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 1. Sleep Mode Activity Overview for Peripherals
Peripheral Active in Sleep Mode
Idle Standby Power-Down
CPU - - -
RTC X X(1) X(2)
WDT X X X
BOD X X X
EVSYS X X X
CCL X X(1) -
AC
ADC
TCB
All other peripherals X - -
Notes:
  1. 1.RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  2. 2.PIT only.
Table 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) X(2)
WDT oscillator X X X
BOD oscillator(3) X X X
CCL clock source X X(1) -
Notes:
  1. 1.RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  2. 2.PIT only.
  3. 3.BOD oscillator runs only in Sampled mode.
Table 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 interrupt X X X
RTC interrupts X X(2) X(3)
TWI Address Match interrupt X X X
USART Start-of-Frame interrupt - X -
TCB interrupts X X(2) -
ADC interrupts X X(2) -
AC interrupts X X(4) -
All other interrupts X - -
Notes:
  1. 1.The I/O pin must be configured according to Asynchronous Sensing Pin Properties in the PORT section.
  2. 2.RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  3. 3.PIT only.
  4. 4.When the RUNSTDBY bit is set, the AC will operate without updating its Status register or triggering interrupts. If another peripheral has requested CLK_PER, the AC will use the clock to update the Status register and trigger interrupts.
Parent topic: Operation