Altera PowerPlay Early Power Estimator - Manual (Page 66)

3–48 Altera Corporation
PowerPlay Early Power Estimator For Stratix II, Stratix II GX & HardCopy II January 2007
Power Analysis
Figure 3–36. Heat Sink (Top View)
The considerations above can heavily influence the airflow seen at the
device. When entering information into the PowerPlay Early Power
Estimator spreadsheet, it is necessary to consider these implications in
order to get an accurate airflow value. It is the designer's responsibility to
determine the actual airflow at the FPGA and correctly input this value
into the PowerPlay Early Power Estimator spreadsheet.
Temperature
The PowerPlay Early Power Estimator spreadsheet requires you to enter
the ambient air temperature for the device in order to calculate the device
thermal information correctly. Ambient temperature refers to the
temperature of the air around the device. This is almost always much
higher than the ambient temperature outside of the system. To get an
accurate representation of ambient temperature for the device, the
temperature must be measured as close to the device as possible. This can
be done with a thermocouple.
Entering the incorrect ambient air temperature could drastically alter the
power estimates in the PowerPlay Early Power Estimator spreadsheet.
The figure below illustrates a simple system with the FPGA housed in a
box.
In this case, the temperature is very different at each of the numbered
locations illustrated in
Figure 3–37 .
F
A
N Heat Sink Fins