Rapid technological advances in computer and signal processing electronics
packaging, utilizing large-scale integrated (LSI) circuits, very-large-scale
integrated (VLSI) circuits and very-high-speed integrated circuits (VHSIC) have
resulted in significant reductions in the volume required to implement complex
electronic functions. The technological advances have not been as great in power
supply electronics. Reliable power supplies with power densities of 1 to 6 watts
per cubic inch will not satisfy the need of sophisticated systems now being
designed, much less those in the near future.
System volume required for the power supply is a
function of both the system thermal density and the output power density of
the power supply. Figure 3-4 presents a graphic illustration of the percentage
of system volume required by the power supply for various system load
densities. As the system thermal density increases, it is obvious that the
power supply density must also increase to avoid a condition where the
majority of the system volume is occupied by the power supply. The following
is the methodology for using Figure 3-4 in conjunction with the worksheet in
when system volume
and power are known.
Step 1: Select System Load Density Curve.
Step 2: Determine Power Supply Volume as a percentage of System Volume
System Volume - Load Volume
------------------------------------------ X 100
Total System Volume
Step 3: Locate Power Supply Output Density from the intersection of the
"Supply % of System Volume" with the selected System Load Density Curve.
Step 4: Compare the determined Power Supply Density
with Calculation from Appendix
to assess effort/risk.
If the results are unacceptable, perform tradeoffs and