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)X(2)
WDTXXX
BODXXX
EVSYSXXX
CCLXX(1)-
AC
ADC
TCB
All other peripheralsX--
Note:
  1. RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  2. PIT only.
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)X(2)
WDT oscillatorXXX
BOD oscillator(3)XXX
CCL clock sourceXX(1)-
Note:
  1. RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  2. PIT only.
  3. BOD oscillator runs only in Sampled mode.
Table 11-3. Sleep Mode Wake-Up Sources
Wake-Up SourcesActive in Sleep Mode
IdleStandbyPower-Down
PORT Pin InterruptXXX(1)
BOD VLM interruptXXX
RTC interruptsXX(2)X(3)
TWI Address Match interruptXXX
USART Start-of-Frame interrupt-X-
TCB interruptsXX(2)-
ADC interruptsXX(2)-
AC interruptsXX(4)-
All other interruptsX--
Note:
  1. The I/O pin must be configured according to Asynchronous Sensing Pin Properties in the PORT section.
  2. RUNSTBY bit of the corresponding peripheral must be set to enter the active state.
  3. PIT only.
  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.