Atmel XMEGA-A1 Xplained Evaluation Board ATAVRXPLAIN ATAVRXPLAIN Hoja De Datos

 

8267B-AVR-12/10 

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. 

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. 

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. 

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.