Introducing the Ultra-Low Power IoT-Optimized FG23L Sub-GHz SoC

Silicon Labs is extending our family of sub-GHz SoCs to include the FG23L, bringing high-performance and a lean memory footprint to resource-constrained IoT applications. This “Lite” variant is designed to deliver the ideal balance of performance, cost, and efficiency for battery-powered sensor nodes, remote fobs, smart city sensors, building automation, asset trackers, and other devices where cost-effective, long-range functionality is required.

When we first introduced the FG23, it was the world’s first sub-GHz SoC to combine long-range RF, PSA Level 3 security, and energy efficiency. We also recognized a growing need for more cost-effective long-range IoT solutions, and the FG23L is our answer to helping developers find the right balance of cost, performance, and features for application-specific sub-GHz projects.

FG23L Sub-GHz SoCs are Application-Optimized for Ultra-Low Power, Long-Range IoT Applications

The FG23L sub-GHz SoC has been created specifically to address the growing need for low-power, long-range IoT and industrial applications that don’t necessarily rely on resource-intensive tasks. An SoC designed for these applications can avoid the large memory overhead of wireless protocol stacks or user interface code. For example, driving a display often requires hundreds of kilobytes or more of RAM for pixel data and additional Flash for fonts, icons, and graphics middleware, along with extra program logic to manage rendering and input. Without a display, the firmware can remain lean, running only the core control and communication functions, which greatly reduces both RAM and Flash requirements.

These devices are lean and well-targeted for proprietary applications, offering exactly the right features to build reliable, efficient products without extra cost or complexity.

FG23L Sub-GHz SoCs: Application and Price Optimized with Superior Performance

Powered by a dual-core architecture with a 78 MHz Cortex-M33, the FG23L sub-GHz SoC provides up to 50 percent more processing performance than anything else available. With best-in-class radio performance and a link budget of ~146 dB, these devices enable up to twice the range for reliable connectivity thanks to a +20 dBm transmit power. Built-in support for 23 GPIOs, a 16-bit ADC, and LESENSE low-power operation ensures seamless system integration.

Connectivity has become as much a part of our lives as any development of the 20th century. And with its widespread use, manufacturers are creating more specialized devices for point-to-point proprietary industrial automation applications. By covering the full range of license-free sub-GHz ISM bands (110–970 MHz), devices can comply with local frequency regulations, ensuring broad interoperability. The inclusion of multiple modulation schemes further enhances adaptability, allowing solutions to be optimized for range, power consumption, or data throughput depending on the use case. This combination of wide frequency support and modulation options enables unmatched versatility, making sub-GHz technology an ideal choice for diverse wireless applications—from smart meters and industrial monitoring to agricultural sensors and smart city infrastructure.

Purpose Built on the Legacy of Leading Sub-GHz SoC Technology

The FG23L is an extension of the FG23, the industry’s first sub-GHz wireless SoC, and provides developers with a simple migration path for applications that may require more memory or features in the future. Starting with the FG23 instead of building a sub-GHz solution from the ground up means we can take advantage of Silicon Labs' legacy of radio expertise to provide performance advantages over other available solutions. The low active current of 36 µA EM0 @ 78 MHz HFRCO is as much as 40% lower active power than the closest competitor, offering the same low power advantages as the full-featured FG23. Maintains a low 1.2 µA EM2 DeepSleep current (16 kB RAM retention and RTC running from LFRCO) which results into 10+ Y of battery life.