11.3.2.1 Sleep Modes

In addition to Active mode, there are three different sleep modes with decreasing power consumption and functionality.

Idle
The CPU stops executing code. No peripherals are disabled, and all interrupt sources can wake the device.
Standby
The user can configure peripherals to be enabled or not, using the respective RUNSTBY bit. This means that the power consumption is highly dependent on what functionality is enabled, and thus may vary between the Idle and Power-Down levels.
SleepWalking is available for the ADC module.
Power-Down
BOD, WDT, and PIT (a component of the RTC) are active.
The only wake-up sources are the pin change interrupt, PIT, VLM, TWI address match, and CCL.
Table 11-1. Sleep Mode Activity Overview for Peripherals
PeripheralActive in Sleep Mode
IdleStandbyPower-Down
CPU
RTCXX(1,2)X(2)
WDTXXX
BODXXX
EVSYSXXX
CCLXX(1)
ACn
ADCn
TCBn
All other peripheralsX
Note:
  1. For the peripheral to run in Standby sleep mode, the RUNSTDBY bit of the corresponding peripheral must be set.

  2. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY bit to be set.
    In Power-Down sleep mode, only the PIT functionality is available.

Table 11-2. Sleep Mode Activity Overview for Clock Sources
Clock SourceActive in Sleep Mode
IdleStandbyPower-Down
Main Clock SourceXX(1)
RTC Clock SourceXX(1,2)X(2)
WDT OscillatorXXX
BOD Oscillator(3)XXX
CCL clock sourceXX(1)
Note:
  1. For the clock source to run in Standby sleep mode, the RUNSTDBY bit of the corresponding peripheral must be set.

  2. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY bit to be set.
    In Power-Down sleep mode, only the PIT functionality is available.

  3. The Sampled mode only.
Table 11-3. Sleep Mode Wake-Up Sources
Wake-Up SourceActive in Sleep Mode
IdleStandbyPower-Down
PORT Pin interruptXXX(1)
TWI Address Match interruptXXX
BOD VLM interruptXXX
CCL interruptsXX(2,3)X(3)
RTC interruptsXX(2,4)X(4)
USART interruptsX(5)X(6)-
TCAn interruptsXX(2)
TCBn interrupts
ADCn interrupts
ACn Compare interrupt
All other interruptsX--
Note:
  1. The I/O pin has to be configured according to Asynchronous Sensing Pin Properties in the PORT section.
  2. RUNSTDBY bit of the corresponding peripheral must be set to enter an active state.
  3. CCL can wake up the device if the path through LUTn is asynchronous (FILTSEL=0x0 and EDGEDET=0x0 in LUTnCTRLA register).
  4. In Standby sleep mode, only the RTC functionality requires the RUNSTDBY to be set to enter an active state. In Power-Down sleep mode, only the PIT functionality is available.
  5. Start-of-Frame interrupt is only available in Standby Sleep Mode.
  6. In Standby Sleep Mode only the Start-of-Frame interrupt will trigger Wake-Up from USART.