Altera Cyclone II PowerPlay Early Power Estimator - Manual (Page 18)

3–2 Altera Corporation
PowerPlay Early Power Estimator User Guide For Cyclone II FPGAs May 2006
PowerPlay Early Power Estimator Spreadsheet Inputs
Table 3–1 describes the values that need to be specified in the Main
section of the PowerPlay Early Power Estimator spreadsheet.
Table 3–1. Main Section Information
Input Parameter Description
Device Select the appropriate Cyclone II device.
Package Select the appropriate package. The package options are dependant on the device
selected.
Temperature Grade Select whether a commercial or industrial device is being used.
Power Characteristics Select whether you would like to estimate typical or maximum power for the design.
Ambient Temp, T
A
(°C) Enter the ambient temperature the device will be operating at. This value can range
from –40 °C to 100 °C.
Airflow Select an ambient airflow from the options of still air, 100 linear feet per minute (lfm,
0.5 m/s), 200 lfm (1 m/s), or 400 lfm (2 m/s).
Heat sink Select the heat sink being used. You can specify no heat sink, a heat sink with set
parameters or specify a custom solution. The heat sink selection will update the
θ
SA
Heatsink-Ambient parameter under Thermal Analysis. If a custom solution is
selected the value will be what is entered for Custom
θ
SA
(°C/W).
Custom θ
SA
(°C/W) Enter a value for a custom heat sink setting. This value is only used if you set the
Heat Sink parameter to “Custom Solution.”
Board Thermal Model Select the type of board to be used in thermal analysis. If no heat sink has been
selected, the Altera-provided
θ
JA
value includes the board thermal pathway. If a
board thermal model is selected, you must enter a board temperature in the Board
Temp field. This field is only available when Auto Compute T
J
is selected.
Board thermal resistance is a function of device package, number of signal and
power layers, % metallization at each layer, inter-layer thickness, and many other
parameters.
θ
JB
values for a typical customer board stack (based on selected
device and package) are provided for estimation purposes.
Users should perform a detailed thermal simulation of their system to determine
final junction temperature. This two-resistor thermal model is for early estimation
only.
Custom
θ
JB
(°C/W) Enter the junction-to-board thermal resistance obtained from thermal simulation if
Custom is selected under Board Thermal Model. This field is only available when
Auto Compute T
J
is selected.
Board Temp, T
B
(°C) Enter the temperature on the PCB at the back-side of the device. This temperature
is combined with the
θ
JB
value of the board to compute the junction temperature for
the FPGA. This field is only available when Auto Compute T
J
is selected.
If the entered board temperature is less than ambient, the tool assumes ambient
temperature in its thermal analysis since it is not possible for the board to be below
ambient. Similarly, board temperatures in excess of the computed junction
temperature are capped to the junction temperature.