Altera PowerPlay Early Power Estimator - Manual (Page 39)

Altera Corporation 3–21
January 2007 PowerPlay Early Power Estimator For Stratix II, Stratix II GX & HardCopy II
Using the PowerPlay Early Power Estimator
Clock Freq (MHz) Enter the clock frequency (in MHz). This value must be in the range of 0 to 1040 MHz.
100 MHz with a 12.5% toggle means that each I/O pin toggles 12.5 million times per
second (100 × 12.5%).
# Output Pins Enter the number of output pins used in this module. A differential pair of pins should
be considered as one pin.
# Input Pins Enter the number of input pins used in this module. A differential pair of pins should be
considered as one pin.
# Bidir Pins Enter the number of bidirectional pins used in this module. The I/O pin is treated as an
output when its output enable signal is active and an input when the output enable is
disabled.
An I/O configured as bidirectional but used only as an output consumes more power
than one configured as an output-only, due to the toggling of the input buffer every time
the output buffer toggles (they share a common pin).
I/O Bank Select the I/O bank that the module is located in. If you do not know which I/O bank
the pins are assigned to, leave the value as “?.” Assigning the I/O module to a bank
checks whether or not your I/O voltage assignments are compatible. This allows
per-bank I
CCIO
reporting.
The PowerPlay Early Power Estimator spreadsheet does not take any I/O placement
constraints into consideration except if the I/O bank, I/O standard, I/O voltage are
compatible.
Toggle % Enter the average percentage of output and bidirectional pins toggling on each clock
cycle. The toggle percentage ranges from 0 to 200%. If the pin uses a double data rate
(DDR), you can set the data rate to single data rate (SDR) and double the toggle
percentage. The Quartus II software often uses this method to output information.
Typically the toggle percentage is 12.5%. To be more conservative, you can use a
higher toggle percentage.
OE % Enter the average percentage of time that:
● The output I/O pins are enabled.
● Bidirectional I/O pins are outputs and enabled.
During the remaining time:
● Output I/O pins are tristated.
● Bidirectional I/O pins are inputs.
This number must be a percentage between 0% and 100%.
Load (pF) Enter the pin loading external to the chip (in pF). Only applies to outputs and
bidirectional pins. Pin and package capacitance is already included in I/O model.
Therefore, you only need to include off-chip capacitance in the Load parameter.
Table 3–6. I/O Module Information in the I/O Section (Part 2 of 3)
Column Heading Description