This section covers the most impressive components I have come across, all with extremely low power consumption. In reality, for most ultra-low power applications, you really don’t need to go this far. If you are using a rechargeable battery, the self discharge will be multiple orders of magnitude higher than the power consumption of these components. But, if you need to hit a very low power spec, consider these parts.

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Microcontrollers

The first thing to note is that it is very difficult to compare microcontrollers to each other and determine which one is lower power without knowing the application. Many microcontrollers designed for ultra-low power have a wide variety of power saving features, some of which are applicable, while others are not. This section will not compare the microcontrollers to each other, but rather will point out some useful features to consider

Texas Instruments MSP430

The TI MSP430 family is commonly known for its ultra-low power performance. The family has a wide selection, many of which are tuned for a given application. There is not enough time to dig into many of them, but I will focus on one example, the MSP430FR2355:

• 142uA/MHz in active mode
• Uses FRAM for memory, which can be overwritten effectively indefinitely and is non-volatile
• 42nA in shutdown (LPM4.5) mode with I/O wakeup
• 620nA in LPM3.5 with RTC running
• Minimal current variation over temperature

Microchip ATSAML21

A close cousin to the Arduino-compatible SAMD21, the SAML21 has a 32-bit ARM Cortex-M0+ core and a wide variety of useful low power features.

• Can run in active mode at 4MHz at 285uA 
• Down to 35uA/MHz in active mode
• ~1.2uA in standby mode with all SRAM maintained and RTC running
• ~530nA in backup mode with RTC running

ST STM32L4

The STM32L4 family of low power microcontrollers have an ARM Cortex-M4 core with FPU and a number of low power features.

• 84uA/MHz in active mode
• 8nA in shutdown mode with I/O wakeup
• 280nA in standby mode with RTC

Ambiq Apollo 3

The Ambiq Apollo 3 is used within Sparkfun’s Artemis platform. They have ARM Cortex-M4 cores with FPU, as well as BLE wireless communication.

• 6uA/MHz in active mode (though typically locked at 48MHz operation)
• 1uA in deep sleep with RTC

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Voltage Regulators

Texas Instruments TPS63900

The TPS63900 is an ultra-low power buck-boost regulator with very low quiescent current and high efficiency across a wide range of current output.

• 75nA quiescent current
• >90% efficient at 10uA
• >80% efficient from 1uA-400mA output

Microchip MCP1810

The MCP1810 is an ultra-low power LDO regulator with very low quiescent current.

• 20nA quiescent current
• 1nA shutdown current

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Sensors

Analog Devices ADXL362

The ADXL362 is an ultra-low power accelerometer with very low power performance compared to its competitors. Note however, that its accuracy and bias are relatively poor.

• 1.8uA at 100Hz data sampling
• 270nA on “wake-on-shake” mode with ~6Hz sampling

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Others

Micro Crystal Switzerland RV-3028-C7

The RV-3028-C7 is a RTC module with an I2C interface, extremely low power consumption, and high accuracy.

• +-1ppm @ 25C
• 45nA @ 3V