Altera PowerPlay Early Power Estimator - Manual (Page 15)

Input Parameter Description
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 if
you turn on the following options:
• Auto Computed T
J
• Estimated Theta J
A
• Set the Heat Sink parameter to Custom
To compute the overall junction-to-ambient resistance through
the top of the device, the Custom θ
SA
parameter is combined with
a representative case-to-heatsink resistance and an Altera-
provided junction-to-case thermal resistance.
Board Thermal Mode
Select the type of board that is used in the thermal analysis. The
value is None (Conservative), Typical Board, or JEDEC (2s2p).
This field is only available if you turn on the Auto Computed T
J
and Estimated Theta J
A
options.
If you select None (Conservative), the thermal model assumes no
heat is dissipated through the board, resulting in a pessimistic
calculated junction temperature. This option is not available if the
Heat Sink option is set to None.
If you select Typical Board, the thermal model assumes the
characteristics of a typical customer board stack, which is based on
the selected device and package.
If you select JEDEC (2s2p), the thermal model assumes the
characteristics of the JEDEC 2s2p test board specified in standard
JESDEC51–9.
To determine the final junction temperature, Altera recommends
performing a detailed thermal simulation of your system. This
two-resistor thermal model is only for early estimation.
Thermal Power
Thermal power is the power dissipated in the device. Total thermal power is a sum of the thermal power
of all the resources used in the device, including the maximum power from standby and dynamic power.
Total thermal power only includes the thermal component for the I/O section and does not include the
external power dissipation, such as from voltage-referenced termination resistors.
The static power (P
STATIC
) is the thermal power dissipated on chip, independent of user clocks. P
STATIC
includes the leakage power from all FPGA functional blocks, except for I/O DC bias power and
transceiver DC bias power, which are accounted for in the I/O and transceiver sections.
P
STATIC
is the only thermal power component which varies with junction temperature, selected device,
and power characteristics (process).
The following figure shows the total thermal power (W) and P
STATIC
consumed by the FPGA and hard
processor system (HPS). The thermal power for each worksheet is displayed. To see how the thermal
power for a worksheet was calculated, click on the button to view the selected worksheet.
UG-01070
2015.01.20
Thermal Power 3-5
PowerPlay Early Power Estimator Worksheets Altera Corporation
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