Altera PowerPlay Early Power Estimator - Manual (Page 18)

3–4 Altera Corporation
PowerPlay Early Power Estimator For Arria GX FPGAs May 2008
PowerPlay Early Power Estimator Inputs
Figure 3–1 shows the Main section of the PowerPlay Early Power
Estimator.
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 you select Auto Computed T
J
and Estimated
θ
JA
.
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.
You 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 you
select Auto Computed T
J
and Estimated
θ
JA
.
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 you select Auto Computed T
J
and Estimated
θ
JA
.
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.
Table 3–1. Main Section Information (Part 3 of 3)
Input Parameter Description