me. The basic principle you are working with is that ground planes stop high frequency problems. The 3v3 copper is as good as a ground plane if it is AC grounded. For that, I suggest paralleling the 1uf and higher filter caps with .01uf ceramics because they have better high frequency characteristics. Or was that .001 ceramics?

    That's as good as I go.
     
    bob332 likes this.
  8. bob332

    Thread Starter Member

    Feb 14, 2011
    80
    0
    thanks for taking a look. appreciate the info :)
     
Loading...