Low Power MCU

Low Power MCU

Low Power MCU

Embedded system design is very interesting topic major area of system design is cover in Embedded System Design Guide blog, but to design system with low power consumption & selectin of low power MCU is very challenging task, in this blog we are going to discuss on same.

Saving energy is beneficial for the environment and easier on the pocketbook. The myriad benefits of improving energy efficiency have well-documented: lower electric bills for consumers, reduced load on utilities, reduced cost of ownership for electronics products and few batteries thrown away in landfills.
As the use of electronic devices pervades virtually every aspect of our lives, reducing power consumption must start at the semiconductor. The power-saving techniques that are designed in at the chip level have a far-reaching impact. This is especially true with regard to the microcontrollers (MCUs) that serve as the intelligent engines behind a majority of today’s electronic devices.
From a systems architecture perspective, the challenge of identifying which MCUs truly are “low-power” requires designers to navigate the myriad claims made by various semiconductor vendors. Because of the different (and often confusing) metrics used by vendors, this simple task.

Total power consumed = Active mode power + Standby (sleep) mode power
However, another important metric to keep in mind is the amount of time it takes for an MCU to transition from a standby state into an a state. Since the MCU cannot do any useful processing until all of the digital and analog components are fully settled and operational, it important to add in this (wasted) power when calculating total power consumption:
Total power consumed = Active mode power + Standby (sleep) mode power + Wake-up power

Source: www.mouser.com/silabs

Switching-type converters may be a possible solution but they are best suited regulator environments requiring large voltage conversion ratios. However, for battery-type applications where the average voltage conversion ratio is small (approaching 1:1 at the end of the battery life), a better solution would be to add an on-chip low drop-out (LDO) linear voltage regulator since it can offer acceptable efficiency with lower complexity and cost than a switching solution.

Different factors affecting power consumptions of MCU’s

  • Switching Speed
  • Gate Current
  • Operating Voltage
  • Temperature
  • Operating modes of MCU

Comparing different MCU’s


ST’s ultra-low-power MCU platform is based on a proprietary ultra-low-leakage technology and optimized design.

STM32 ultra-low-power microcontrollers offer designers of energy-efficient embedded systems and applications a balance between performance, power, security and cost effectiveness. The portfolio includes the STM8L (8-bit proprietary core), the STM32L4 (Arm® Cortex®-M4), the STM32L0 (Arm® Cortex®-M0+) and the STM32L1 (Arm® Cortex®-M3). The STM32L5 MCU (Arm® Cortex®-M33) with its enhanced security features is the latest addition to this rich portfolio.

Achieving the industry’s lowest current variation (25 to 125 °C), STM8L/STM32L solutions guarantee outstanding low-current consumption at high temperatures. STM32L1 MCUs also feature the industry’s lowest power consumption of 170 nA in low-power mode with SRAM retention. Wake-up times are as low as 3.5 μs from stop mode.

The new STM32U5 series combines the latest and most efficient Arm Cortex-M33 core with an innovative 40 nm platform that reduces energy consumption to the bone, while increasing performance. The series also adds the state-of-the-art features which are required in today’s applications, including advanced cyber security with hardware-based protection, and graphics accelerators for rich graphical user interfaces.

The STM32L5 series enhanced security features leverage Arm® Cortex®-M33 and its TrustZone® for Armv8-M. Thanks to this new core and a new ST ART Accelerator™ (also supporting external memory), the STM32L5 reaches an 443 CoreMark.

The STM32L4 series offers the excellence of ST’s ultra-low power platform with an additional performance dimension by providing 100 DMIPS with DSP instructions and Floating-Point Unit (FPU), more memory (up to 1 Mbyte of Flash memory) and innovative features.

The STM32L4+ series extends STM32L4 technology by offering higher performance (120 MHz/409 CoreMark executing from internal Flash memory), larger embedded memories (up to 2 Mbytes of Flash memory and 640 Kbytes of SRAM), and rendering advanced graphics without compromising ultra-low-power consumption. The STM32L0 series offers a genuine energy-saving solution for entry-level applications. Available in tiny packages down to 14 pins and with a wide range of Flash memory densities from 8 to 192 Kbytes, the STM32L0 features ultra-low power consumption in a competitive portfolio.

