Logic Design for Array-Based Circuits
by Donnamaie E. White
Copyright © 1996, 2001, 2002 Donnamaie E. White
Last Edit July 22, 2001
Step 10: Determine ECL Static Power PEO
The equation used by the AMCC MacroMatrix ERC software to compute ECL static power dissipation for ECL outputs is:
The 1.3V term represents the average between VOH and VOL. This is considered to be the statistical worst-case for this function
If there is more than one termination, the power for each type of termination is computed and summed to find the total PECL outputs
ECL Output Termination Current
Table 7-15 provides the ECL output termination currents used by the AMCC MacroMatrix ERC software. The currents shown are the average current (average of IOH and IOL)
AMCC automated ECL static power is computed with the 50 or 25 ohm termination under the assumption of 50% terminations active. This is because AMCC provides macros that drive 50 ohm loads and macros that drive 25 ohm loads. These assumptions may vary with the vendor.
Table 7-15 ECL Termination Current
* the average current (average of IOH and IOL) for termination to -2V
* When 50 ohm or 25 ohm Terminations are Not Used
Resistive loads that differ from that used by automation software will require manual computation. These loads should be identified when performing design submission to any vendor.
If other ECL output load resistances are used, the actual current value must be computed for use in the ECL static power equation. For a -2V termination, to find the average current in mA, use the following equation.
* When VT Ê -2V
For other termination voltages, an adjustment to the power dissipation computation must be made by the designer. For a termination voltage VT, to find the average current in mA, use the following equation.
* Darlington ECL Outputs
Darlington ECL outputs are treated as a standard ECL outputs for static power computations.
* On-Chip Series Termination
There is no IOEF output current for on-chip series termination ECL output macros. All current (power) dissipated is specified in the macro docu-mentation.
Step 11: Sum the Result - Total DC power
Sum the results of the macro and overhead current power computations with any ECL output macro static power dissipation to obtain the total worst-case DC power dissipation for the circuit:
The result is the total worst-case DC power dissipated by the circuit on the target array.
Copyright @ 2001,
2002 Donnamaie E. White, White