AVR1010 Datasheet, PDF (2/13 Pages) ATMEL Corporation – Minimizing the power consumption of Atmel AVR XMEGA devices

2 Reducing the power consumption to a minimum
Though many factors affect the power consumption, some will naturally affect more
than others. Listed below are the most important factors, with recommendations and
considerations.
2.1 Operating voltage
The power consumption is proportional to the square of the device’s supply voltage,
which should therefore be kept as low as possible.
A reduction in supply voltage can lower the limit for the maximum system clock
frequency, thus increasing the time required in ACTIVE mode to execute a given
amount of code.
Minimize power consumption by using as low supply voltage as possible.
2.2 Active mode operation
In ACTIVE mode, i.e. when sleep modes are not used, the power consumption is
proportional to the system clock frequency. This means that if sleep modes are not
used, the device should be run at the lowest possible system clock frequency to
minimize the power consumption.
Minimize power consumption by keeping the clock frequency as low as possible if
sleep modes are not used.
2.3 Sleep modes
In most applications it is desirable to minimize the power consumption, but not to
reduce the system clock frequency – mainly to ensure fast processing and quick
response of the system/product. In such applications one can use the “sleep modes”
of the Atmel^® AVR^® XMEGA^® to put the device in a low power state when there is
nothing to process. The main principle is then to run as fast as possible, and sleep as
much as possible. Running as fast as possible reduces the effect of static power
consumption (i.e. independent of clock frequency), e.g. due to non-volatile memory
being enabled in ACTIVE mode.
The power consumption and operation of peripherals in sleep depends on which
sleep mode is used. Table 2-1 shows the characteristics of the different sleep modes
available for XMEGA devices. An application may switch between sleep modes
during operation, depending on which mode is the most suitable at the time.
2 _AVR1010
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