Altera PowerPlay Early Power Estimator - Manual (Page 17)

Altera Corporation 3–3
May 2008 PowerPlay Early Power Estimator For Arria GX FPGAs
Using the PowerPlay Early Power Estimator
Heat Sink Select the heat sink being used. You can specify no heat sink, a custom solution, or
specify a heat sink with set parameters. This field is only available when you select
Auto Computed T
J
.
Representative examples of heat sinks are provided: larger heat sinks provide lower
thermal resistance, and thus lower junction temperature. If the heat sink is known,
consult the datasheet and enter a custom heatsink-to-ambient value according to the
airflow in your system.
The heat sink selection updates
θ
SA
and the value is seen in the Custom
θ
SA
(°C/W)
parameter. If you select a custom solution, the value is what is entered for Custom θ
SA
(°C/W).
Airflow Select an available ambient airflow in linear-feet per minute (lfm) or meters per
second (m/s). The options are 100 lfm (0.5 m/s), 200 lfm (1.0 m/s), 400 lfm (2.0 m/s),
or still air. This field is only available when you select Auto Computed T
J
and
Estimated
θ
JA
.
Increased airflow results in a lower case-to-air thermal resistance, and thus lower
junction temperature.
Custom θ
JA
(°C/W) Enter the junction-to-ambient thermal resistance between the device and ambient air
(in °C/W). This field is only available when you select Auto Computed T
J
and
Custom
θ
JA
.
This field represents the increase between ambient temperature and junction
temperature for every Watt of additional power dissipation.
Custom
θ
SA
(°C/W) Enter the heatsink-to-ambient thermal resistance from the heat sink data sheet if you
select a custom heat sink. The quoted values depend on system airflow and may also
depend on thermal power dissipation. This field is only available when Auto
Computed T
J
, Estimated
θ
JA
, and if you set the Heat Sink parameter to Custom
Solution.
The Custom
θ
SA
parameter is combined with a representative case-to-heatsink
resistance and an Altera provided junction-to-case resistance to compute overall
junction-to-ambient resistance through the top of the device.
Table 3–1. Main Section Information (Part 2 of 3)
Input Parameter Description