Altera Cyclone II PowerPlay Early Power Estimator Bedienungsanleitung PDF herunterladen (Seite 44)

3–28 Altera Corporation

PowerPlay Early Power Estimator User Guide For Cyclone II FPGAs May 2006

Power Analysis

the case, thermal interface material and heat sink is referred to as the

junction-to-ambient thermal resistance (θ

). Figure 3–25 shows the

thermal model for the PowerPlay Early Power Estimator spreadsheet.

Figure 3–25. Thermal Model for EPE with a Heat Sink

If you want the PowerPlay Early Power Estimator spreadsheet thermal

model to take the junction-to-board thermal resistance (θ

) into

consideration, set the Board Thermal Model to either “Typical” or

“Custom.” A Typical board thermal model sets θ

to a value based on the

package and device selected. If you choose a Custom board thermal

model, you must specify a value for θ

. If you do not want the PowerPlay

Early Power Estimator spreadsheet thermal model to take the θ

resistance into consideration, set the Board Thermal Model to “None

(conservative).” In this case, the path through the board is not considered

and for power dissipation and a more conservative thermal power

estimate is obtained.

The junction-to-ambient thermal resistance (θ

) is determined by the

addition of the junction-to-case thermal resistance (θ

), the case-to-heat

sink thermal resistance (θ

) and the heat sink-to ambient thermal

resistance (θ

= θ

+ θ

Based on the device, package, airflow, and the heat sink solution selected

in the main input parameters, the PowerPlay Early Power Estimator

spreadsheet determines the junction-to-ambient thermal resistance (θ

Power (P) Power (P)

Heat Source

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Altera Cyclone II PowerPlay Early Power Estimator Bedienungsanleitung Seite 44