# Power Considerations

Last Edit July 22, 2001

Step 5: Compute AC Power For all ECL Input Macros

Using the counts from step 4, compute the AC power dissipated by the ECL inputs used in the circuit. For AMCC arrays, use:

PacI = f * n * 3.25 microwatts

where
f = frequency of operation in MHz
n = number of ECL input macros
conversion factor = 3.25 microwatt/macro-MHz for Q20000 Series

• Compute the AC power due to those input macros switching at the fastest frequency.
• Compute the AC power due to those macros switching at the next fastest frequency.
• Repeat until all ECL input macros are accounted for and sum the results.

Step 6: Find the Number of Internal Macros

Using the macro occurrence worksheet, find the number of internal macros. For AMCC customers, the number of internal macros can be determined from the AMCC Population ERC report.

Step 7: Compute AC Power For all Internal Macros

Using the count from step 6, estimate the AC power dissipated by the internal macros used in the circuit:

PacI = 0.20 * f * n * 3.25 microwatts

where
f = maximum frequency of operation in MHz
n = number of internal macros
0.2 = 20% switching
conversion factor = 3.25 microwatt/macro-MHz for Q20000 Series

Step 8: Sum All Components of AC Power

Sum the results together and convert to watts (or to the same units as was used for DC power). This equation provides an estimate of the worst-case AC power dissipation for the Q20000 array.

PdAC = PacI + Pacinternal + PacDARoutputs

Use the same equation for military and commercial computations.

Copyright @ 2001, 2002 Donnamaie E. White, White Enterprises
For problems or questions on these pages, contact dew@Donnamaie.com