Source: www.st.com

Minimizing power consumption in battery-powered  wearables, wireless sensor networks, and other Internet of Things (IoT)-enabled smart devices is essential. If you need to reduce the operating power in your project, discover how our 8-, 16- and 32-bit eXtreme Low Power (XLP) PIC® microcontrollers (MCUs), 8-bit AVR® and 32-bit SAM MCUs with picoPower® technology, and 32-bit low-power SAM microprocessors (MPUs) offer the right combination of features to meet your design’s specific requirements.

8-bit Low-Power MCUs

Low-Power Sleep Modes with Flexible Wake-Up Sources:

  • Sleep current down to 20 nA
  • Deep sleep current down to 9 nA
  • Low-power self-wake-up sources: special low-power Brown-out Reset (BOR), Power-on Reset (POR), Watchdog Timer (WDT), Real-Time Clock (RTC), INT, Asynchronous Master Clear Reset (MCLR)
  • Idle and Doze lower-power modes

Flexible and Advanced Integrated Peripherals:

  • 20+ Core Independent Peripherals (CIPs) to offload the CPU while enabling sensor interfacing, waveform control, timing/measurements, logic/math, safety/monitoring, communications and user interface functionality
  • Intelligent analog features include 12-bit Analog-to-Digital Converter with Computation (ADCC), op amps, comparators, Digital-to-Analog Converters (DACs) and more

Long Battery Life with Robust and Reliable Features

  • Enable battery lifetime of 20+ years
  • Low-power supervisors for safer operation (BOR, WDT)
  • Core Independent Peripherals (CIPs) perform tasks at lowest possible energy requirement
  • VBAT battery backup powered separately
  • Robustness in hostile environments
  • Low-power and robust touch sensing technologies

Large Portfolio and Efficient Performance Across Voltage Range

  • 6–100 pins
  • Up to 384 KB Flash
  • Up to 16 KB RAM
  • 1.6V to 5.5V operation
  • Wide selection of package options
  • Peripherals run autonomously in low-power modes

16-bit XLP MCUs

Low-Power Sleep Modes with Flexible Wake-Up Sources:

  • RAM retention sleep mode
  • Sleep current down to 30 nA
  • Deep sleep current down to 10 nA
  • Flexible self-wake-up sources: special low-power Brown-out Reset (BOR), Power-on Reset (POR), Watchdog Timer (WDT), Real-Time Clock/Calendar (RTCC), External Interrupts (INT), Asynchronous Master Clear Reset (MCLR)
  • Wake-up trigger from several peripherals

Flexible and Advanced Integrated Peripherals:

  • Core Independent Peripherals (CIPs) to offload the CPU such as Configurable Logic Cell (CLC), Real-Time Clock/Calendar (RTCC), Multiple Capture/Compare Pulse-Width Modulation (MCCP) and Peripheral Trigger Generator (PTG)
  • Integrated USB and LCD driver
  • Rich analog integration including 16-bit Sigma-Delta Analog-to-Digital Converters (ADCs), 12-bit Digital-to-Analog Converter (DAC) and op amps
  • Crypto engine for data security

Long Battery Life with Robust and Reliable Features

  • Enable battery lifetime of 20+ years
  • Low-power supervisors for safer operation (BOR, WDT)
  • Core Independent Peripherals perform complex tasks at lowest possible energy requirement
  • VBAT battery backup powered separately

Large Portfolio and Efficient Performance Across Voltage Range

  • 8–121 pins
  • 4 KB–1 MB Flash
  • Wide selection of packages
  • More than 80% of instructions are single cycle execution
  • Peripherals run autonomously in low-power modes

Benefits of 32-bit XLP PIC MCUs and SAM MCUs with picoPower®

Low-Power Sleep Modes and Operating Voltage

  • Active mode current down to 25 μA/MHz
  • Deep sleep current down to 100 nA
  • SRAM retention (40 KB) down to ~1 μA
  • 1.2 μs wake-up time from idle state
  • Fully operational down to 1.62V while still maintaining all functionality, including analog functions
  • Highest certified ULPMark™ score for any Arm Cortex-M23 or Arm Cortex- M0+ class device; SAM L11 MCU achieved ULPMark score of 410

