Page 216 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards
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FIGURE 9-4 Initial component placement.
In considering the board design, there are two areas where it is worth some manual layout before
we unleash the autorouter. These are
• The critical layout considerations for the power-supply chip IC2 and its associated
components
• The power supply and outputs of the motor controller chip IC3
Laying Out the Power Supply
As you can see, the power-supply components take almost a third of the right-hand side of the board.
The switched-mode power supply is based around the LM2596S chip. The datasheet for this
integrated circuit (IC) indicates that there are certain paths between its associated components that
need to be as short and low resistance as possible; otherwise, instability will result. There are also
some fairly large currents flowing here. Figure 9-5 shows the relevant part of the datasheet indicating
the paths that need to be kept as short as possible.
