Power Management Techniques for Low-Energy IoT Devices

Display portlet menu

Power Management Techniques for Low-Energy IoT Devices

Display portlet menu

Power Management Techniques for Low-Energy IoT Devices

chart depicting device power states

With the rise of the Internet of Things (IoT), embedded designers are, more than ever, focusing their attention and efforts on system energy usage. A prime example is a wireless sensor node—a relatively simple device from a functional point of view that is required to do its job for an extended period (in some cases, years) while powered by a battery.

Design considerations include major system elements such as the microcontroller (MCU), wireless interface, sensor and system power management.

 

Figure 1 shows a typical wireless sensor node.
Figure 1: Typical Wireless Sensor Node Architecture

The MCU will need to be extremely energy efficient. Computational requirements will likely dictate the selection of a 32-bit or 8-bit MCU, yet low energy requirements remain regardless of the MCU choice. Energy consumption in low-power and active modes, as well as the need to quickly wake up from low-power modes to full-speed operation, will make a significant difference in conserving battery power.

Consider how much the chosen MCU can do without actually leveraging the CPU core itself. For example, significant power savings can be achieved through autonomous handling of sensor interfaces and other peripheral functions. Being able to generate the stimulus signal, or power supply, for the sensor from the MCU and read back and interpret the results without waking the MCU until “useful” data is obtained can go a long way toward maximizing the system’s battery life.

Let’s consider the wireless connectivity. The network topology (Figure 2) and the choice of protocols will both have an impact on the power budget required to maintain the wireless link. In some cases, a simple point-to-point link using a proprietary sub-GHz protocol may seem like an appropriate choice to yield the lowest demand on power from the battery. However, this configuration can limit the scope of where and how the sensor can be deployed.

“Design considerations include major system elements such as the microcontroller (MCU), wireless interface, sensor and system power management.”

A star configuration built on either 2.4 GHz or sub-GHz technologies increases the flexibility for multiple sensor deployment, but this would likely increase the complexity of the protocol, therefore increasing the amount of RF traffic and system power.

A third option to consider is a mesh configuration based on a protocol such as ZigBee. While a mesh network imposes the biggest drain on the sensor node battery, it also provides the greatest level of flexibility. Depending upon the wireless stack, a mesh network can also provide the most reliable deployment option with a self-healing network.

network topology exaples chart
Network Topology Examples

In a sensor node, the amount of data to be sent over the wireless link should be relatively small. As such, ZigBee provides an optimal mesh networking solution; Bluetooth Smart is an excellent choice for standards-based, power-sensitive point-to-point configurations, and proprietary sub-GHz solutions provide maximum flexibility for network size, bandwidth and data payloads in star or point-to-point configurations. Table 1 summarizes many of the key features and benefits of leading RF technologies used in IoT applications

primary differences between RF Protocols chart
Table 1: Primary Differences between RF Protocols

For very wide areas, long-range technologies and platforms such as LoRa and Sigfox, enable high node-count networks reaching up to tens of kilometers and with low-power systems. Data security is becoming more important. If the MCU used to run the stack does not have encryption hardware, it will have to burn multiple cycles to run the algorithm in software impacting the overall power consumption.

Numerous sensor choices are available and can range from discrete to fully integrated solutions. Discrete solutions may be power efficient, but place additional processing requirements on the MCU.

Building signal conditioning into the sensor provides some significant advantages. The data that is sent to the MCU will be relevant data that can be quickly and easily interpreted by the application, which means the MCU can stay asleep as long as possible. Having preconditioned data sent over a digital interface, such as SPI or I2C, also means the MCU can gather the data more efficiently than if it were using its ADC.

“If the MCU used to run the stack does not have encryption hardware, it will have to burn multiple cycles to run the algorithm in software impacting the overall power consumption.”

A final design consideration for low-energy applications is powering the system itself. Depending upon the type of battery used in the application, there is often a requirement for boost converters or boost-switching regulators. A careful choice can have a big impact on the system’s overall power consumption as solutions range from 1 uA – 7 uA consumption.

For more complex systems, a power management integrated circuit (PMIC) gives more precise control over the whole system. From a single power source, you can generate multiple voltage rails to drive different elements of the embedded system, tuning each voltage rail to provide just enough power for the application. A PMIC may also offer additional functionality for general system control, such as watchdog timers and reset capability.

Ultimately, there are many different system design aspects involved in designing low-energy, battery-powered applications. In addition to low-power semiconductor components, the approach to software, including wireless stacks, encryption and data processing, are important considerations. Each of these design elements can have a significant effect on the system’s overall power budget, while enabling developers to create low-energy IoT devices that maximize useful battery life.

