Logic Design for ArrayBased Circuitsby Donnamaie E. WhiteCopyright © 1996, 2001, 2002 Donnamaie E. White 


Power ConsiderationsLast Edit July 22, 2001 Case Study: DC Power ComputationThe Q20000 Series DC power methodology is detailed below to allow sample computations and to provide some reference for analysis of other arrays. The method can be modified to apply to all AMCC arrays, independent of their technology, and to apply to other vendor arrays Steps Required To Compute DC Power:  Example Array SeriesStep 1: Build the Macro Occurrence TableA macro occurrence table can be constructed before design capture to assist in the manual computation of interface current and power dissipation. A macro occurrence table should provide the data necessary to compute the worstcase DC power dissipated by the circuit. (This table approach can be used with macros that specify current or macros that specify power.)
AMCC MacroMatrix ERC power computations are done with the worststate current value, assuming the worst "state" always for those macros specified with HIGH and LOW or ENABLED and DISABLED current. The power dissipation value computed will be conservative. A manual computation can be made to adjust the current used for these statedependent macros Identify those macros where some assumption must be made on the value of the current to be used in the table. They will need to be identified during design submission Step 2: Find the Total Interface Macro CurrentThe macro current for individual interface macros is multiplied by the number of occurrences to determine the total typical current resulting from the use of that macro in the circuit. Change the labels if power has been specified Compute the total current used by all occurrences of each interface macro and sum these totals to find the total IEE and ICC interface current
IinterfaceEE = SUM INTERFACE MACROS IEE CURRENT Step 3: Compute the WorstCase Interface CurrentMultiply both sums by the worstcase current multiplier (WCCM1) for the interface macros to obtain the worstcase current due to interface macros
IinterfaceEEwc = WCCM1 * IinterfaceEE The Q20000 Series uses three worstcase current multipliers, one for core macros, one for interface macros and one for overhead current. Other arrays may be specified with one multiplier or may vary the multiplier or adjustment factor based on the product grade Table 712 Example WorstCase Current Multipliers


Copyright @ 2001,
2002 Donnamaie E. White, White
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