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Electrical

There are still several tasks that need to be considered regarding the electrical needs of the CPU board. A suitable power supply needs to be purchased or designed. This power supply needs to supply a current of 4 amps at a voltage of +5V ($ \pm 5\%$). This requirement on the power supply excludes using a linear supply as the power dissipation would be too great:
Assuming a worst case battery voltage of +14V.

\begin{displaymath}
\begin{split}
P&=IV\\
P&=4A \cdot (14V-5V)\\
P&=36W\\
\end{split}
\end{displaymath}

We would need to dissipate 36W of power in the liner regulator, so for this application a high efficiency switching regulator. National semiconductors produces a line of ``simple switcher" regulators that require few external components to design such a power supply. The task of designing this power supply will occur after the platform has been assembled and tested, as code development can begin without it by simply using a standard PC power supply.

Jordan Reynolds 2003-05-29