Silicon Labs recently announced the BG22E, MG22E, and FG22E SoCs to support battery-free, energy-harvesting applications.
Silicon Labs chose Earth Day (April 22) to release its “most energy-efficient SoCs to date.” Image (modified) used courtesy of Silicon Labs
The company claims the family can optimize energy consumption, prolong device lifespan, and wake up at microsecond speeds, making it suited for small, low-complexity use cases. IoT devices can leverage Silicon Labs’ new family to support low-power modes or even go battery-free while harvesting energy from external sources in their environments, including indoor or outdoor ambient light, ambient radio waves, and kinetic motion.
E for Energy Conservation
Silicon Labs designed the xG22E family of SoCs for energy-harvesting solutions in agriculture, asset tracking, home and factory automation, and predictive maintenance. The three devices in the series—BG22E, MG22E, and FG22E—join Silicon Labs’ Wireless Gecko Series 2 platform.
The new E suffix at the end of the device part numbers denotes energy conservation capabilities aimed at extending battery longevity and, in some applications, eliminating batteries completely. The BG22E is a Series 2 Bluetooth Low Energy (Bluetooth 5) SoC, while the MG22E and FG22E use Zigbee and a proprietary 2.4-Ghz wireless protocol, respectively.
Three xG22E Iterations for Various Energy-Harvesting IoT Needs
All three SoCs operate on the 2.4 GHz radio frequency and feature 512 KB of Flash memory with 32 KB of RAM. The BG22E and MG22E feature a high-performance, 32-bit, 76.8 MHz Arm Cortex-M33 with DSP instruction sets, while the FG22E uses the same processor clocked slower at 38.4 MHz.
High-level block diagram of an xG22E device. Image used courtesy of Silicon Labs
Both the BG22E (datasheet linked) and BG22 feature several energy-conserving features, such as EM2 deep-sleep mode and a low-energy timer (LETIMER), which can be output from the device even when most of it is powered down.
In contrast to the BG22E, the MG22E uses Zigbee, making it suitable for low-power applications or applications that require a larger transmission distance. The MG22 and MG22E devices also offer secure boot with RTSL. Secure boot with RTSL uses a multi-stage process to verify the authenticity of the bootloader and application code so malicious bootloader code cannot take control of the chip at startup.
The xG22E Supports Lightning-Fast Wake-Up
What sets the BG22E (and other xG22E devices) apart from the BG22 (released in 2021) is its fast cold-start bootup and wake-up out of shut-off states (EM4). The xG22E device can wake up in only 8 milliseconds using a miniscule 150 micro-joules.
Internal diagram of the BG22E. Image used courtesy of Silicon Labs
In IoT applications, rapid, energy-efficient bootup is critical so devices can quickly respond to asynchronous events without spending too much time in a non-useful state. Silicon Labs also says that the xG2EE’s swift wake up from deep sleep reduces wake-up energy by 78% compared to other devices sold by the company.
Silicon Labs Joins Forces With Energy-Harvesting Specialist E-peas
In the same announcement for the xG22E family, Silicon Labs discussed a partnership with E-peas, a leading manufacturer of PMICs for energy harvesting. Energy-harvesting power management integrated circuits (PMICs) collect energy from ambient sources and convert it to electrical energy with very low losses.
E-peas’ AEM13920 harvests multiple energy sources as input. Image used courtesy of E-peas
Silicon Labs is offering a xG22E Explorer Kit in partnership with E-peas to help designers develop a complete energy-harvesting solution. The Explorer Kit includes two custom-fit, energy-harvesting shields tuned for different energy sources and energy-storage technologies. One of the energy-harvesting shields uses the E-peas’ AEM13920 PMIC, which can handle simultaneous inputs from two harvested energy sources. In other words, a complete energy-harvesting solution using the xG22E Explorer Kit could harvest from multiple sources of ambient energy, such as kinetic and heat energy. The second shield, based on E-peas’ AEM00300 shield, can harvest energy from random pulsed energy sources.
All About Circuits editor-in-chief Jeff Child meets with E-peas CEO and co-founder Geoffroy Gosset at Embedded World 2024.
These shields work together in the Explorer Kit to help users customize peripherals and debugging options and derive accurate measures for complete energy-harvesting solutions. Such solutions may include electronic shelf labels, solar-powered remote controls, wireless light and appliance switches, and beyond.