Helpful Links

Power Management Techniques for Low-Energy IoT Devices

Display portlet menu

Power Management Techniques for Low-Energy IoT Devices

Display portlet menu
Related Articles
2D image of smart phone charging on mobile battery
Why does Iq matter for USB Type-C?
November 11, 2019
This change is driving an increase in demand for Type-C AC/DC chargers and power banks because the Type-C connector has flip capability which gives convenience to users.
avnet branded USB type C connector
It is time to say goodbye to Micro USB!
November 11, 2019
Type-C’s greatest advantage is its integration capability. In addition to not having a right or wrong side (a perennial problem for Micro USB users), Type-C is able to offer integrated power delivery (PD) during charging.
Using Programmable Logic to Build Power-Efficient Systems
October 29, 2019
The successful implementation of the Internet of Things (IoT) requires new thinking about how to power connected devices.
Woman jogger wearing a bluetooth running tracker
6 reasons why startups choose Bluetooth for their projects
July 26, 2018
Bluetooth technology originated in the 1990s, but its primary function was device-to-device (or point-to-point) protocol for securely sharing data between devices in close proximity. Think less music streaming, more wireless printers.
Battery powering
Batteries are key to charging options
July 6, 2018
Wired power is a strong option for developers that need to get to market fast and require an inexpensive, proven solution. For products where convenience and future compatibility are paramount, you can move forward confidently with standards-based wi
smart devices on charge pad: phone, watch and tablet
With the rising popularity of 7.5W wireless charging, Avnet helps companies obtain rapid product certification
February 25, 2018
The current wave of wireless charging technology, fueled by the new iPhone from Apple, is showing strong momentum growth. Semiconductor suppliers around the world have started making substantial investments in new IC solutions while a low barrier to
Person checking battery charge level on their cell phone
3 levels of Qi testing
November 24, 2017
You’ve designed, prototyped and built a revolutionary product with cutting edge Qi technology – congrats! Before you get to officially certifying your Qi product, you’ll need to do some testing to ensure its veracity.
man pulling smartphone from pocket
Watch for these two problems in your Qi wireless charging project
November 14, 2017
Here are two of the most common problems engineers face in integrating Qi wireless charging in their projects.
charging cell phone in automobile
How to get your Qi project certified by the Wireless Power Consortium
November 14, 2017
By aligning with the Wireless Power Consortium and Qi standard—the way big name brands like Apple, Samsung and Avnet have—you can help verify the quality of your product to new customers.
Bill Amelio, Avnet CEO
Qi standard is for more than just smartphones
By Bill Amelio   -   November 14, 2017
I’m not alone in my suspicion that the engineering world will soon follow a singular standard for wireless charging: the Qi standard. I think it would be the right move—and its impact would extend far beyond the charging of mobile phones.
side view of a sports car from the ground up
Understanding the Power of Battery Management Systems
August 28, 2017
According to estimates, China's EV battery market will reach RMB 120 billion by 2010, at which time the EV BMS market is expected to be valued at RMB 17 billion. Although the cost of BMS relative to the entire EV is relatively low, developers should
smart car driving towards a sunset
How far exactly can an Electric Vehicle (EV) travel?
August 20, 2017
"How far can an EV travel" is no longer just a question of mileage range technology but also one of great concern to businesses within the field, or rather how much more the industry can achieve. From the technical perspective, two problems must be r
man drawing schetch of an electric car attached to a battery
Technologies and Components for Designing Electric Vehicles
April 29, 2017
Hybrid electric vehicles (HEVs) such as the Toyota Prius and the Chevy Volt and electric vehicles (EVs) such as the Nissan Leaf, BMW i3 and Tesla Model S are growing in popularity amid concern for global warming.
energy harvesting concept with green batteries sprouting from the ground
Powering the Internet of Things via Energy Harvesting
April 25, 2017
The push is on to add Internet capability to everything—often called the Internet of Things (IoT)—and the challenge for design engineers is to figure out how to power each of these IoT nodes.
nurse checking person wearing health monitoring system on wrist
Internet of Things: Designing Sensor-Based Devices with Coin Cell Batteries
March 13, 2017
A popular vision of the Internet of Things (IoT) is that it will comprise billions of sensors gathering information about their local environment and transmitting that data back to servers in the cloud. Such data will be compiled, analyzed and shared

Power Management Techniques for Low-Energy IoT Devices

Display portlet menu
Related Events

No related Events found