47
2467S–AVR–07/09
ATmega128
Standby Mode
When the SM2..0 bits are 110 and an External Crystal/Resonator clock option is selected, the
SLEEP instruction makes the MCU enter Standby mode. This mode is identical to Power-down
with the exception that the Oscillator is kept running. From Standby mode, the device wakes up
in 6 clock cycles.
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
Table 18.
Active Clock Domains and Wake Up Sources in the Different Sleep Modes
Active Clock Domains
Oscillators
Wake Up Sources
Sleep
Mode
clk
CPU
clk
FLASH
clk
IO
clk
ADC
clk
ASY
Main Clock
Source
Enabled
Timer
Osc
Enabled
INT7:0
TWI
Address
Match
Timer
0
SPM/
EEPROM
Ready
ADC
Other
I/O
Idle
X
X
X
X
X
X
X
X
X
X
ADC
Noise
Reduction
X
X
X
X
X
X
X
X
Power-
down
X
X
Power-
save
X
X
Standby
X
X
X
Extended
Standby
X
X
X
