1. To obtain the System Load Density in Watts per cubic inch, divide the
system power by the volume devoted to the load.

System Load Density = 680 / 1344 = 0.5 Watts per cubic inch.

2. Arbitrarily allocate 10% of the system volume for the power supply. Draw a
horizontal line (2A) from the Supply Volume axis to the intersection of the 0.5
Watts per cubic inch System Load Density curve.

3. Draw a vertical line (3A) from the intersection to the Supply Output Power
Density axis to determine the density as 4.6 Watts per cubic inch.

4. Referring to Example Number 1, the Power Density
Index is 4.6 + 1.75 correction factor = 6.35. This places the tentative design
in Region 4 of Figure
D-1 (extremely dense packaging with high risk). To reduce the risk a second
iteration may be made using a supply volume which is a greater percentage of the
system volume.

5. Allowing the power supply volume to be 25% of the
system volume, repeat steps 2 and 3 (depicted as 2B and 3B), obtaining 1.5
Watts per cubic inch for the Supply Output Power Density. The Power Density
Index is now reduced to 1.5 + 1.75 + 3.25, which placed the design in Region 2
of Figure
D-1
(moderate
packaging with low risk).

LV

6. Power Supply Volume = -------------------- x PSV

100 -
PSV

where LV = Load Volume in cubic inches and

PSV = Power Supply Volume as a
percent of System Volume

1344

Power Supply Volume = ------------------ x 25 = 448 cubic
inches

100 - 25

7. This 25% volume may be achieved with a 4" x 8" x 14" package which is
compatible with the 8" x 14" system load dimensions.