ATXMEGA128A4 Datasheet, PDF (19/69 Pages) ATMEL Corporation – 8/16-bit XMEGA A4 Microcontroller

XMEGA A4
11. Power Management and Sleep Modes
11.1 Features
11.2 Overview
• 5 sleep modes
– Idle
– Power-down
– Power-save
– Standby
– Extended standby
• Power Reduction registers to disable clocks to unused peripherals
The XMEGA A4 provides various sleep modes tailored to reduce power consumption to a mini-
mum. All sleep modes are available and can be entered from Active mode. In Active mode the
CPU is executing application code. The application code decides when and what sleep mode to
enter. Interrupts from enabled peripherals and all enabled reset sources can restore the micro-
controller from sleep to Active mode.
In addition, Power Reduction registers provide a method to stop the clock to individual peripher-
als from software. When this is done, the current state of the peripheral is frozen and there is no
power consumption from that peripheral. This reduces the power consumption in Active mode
and Idle sleep mode.
11.3 Sleep Modes
11.3.1 Idle Mode
11.3.2
In Idle mode the CPU and Non-Volatile Memory are stopped, but all peripherals including the
Interrupt Controller, Event System and DMA Controller are kept running. Interrupt requests from
all enabled interrupts will wake the device.
Power-down Mode
11.3.3
In Power-down mode all system clock sources, and the asynchronous Real Time Counter (RTC)
clock source, are stopped. This allows operation of asynchronous modules only. The only inter-
rupts that can wake up the MCU are the Two Wire Interface address match interrupts, and
asynchronous port interrupts, e.g pin change.
Power-save Mode
11.3.4
Power-save mode is identical to Power-down, with one exception: If the RTC is enabled, it will
keep running during sleep and the device can also wake up from RTC interrupts.
Standby Mode
Standby mode is identical to Power-down with the exception that all enabled system clock
sources are kept running, while the CPU, Peripheral and RTC clocks are stopped. This reduces
the wake-up time when external crystals or resonators are used.
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