Altera PowerPlay Early Power Estimator - Manual (Page 40)

3–28 Chapter 3: Using Cyclone III PowerPlay Early Power Estimator
Factors Affecting PowerPlay Early Power Estimator Accuracy
PowerPlay Early Power Estimator User Guide for Cyclone III FPGAs © June 2009 Altera Corporation
For example, location 3 is where the ambient temperature pertaining to the device
should be obtained for input into the PowerPlay Early Power Estimator. Location 1
and 2 are cooler than location 3, and location 4 is likely close to 25°C. Temperatures
close to devices in a system are often in the range of 50 to 60°C, but the values can
vary significantly. In order to obtain accurate power estimates from the PowerPlay
Early Power Estimator, you must get a realistic estimate of the ambient temperature
near the FPGA device.
Heat Sink
When using a heat sink, the power is determined by the following two equations.
P = (T
J
- T
A
) / 
JA

JA
= 
JC
+ 
CS
+ 
SA
The value 
JC
is specific to the FPGA and can be obtained from the data sheet. The
value 
CS
refers to the material that binds the heat sink to the FPGA and is
approximated to be 0.1 C/W. The value 
SA
is obtained from the manufacturer of the
heat sink. You must ensure that the value obtained is for the right conditions for the
FPGA, which include analyzing the correct heat sink information at the appropriate
airflow at the device.
f For more information about how to determine heat sink information, refer to
AN 358: Thermal Management for 90-nm FPGAs . The information contained in the
application note is also applicable to 65-nm FPGAs.