Altera PowerPlay Early Power Estimator - Manual (Page 39)

Altera Corporation 3–23
October 2005 PowerPlay Early Power Estimator User Guide: Stratix, Stratix GX & Cyclone FPGAs
Using PowerPlay Early Power Estimator for Stratix, Stratix GX & Cyclone FPGAs
total P
INT
, total P
IO
, P
TRANSCEIVER
(for Stratix GX devices only), and total
PowerPlay early power estimator are also displayed in the Device section
at the top of the PowerPlay early power estimator.
Thermal Analysis
In the Thermal Analysis section, enter the device’s ambient temperature
(T
a
) in degrees Celsius. T
j
is the maximum recommended operating
junction temperature based on the temperature grade of the device you
choose. The required junction-to-ambient thermal resistance (
θ
JA
) is the
minimum
θ
JA
for the ambient temperature you entered and the amount
of power your design consumes. The required
θ
JA
must be greater than
the
θ
JA
for the chosen device and package.
Based on the device and package you selected in the Device section, the
PowerPlay early power estimator determines the junction-to-case
thermal resistance (
θ
JC
) and
θ
JA
at still air and air flow rates of 100, 200,
and 400 LFpM. These numbers are obtained from the Altera Device
Package Information Data Sheet.
The maximum allowable power (P
MAX
) is calculated based on the device
package chosen and the ambient temperature using the following
equation:
(T
j
- T
a
) /
θ
JA
= P
MAX
The P
MAX
is reported for still air and air flow rates of 100, 200, and
400 LFpM. If the calculated power of your design is greater than the P
MAX
for the chosen device and package, you need to take the appropriate
thermal measures by adding a heat sink or cooling fan on your board.
If you are not using a heat sink, refer to the Without Heat Sink section of
the PowerPlay early power estimator, which displays whether your
selected device package
θ
JA
is less than the required
θ
JA
of your design at
still air or with airflow. “Good” indicates that the package
θ
JA
is less than
the minimum required
θ
JA
for your design. A blank result indicates that
the package θ
JA
is more than the minimum required θ
JA
. “No Value”
indicates that you have not completely entered the required information.
If you need to use a heat sink, you need to enter the case-to-heat sink
thermal resistance (
θ
CS
) and heat sink-to-ambient thermal resistance (
θ
SA
)
at still air and airflow rates of 100, 200, and 400 LFpM. The heat sink
manufacturer should specify these values. The results in the With Heat
Sink
section tells you whether your device package θ
JA
is less than the
required
θ
JA
at still air or with airflow when using a heat sink. A blank