Article ID: 000076070 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Why does the “Reg Outputs” column on the DSP sheet affect thermal power in EPE version 3.0 but not in EPE version 5.1 and newer?



In the EPE version 3.0 block thermal power in the DSP sheet was dependent on “Reg Outputs”.  But in the EPE version 5.1 block thermal power in the DSP sheet is independent of “Reg Outputs.  This was intended in order to reflect silicon measurements.

Altera's findings showed that the use of output registers had a negligible effect on DSP block thermal power.  And because the EPE predictions for block thermal power were sufficient to cover power usage with output registers either on or off, EPE version 5.1 was updated to make block thermal power independant of output registers.

Additionally, Altera's correlation activity showed that using the input and pipeline registers causes the DSP block to use significantly less power because they eliminate glitches by causing the signals to change simultaneously and only once per clock cycle. As such, the EPE reflects input and pipeline registers effect on power.

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