
45
ATmega64A [DATASHEET]
8160D–AVR–02/2013
10.6
Extended Standby Mode
When the SM2:0 bits are 111 and an external crystal/resonator clock option is selected, the SLEEP instruction
makes the MCU enter Extended Standby mode. This mode is identical to Power-save mode with the exception that
the Oscillator is kept running. From Extended Standby mode, the device wakes up in six clock cycles.
Notes:
1. External Crystal or resonator selected as clock source.
2. If AS
0 bit in ASSR is set.
3. Only INT3:0 or level interrupt INT7:4.
10.7
Minimizing Power Consumption
There are several issues to consider when trying to minimize the power consumption in an AVR controlled system.
In general, sleep modes should be used as much as possible, and the sleep mode should be selected so that as
few as possible of the device’s functions are operating. All functions not needed should be disabled. In particular,
the following modules may need special consideration when trying to achieve the lowest possible power
consumption.
10.7.1
Analog to Digital Converter
If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should be disabled before entering
any sleep mode. When the ADC is turned off and on again, the next conversion will be an extended conversion.
10.7.2
Analog Comparator
When entering Idle mode, the Analog Comparator should be disabled if not used. When entering ADC Noise
Reduction mode, the Analog Comparator should be disabled. In the other sleep modes, the Analog Comparator is
automatically disabled. However, if the Analog Comparator is set up to use the internal voltage reference as input,
the Analog Comparator should be disabled in all sleep modes. Otherwise, the internal voltage reference will be
the Analog Comparator.
Table 10-1.
Active Clock Domains and Wake Up Sources in the Different Sleep Modes
Active Clock Domains
Oscillators
Wake Up Sources
Sleep
Mode
clk
CP
U
clk
FLASH
clk
IO
clk
AD
C
clk
AS
Y
Main
Cl
o
c
k
Source
Enab
led
Timer
Osc
Enab
led
I
N
TW
I
Ad
dress
Match
Timer0
SPM/
EEPR
OM
R
eady
A
Other
I/O
Idle
X
XX
X
ADC
Noise
Reduction
XX
X
XX
X
Power-
down
X
Power-
save
X
Extended