Chapter 17: Understanding and Evaluating Power in MAX II Devices
17–15
Power Saving Techniques
Table 17–8. Thermal Analysis Information
Column Heading
Description
Junction Temp, TJ (°C)
θJA Junction-Ambient
Represents the estimated device junction temperature.
Represents the junction-to-ambient thermal resistance through the top of the device
(°C/W).
Maximum Allowed TA (°C)
Represents a guideline for the maximum ambient temperature (°C) that the device can
be subjected to without violating maximum junction temperature.
Power Supply Current
The power supply current provides the estimated current consumption for power
supplies. The ICCPOWERUP is only applicable during power up when the configuration
flash memory (CFM) block downloads to the SRAM. The ICCINT current is the supply
current required from VCCINT. The total ICCIO current is the supply current required from
V
CCIO for all I/O banks. For estimates of ICCIO based on I/O banks, refer to the “I/O
Section” on page 17–8 of the PowerPlay Early Power Estimator spreadsheet.
Figure 17–16 shows the Power Supply Current section.
Figure 17–16. Power Supply Current
Table 17–9 describes the Power Supply Current parameters of the PowerPlay Early
Power Estimator spreadsheet.
Table 17–9. Power Supply Current Information
Column Heading
ICCPOWERUP
ICCINT
ICCIO
Description
Represents the maximum current drawn during power-up.
Represents the total current drawn from the ICCINT supply.
Represents the total current drawn from the ICCIO power rail(s). Refer to the
“I/O Section” on page 17–8 for details about the current drawn from each
I/O rail.
Power Saving Techniques
The following guidelines reduce power consumption for an application:
■
Slow the operation in portions of the circuit. ICC is proportional to the frequency of
operation. Slowing parts of a circuit lowers the ICC and therefore reduces the
power. MAX II devices provide global or array clock source for all registers.
Signals that do not require high-speed operation can use a slower array clock that
reduces the system power consumption.
■
Reduce the number of outputs. Standby and dynamic current are required to
support all I/O pins on the device. Reducing the number of I/O pins can reduce
current necessary for the device, and thereby reduce the power.
© October 2008 Altera Corporation
MAX II Device Handbook
ALTERA [ ALTERA CORPORATION ]
