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ideal power track size

Discussion in 'General Electronics Chat' started by mik3ca, Jul 27, 2017.

  1. mik3ca

    mik3ca Member

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    I'm just trying to figure out what track size I should use for power. Right now, I have setup 24mil power tracks with 12mil clearance, but is that wide enough to carry 1A of current down 6 inches of track?

    Before I tried thicker tracks such as 40 mils and the eagle autorouter had a harder time routing. Now with the 24mil tracks, eagle routed the wires between 2 pads of an IC a couple of times.

    I'm afraid if I make the power track widths too small then it can't handle the current.

    Basically 90% of the board has its power fed from a 7805 voltage regulator so I have to respect its limitations.

    So is a 6 inch track with 24mil width for power with 12mil for clearance ok for 1 to 1.5A of current?
     
  2. kubeek

    kubeek Well-Known Member

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    Sugget you download Saturn PCB toolkit, it has all the calculations you need on a PCB. It says that the track will dissipate rougly 140mW and rise in temperature by 5°C. I would use a bit thicker track if you got the space, but there is not really an issue with the 24mil width.
     
  3. mik3ca

    mik3ca Member

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    Thats the thing. There's not much space between two standard pads on a DIP IC. I used the default restring values in eagle of 10mil min, 25%, and 20mil max.
     
  4. dave

    Dave New Member

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  5. mik3ca

    mik3ca Member

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    circuit.png
    This is what I'm talking about in my design. The white line is the IC outline This is a small part of how the autorouter routed my board. If I were to make the power tracks thicker then wouldn't I have to lower the clearance? and what about EMI? is this setup at least somewhat OK?

    I mean I don't want to create cross talk (signal jumping from wire to wire).

    My board has different kinds of signals and the operating speed is between 1 and 20Mhz. I decoupled each IC with 0.047uF capacitors with one capacitor pin connected no more than 2 mm away from the vcc pin of each IC.
     
  6. kubeek

    kubeek Well-Known Member

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    I would leave that meander as it is, but increase the width of the rest of the track. If you have signals at that frequency, you should better show the whole board and if possible with a schematic. I strongly suggest having a copper ground plane on the bottom layer if this is a two layer board, or in the middle if it is a four layer board, and do the layout by hand and not by autorouter, they allways leave very sketchy results on complex boards.
     
  7. mik3ca

    mik3ca Member

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    It's a single-sided board. and yes I'll have ground planes.
     

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