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7903A – AVR – 2006/02

Sleep Power Consumption Techniques Incorporated by picoPower

Technology

Sleep is often considered the most important low power mode, particularly in applications

that spend the majority of their time active. Atmel’s picoPower technology employs a

number of techniques that result in the lowest sleep mode power consumption of any

microcontroller on the market today.

True 1.8V Supply Voltage

The processes used in AVR MCUs support a power supply voltage range from 1.8V to

5.5V. The 1.8V operation is a true 1.8V operation. Which means that all the analog

modules, Flash, EEPROM and RAM run at 1.8V. True 1.8V operation ensures less power

consumption as the consumption is the sum of current and voltage as well as allowing the

battery supply to drop to 1.8V before being out of range.

Minimized Leakage Current

The temperature, the supply voltage and the process affect the leakage current. Atmel has

used proprietary processes that have been specifically developed for low power operation

based on years of research and experience. The leakage current of picoPower AVRs is

less than 100 nA.

Taking the BOD to the Sleeping BOD

Although zero-power brown-out detectors (BOD), such as that used in TI

save a lot of power, they are notoriously slow and can require a millisecond to detect a

below-threshold voltage. The slow response time could put the controller at risk. Atmel’s

AVR BOD detects brown-out conditions in 2 microseconds but draws about 20 uA, adding

substantially to the Power Down current of 100 nA.

As part of the picoPower technology, Atmel has maintained the high performance and

relatively high current of the BOD and saved power by simply turning it off when it is not

needed. This approach results in the lowest overall power consumption and the highest

possible performance with accurate detection at 1.8V, 2.7V and 4.5V. In addition to the

slow response time on the MSP430, there is some concern that its detection level is only

1.4V, substantially lower than the 2.2V required to have all the controller’s features

available.

Since there is no need for the BOD while the MCU is in the deep sleep mode, the

picoPower BOD can be turned off in Extended Standby, Standby, Power Save and Power

Down modes.

The picoPower BOD-disable feature is enabled by the application using a two-step secure

operation and is fully automatic. When entering sleep, the BOD is disabled after the MCU

has entered the sleep mode, and enabled to verify that the power supply is sufficient

before the MCU is allowed to wake from sleep. If the power supply is not sufficient, the

MCU will enter a reset mode before any code execution takes place.

While in sleep mode, the only critical parameters to handle are the RAM and register

contents. On AVR microcontrollers these contents are valid until ~0.3V Vcc, while the