Power management for IoT devices

Power management is an often overlooked yet critical area for both consumer and industrial IoT devices. In a battery powered device, optimizing dynamic as well as static power is imperative; power optimization can be addressed in three ways:

  • Power management control
  • IP implemented for low power
  • Power aware software

Power management control should address the inclusion of voltage and frequency scaling. For this to be optimally implemented inside an IoT device, the system designer needs to identify known power states for each of the major functional blocks within the device. The table below provides an example of valid power states for multiple blocks within an SoC.

IoT defined power states

IP blocks for IoT should be designed to include power control wrappers for power and frequency scaling as shown below. Imagination already provides power control wrappers that will enable a functional IP block to be set to a valid power state within the device.

For IP to be implemented for low power, the system designer must first identify the power management objectives. In the case of an IoT device that is turned off for significantly longer time periods of time, leakage power will dominate the power consumption of the device. In the example of leakage power domination, process selection (i.e. choosing a process technology with low leakage) is an imperative. In addition, implementing the chip with high Vt values and using power gating where possible will further reduce leakage.

IoT - Power management architecture

If the device is turned on for the majority of time (e.g. sensor hubs), dynamic power will dominate. To reduce the dynamic power, voltage and frequency scaling should be implemented as a part of the power management function. In addition, choosing processes and memory IP that can operate over low voltages, such as operating in the 0.7v to 0.8v regime in a 40nm process, is highly desirable.

A useful scheme to reduce power for a CPU is close timing based on reduced values of supply voltage; this is commonly referred to as voltage scaling. For example, operating a MIPS M-class processor such as the M5150 CPU through voltage scaling at 0.95v will result in a power reduction of 23% (vs. the value when operating at the 1.08v minimum voltage).

However, a lot of the dynamic power savings would be lost if the wireless communications systems operate inefficiently. Bluetooth Smart (previously known as Bluetooth Low Energy) is positioned for very low power wireless communications, but the power reduction comes at the cost of reduced range point-to-point communications, and low data rates. For applications requiring higher data rates, Wi-Fi would be a suitable solution.

To address these requirements, Imagination has developed Ensigma Whisper, a low-power Wi-Fi offering that includes baseband processing. Energy-aware Wi-Fi is possible in Whisper by exploiting the low-power aspects within the 802.11 specification. For example, Whisper can operate 802.11n over a single 2.4GHz band radio at power consumption levels comparable to Bluetooth.

Power management is a significant issue for IoT devices that are mobile or are required to be powered by small batteries for extended periods of time. The IP used in such devices must be designed for low power and be easily integrated into SoC level power management schemes.

If you are interested the latest IoT-related news and updates from Imagination, make sure to follow us on Twitter (@ImaginationTech, @MIPSguru, @MIPSdev), LinkedIn, Facebook and Google+.

Please leave a comment below

Comment policy: We love comments and appreciate the time that readers spend to share ideas and give feedback. However, all comments are manually moderated and those deemed to be spam or solely promotional will be deleted. We respect your privacy and will not publish your personal details.

Search by Tag

Search for posts by tag.

Search by Author

Search for posts by one of our authors.

Featured posts
Popular posts

Blog Contact

If you have any enquiries regarding any of our blog posts, please contact:

United Kingdom

benny.har-even@imgtec.com
Tel: +44 (0)1923 260 511

Related blog articles

Connecting to CES 2019

Attending CES on an annual basis does enable one to make comparisons and get a sense of how technology and trends are progressing. Therefore, as well as meetings and discussions around our recent graphics and AI announcements we took the

AI in the UK: Year in Review

As a company focused heavily on enabling AI processing, it’s important to us that the country where we live is supporting efforts around AI technology development and policy. Indeed, the government, academic institutions, investors, and the entire ecosystem in the

CES 2019 banner

Get some facetime with Imagination at CES 2019

As the holiday season starts to fade to a distant memory the reality of CES is once again looming large our horizons, promising a new flurry of technology announcements to try and make sense of. As the saying goes, what

Lenovo 300e

PowerVR 2018 consumer tech round-up

Before we shut up shop for the year here at Imagination HQ, we thought we take a quick look at some of the end user products that Imagination tech found its way into in 2018. Our IP has appeared in

Stay up-to-date with Imagination

Sign up to receive the latest news and product updates from Imagination straight to your inbox.

  • This field is for validation purposes and should be left unchanged.