In his Break Points column, Power management, 2011,” Jack Ganssle takes on the challenge of embedded MCU design for today's demanding application environments that require both high performance and low power, but at as low a cost and in as small a physical footprint as is possible.
Operating at lowest possible power is a given in most traditional 4-, 8- and 16-bit embedded applications. But the new generation of 32-bit power-hungry CPUs and their use in mobile and untethered wireless sensor designs has raised a number of new challenges.
In his column, Jack looks at the way companies such as Microchip, with its 8-, 16- and 32-bit PIC MCUs, and Texas Instruments, in its 16-bit MSP430s and high end 32-bit ARM-based OMAP designs, address these challenges.
Jack concludes with the observation that:
“The world of power management is far bigger than the simple sleep modes we use on our smaller controllers. It's great for consumers who get devices that will run for days on a charge. I wonder if these techniques will find their way into other consumer appliances, like TVs, in the days ahead, which promise perhaps significantly higher energy costs.”
Below are links to a range of How-To design articles, white papers, Webinars, and online tutorials to help you keep up with advances in power management in MCU designs. My Editor's Top Picks are:
For more detail on the low power design strategies used by TI and Microchip and how they compare you should also sign up for two sponsored white papers – one by Microchip and the other by TI – comparing their PIC XLP and MSP430 strategies, respectively. Good reading! (Embedded.com Editor Bernard Cole,, 928-525-9087)
Design How Tos
Choosing the right low power processor for your embedded design
Here are some suggestions about design criteria you need to consider when selecting a low power processor for your embedded system design needs
Use an MCU's low-power modes in foreground/background systems
The proper use of an embedded MCU's low-power/sleep modes is critical to a design's success.
Squeeze power efficiency out of processor-based designs — Part one
Processors play a key role in minimizing power consumption and extending battery life. Too often, designers limit their options for minimizing power consumption to little more than using low-power components. In fact, because processors can control the entire system, they in turn offer several ways to reduce and save on power consumption.
Software strategies simplify power puzzle
Battery-operated applications are not the only ones that demand low power.
Lower MCU power consumption by using omniscient code generation
Using omniscient code generation, compilers can have a significant effect on the number of instructions needed for apps on 8-/16-bit MCUs, significantly reducing power consumption.
How to manage dynamic power in a microcontroller using its non-maskable interrupt
This scheme allows MCUs to be made power-efficient and hence the durability of standby coin battery cells can be increased to match the product's life cycle.
Low power MCU selection criteria and sleep mode implementation
Discussed are key MCU low power features such as low power capabilities, flexible clocking systems, event-driven resources that affect its performance and provides selection criteria to choose the right one. Also explored are hardware/software techniques to achieve intelligent power management using low power modes.
Demystify power gating and stop leakage cold
Every designer of electronics feels the pressure to develop with an eye toward managing power. But leakage in nanometer geometries adds another level of complexity to these designs. What can be done? Here's a technique called power gating that addresses these challenges. Get the insight you need to demystify any apprehensions about its implementation.
Avoiding ultralow-power design pitfalls
Engineers today are tasked with developing cost-effective microcontroller-based ultralow-power embedded applications that are routinely required to operate for years on the same battery. In such applications, every microamp of current must be carefully scrutinized. The designer must understand just where power is consumed.
PRODUCT HOW-TO: Developing apps on an energy-friendly MCU designed for a 20-year battery life
The power management features of Energy Micro’s EFM32 MCU and how to use the development kit’s Advanced Energy Monitor feature to measure continuous current in the power rail feeding the MCU core and use an ADC to integrate the readings to give an accurate measurement of power over time.
Power aware verification of ARM-based designs
How to deal with the challenges of power aware verification in SoCs and use IEEE 1801-2009 Unified Power Format to define power management architecture for verifying a power-managed ARM-based design. (Paper from ARM TechCon 2010.)
Building a multi-voltage, high performance, ultra low standby power 32-bit MCU
In this “how we did it,” Jean-Michel Gril-Maffre describes what STMicroelectronics engineers did to enhance the performance of the ARM Cortex-M3 core in its STM 32 MCUs and simultaneously lower power consumption.
How microcontrollers add to battery life
How many battery-powered devices have you used since waking up today? Whether toothbrushes, shavers, cell phones, personal digital assistants, MP3 players and a remote control for anything not in arm's reach, battery-powered devices are an everyday part of life. As such, power management is an issue for designers choosing a microcontroller for these applications, so it's important to take a look at some enhanced features finding their way onto the latest microcontrollers (MCUs).
Analysis: TI focuses on low power with new chips
BDTI analyzes TI's low-power variants of its four key processor product lines: C55x, C64x+, C67x, and OMAP.
MCUs – 18-pin PIC MCUs feature Enhanced 8-bit Core, low power consumption
Microchip's 18-pin PIC MCUs feature Enhanced 8-bit Core, low power consumption, and provide higher speeds and lower cost than legacy PIC MCUs.
MCUs – Microchip unveils new low-power 8-bit PIC MCUs with nanoWatt XLP
Microchip has launched a new family of high-performance PIC18F/LF1XK22 MCUs that enable extremely low sleep currents. The new MCUs are available in 20-pin packages.
STMicroelectronics Unveils 26 Ultra-Low-Power, 8-bit MCUs
STMicroelectronics launches 26 8-bit MCUs with less than 400nA static power and 150μA/MHz dynamic power consumption
TI adds two new devices to industry's lowest power 16-bit DSP platform
Texas Instruments Incorporated has added two new devices to the industry's lowest power 16-bit digital signal processor (DSP) C5000 platform.
TI MSP430 MCU breaks 500 Nano amp barrier
Targeting battery powered applications, the MSP430F20xx microcontrollers from Texas Instruments Inc. now deliver 500 nanoamps in standby mode utilizing a very low-power oscillator technology. The oscillator allows the MCU to be totally self-clocked in an ultra-low power standby mode with self-wakeup capability using no external components
Atmel's Flash MCUs improve impedance matching, lower power up to 50 percent
Atmel Corporation has introduced the SAM3S series of Flash microcontrollers that includes 18 general-purpose Cortex-M3 based Flash microcontrollers designed to improve impedance matching, simplify PCB design and save 50 percent power at 1 MHz operation with a consumption of only 2.3 mW.
Atmel : 128 KB flash MCU suits low-power applications
Atmel has announced a 128 KB picoPower megaAVR microcontroller, targeting size-constrained, low-power applications.
News & Analysis
New material for semis said to beat silicon
A new semiconductor material called molybdenite is claimed to be 100,000 times lower power than silicon, plus will allow the fabrication of much smaller transistors, according to researchers at Switzerland's Ecole Polytechnique Federale de Lausanne.
Low-power arena heats up
Microchip' NanoWatt XLP EXtreme low-power technology solution takes aim at TI's MSP430.
TI, MIT team to design ultra-low voltage chip
A new version of a Texas Instruments low-power microcontroller that implements an experimental design technique conceived at the Massachusetts Institute of Technology promises another 10-fold cut in power consumption.