Power Management Techniques in Embedded Systems
Embedded systems need to be energy efficient during operation to ensure long battery lifetime, reduce utility power consumption, and prevent excess heat generation.
Modern components give designers more freedom to control power consumption by entering various power-saving modes and implementing a broad power management strategy.
Processors in embedded systems can be big power consumers, but they can also play an active role in managing power consumption with unique algorithms.
The ICs in this image can have lower power sleep modes, where they do not consume power until they receive a wake/alarm signal
Anyone who deals with electronics, whether as a designer or in some other function, knows that electronic components generate lots of heat. They can also consume plenty of power during operation. In today’s world, with such an emphasis on energy efficiency, there is always a focus on reducing power consumption in any electronic system.
Embedded systems are prime targets for power consumption reduction and increased energy efficiency for multiple reasons. Some of these systems need to run on a battery and require lifetimes spanning years with particular form factor requirements. Other systems may draw power from the grid or a generator, but they should still not waste power in order to conserve total energy usage and prevent excess heat generation.
Some basic power management techniques in embedded systems can go a long way towards reducing heat generation, excess power consumption during system idle, and much more. Today’s components, highly efficient regulator designs, and advanced power management algorithms can be very helpful for ensuring a new embedded system will be energy efficient. If you’re planning a new embedded system design, pay attention to these tips to keep your system running at peak power efficiency.
Power Reduction Using Power Management Techniques in Embedded Systems
All embedded systems provide computing power for specific purposes, but they contain much more than a CPU. There are many areas of embedded systems that can be targeted for energy reduction using some power management strategies:
Processor: The processor is the first target for reducing power consumption. Many processing units have a range of onboard features targeting energy savings. Similarly, systems with multiple processing blocks can be throttled on and off so that they only consume power when needed.
Power regulation: Selecting a power regulation strategy is important for ensuring the system’s power supply is highly efficient while still being able to supply the required amount of power to various system blocks.
Peripherals: Just like processors, various peripheral units may consume power even if they are not being actively used.
Signaling protocol selection: Different signaling protocols and digital interfaces consume different amounts of power and require different amounts of current.
Wireless communications: Analog front-ends and wireless blocks in an embedded system are one area where power consumption can be greatly reduced.
Embedded firmware and software: These areas require expertise in developing efficient algorithms for carrying out processing instructions.
The table below shows some opportunities for power savings in each of the areas mentioned above. A few of these areas are more prominent in embedded systems development and they deserve more attention. These particular areas are discussed below.
Software and Firmware
Very simply, code execution strategies involve writing code so that the system completes required tasks while minimizing the number of logical operations. Implementation of a computational task using digital logic can increase the algorithmic complexity of the task, and firmware developers should consider the logic they use to implement their algorithms.
For systems like single-board computers, the operating system itself should be optimized to minimize the number of tasks running in the background. Linux kernels are the standard for embedded computers, as they can be customized with as much or as little peripheral application support as needed. By eliminating background processes and services, the processor will be performing fewer tasks while idling and will consume less power.
Component and Processor Selection
As can be seen from the above table, power consumption is heavily dependent on component selection in each of the above areas. In particular, many processor units (MCUs, FPGAs, MPUs, etc.) are specifically marketed as low-power components and may enable the following power management techniques in embedded systems:
Execute instructions with various signaling protocols, so the lowest power protocol can be selected if needed.
Enter a low-power hibernation mode or idle mode, where the core voltage and frequency are scaled back to save power.
Reduce the sampling rate of ADCs or other receivers, which will reduce total power consumption when interacting with analog sensors.
Dynamically switch on/off various peripherals.
Use peripherals that have a disable/enable setting that can be triggered through a standard low-speed digital protocol (I2C, SPI, GPIO, etc.).
The last point requires a power management strategy where power is distributed to different functional blocks, each with its own power regulator. This is shown in the block diagram below, which can be implemented with some sensing interface and low-speed digital interface.
Block diagram showing peripheral power management techniques in embedded systems
When you need to implement any power management techniques in embedded systems, use the best set of system design and analysis tools you can find. Cadence provides powerful software that automates many important tasks in systems analysis, including power integrity simulations and power management analysis through an integrated set of field solvers.
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