Silicon Labs ICs suit small IoT devices

  • March 22, 2023
  • Steve Rogerson

Texas-based Silicon Labs has announced two integrated circuit families for the smallest form factor IoT devices.

The xG27 family of Bluetooth systems on chips (SoCs) and the BB50 microcontroller unit (MCU) range in size from 2mm-squared, about the width of a #2 pencil lead, to 5mm-squared, less than the width of a standard #2 pencil.

They offer IoT device designers energy efficiency, performance, security and, in the case of the xG27, wireless connectivity. This makes them suitable for tiny, battery-optimised devices such as connected medical devices, wearables, asset monitoring tags, smart sensors, simple consumer electronics such as toothbrushes and toys, and more.

“Silicon Labs is the pure-play IoT leader, and our breadth, depth and focus enable us to support the broadest range of wireless connectivity protocols of any semiconductor company,” said Silicon Labs CEO Matt Johnson. “The xG27 SoCs and BB50 MCUs are helping developers build exciting new devices while also simplifying their development processes, all while maintaining the low-power and small form-factor requirements for extremely small devices.”

The xG27 family of SoCs comprises the BG27, for Bluetooth connectivity, and the MG27, supporting Zigbee and other proprietary protocols. Built around the Arm Cortex M33 processor, the BG27 and MG27 share several common features designed to make them suitable for small form-factor devices, including:

  • Wafer-level chip scale packaging as small as 2.3 by 2.6mm, suitable for compact and unobtrusive devices such as medical patches, continuous glucose monitors, wearable electrocardiograms and asset tags in various settings such as retail and agriculture.
  • Integrated DC-DC boost that can allow the devices to operate on batteries as low as 0.8V, thereby reducing their devices’ size, form factor, and cost.
  • Integrated coulomb counter that enables battery level monitoring to avoid battery depletion during the use of applications, improving user experience and product safety.
  • Security with Secure Vault with virtual security engine (VSE) for secure boot and debug hardened against glitch attacks, tamper protection and additional features to protect the device and its users’ data from local and remote cyber threats.
  • Shelf mode that reduces energy use to less than 20nA so devices can be transported and stocked on shelves while maintaining nearly full battery life for the end user.

Lura Health, a medical device manufacturer and participant in the alpha programme for BG27, has already selected the SoC to form the basis of its in-development smart wearable. But unlike some of the most common wearables on the wrist or other external skin, the Lura Health monitor goes in a person’s mouth. Specifically, the device is so small it is glued to a tooth. With the device, dentists and other clinicians can collect important data from saliva, which is used to test for over 1000 health conditions.

“The BG27 is amazing because it’s small enough that we can develop an IoT sensor smaller than a tooth, the power consumption is low enough to remove battery life as a product constraint, it has enough memory to store a sophisticated firmware application, it allows us to perform the data analysis required to gain insightful information from what we are monitoring, and it has all the peripherals we need to interface with our sensors,” said Noah Hill, CTO of Lura Health. “We spent hundreds of hours searching for a microcontroller that meets our needs, and the BG27 checks every box.”

While the IoT is built around connectivity, many devices do not need to be connected, and there are non-connected versions of connected devices.

For example, in commercial lighting, the application may need a simple control mechanism for the light based on ambient light or occupancy sensors. In the consumer goods space, many toothbrush manufacturers have recently built connectivity into their brushes, which provides users with friendly reminders and insights about their brushing patterns. However, some consumers still prefer non-connected versions of the device and simply want an electric toothbrush.

While, in theory, this seems like a simple problem to solve, it can often lead to inventory and SKU sprawl, with the non-connected version of a product being designed differently than the connected version. Add in different cosmetic effects such as colour or if the outer material is metal or plastic, and very quickly management of inventory and various designs becomes costly and complex.

Other devices such as LED lighting, keypads, drones, toys and anything with flashing lights or a motor still require a processor to control those essential functions, regardless of whether it is connected for added functionality.

The BB50 MCU and the larger BB5x MCU family help address these problems with common tools and software for 8 and 32bit, such as Silicon Labs Simplicity Studio and a fully-featured 8bit compiler.

The core is optimised for a large number of single-cycle instructions to improve operating efficiency. Wide operating voltages and low-power modes for battery applications improve energy efficiency for many battery sizes. Hundreds of firmware examples let users add functionality to an existing product with little or no additional firmware development effort.