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
Peripheral Active in Sleep Mode
Idle Standby Power-Down
CPU - - -
RTC X X(1,2) X(2)
WDT X X X
BOD X X X
EVSYS X X X
CCL X X(1) -
ACn X X(1) -
ADCn X X(1) -
DACn X X(1) -
TCBn X X(1) -
All other peripherals X - -
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 Source Active in Sleep Mode
Idle Standby Power-Down
Main clock source X X(1) -
RTC clock source X X(1,2) X(2)
WDT oscillator X X X
BOD oscillator(3) X X X
CCL clock source X X(1) -
TCD clock source X - -
Note:
  1. For the clock source to run in Standby sleep mode, the RUNSTDBY bit of the requesting 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 Sources Active in Sleep Mode
Idle Standby Power-Down
PORT Pin interrupt X X X(1)
BOD VLM interrupts X X X
RTC interrupts X X(2,3) X(3)
TWIn Address Match interrupt X X X
USARTn Start-of-Frame interrupts X X -
ADCn interrupts X X -
TCBn Capture interrupt X X -
All other interrupts X - -
Note:
  1. The I/O pin must be configured according to Asynchronous Sensing Pin Properties in the PORT section.
  2. For the peripheral to run in Standby sleep mode, the RUNSTDBY bit of the corresponding peripheral must be set.

  3. 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.