Flexible and Advanced Peripherals

  • Event System for CPU-independent, inter-peripheral communication offloads and minimizes CPU active time
  • Sleepwalking with dynamic power gating allows MCU to be put into deep sleep and wake up only upon a pre-qualified event
  • Chip-level tamper resistance and Arm TrustZone® technology to protect low-power applications from security vulnerabilities
  • Low-power SERCOM and timer counters
  • Enhanced Peripheral Touch Controller (PTC) offers 4 μA standby with multi-button wake on touch and is highly responsive with superior water tolerance and excellent noise immunity

Technology and Innovation

  • eXtreme Low Power (XLP) and picoPower technologies
  • On-the-fly user-selectable performance levels
  • Automatic voltage regulator switching with multiple operating modes
  • Multiple power domains with automatic power domain gating
  • Automatic low-power SRAM switching with optional disable
  • Low-power battery backup mode

Large Portfolio and Efficient Performance Across Voltage Range

  • 14–128 pins
  • 8 KB–1 MB Flash
  • 25 MHz, 32 MHZ, 48 MHz, 96 MHz and 120 MHz performance levels
  • SAM and PIC32 family derivatives
  • 1.62V–3.6V operating voltage
  • Wide selection of packages
  • 1.93 × 2.43 mm WLCSP

The RE Family of 32-bit microcontrollers (MCUs) is based on the Silicon on Thin Buried Oxide (SOTB™) process technology, allowing it to realize both ultra-low current consumption in both active and standby mode and high-speed CPU operation (64MHz) at low voltage (1.62V), which is impossible to achieve with conventional bulk silicon processes. The RE01 MCU has been certified by EEMBC to have the highest score of 705 for the ULPMark-CP by the EEMBC ULPMark™ benchmark, which has been developed to provide a standard method to compare the energy efficiency of ultra-low power MCUs. In addition, the built-in energy harvesting control circuit enables the equipment to operate from energy harvesting power sources with only weak ambient energy.

The RE Family can significantly extend battery life and deliver high performance even for small batteries and energy harvesting power supplies that can supply only a small amount of current. The RE Family is suitable for many IoT applications such as hybrid watches, smart homes/buildings, healthcare, smart agriculture, structure monitoring, and trackers.

  • Operating Voltage: 1.62V to 3.6V
  • Operating temperature: -40°C to 85°C
  • External clock oscillators
  • • 8 to 32 MHz, 32.768 kHz
  • On-chip clock oscillators
  • • LOCO 32.768 kHz
  • • MOCO 2 MHz
  • • HOCO 24/32/48/64 MHz
  • Ultra-low power by SOTB
  • Energy Harvesting Controller (3μA
  • bootup)
  • Ultra-low power HMI (2DG + 8-bit MIP)
  • Ultra-low power ADC (at 4μA)
  • Crypto engine for security with Root of trust
Source: Renesas

RL78 8/16-bit microcontrollers (MCUs) greatly improve power efficiency with industry-leading low power consumption at 45.5μA/MHz consumption during normal operation and 0.57μA/MHz during clock operation. Built-in features such as a high-precision (±1%) high-speed on-chip oscillator, background operation data flash capable of 1 million rewrites, temperature sensor, and interface ports for multiple power supplies help reduce system costs and size.


Building on the successful Kinetis K Series (K22 and K24), the K32 L3 family of MCUs delivers a 50% improvement in power optimization and security advancements over the previous generation, to address a wide range of industrial and IoT applications. The K32 L3 MCU family is based on the power-efficient Arm® Cortex® -M4 core and offers a Cortex-M0+, providing new enhancements such as low-leakage power-optimized peripherals, a DC-DC converter, and security features like authenticated boot, secure update and tamper detection pins.

The introduction of the K32 L3 MCU family is the start of a long line of MCUs, which will further advance NXP’s security capabilities and power optimization features to lead the market in the next generation of low-leakage applications. The K32 L3 MCU family is complemented by a comprehensive ecosystem including MCUXpresso software and tools and a Freedom development board for easy prototyping.

Source: https://www.nxp.com/


  1. https://www.st.com/en/microcontrollers-microprocessors/stm32-ultra-low-power-mcus.html
  2. https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mcus/k32-l-series-cortex-m4-m0-plus:K32-L-Series
  3. https://www.microchip.com/en-us/solutions/low-power
  4. https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rl78-low-power-8-16-bit-mcus
  5. https://www.renesas.com/us/en/application/technologies/sotb
  6. Mouser electronics low power MCU application notes

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