Silicon Labs BG2B Sleeps at 1.1uA on Bluetooth 6

The Battery Math Behind a Microamp

Silicon Labs has introduced the BG2B, which the company describes as the lowest-power Bluetooth LE device in its portfolio. The headline figure is 1.1 microamps of EM2 deep sleep current with 16KB of RAM retained, alongside a 14-15% reduction in active MCU current against its predecessors. CNX Software covered the announcement on August 4, 2026.

• 1.1uA EM2 DeepSleep current with 16KB RAM retention, plus 14-15% lower active MCU current than previous parts
• Arm Cortex-M33 at 80MHz with DSP and floating-point unit, 64KB or 128KB SRAM, and 1016KB of flash
• Bluetooth LE 6 with Channel Sounding — Mode 3, NADM, and Inline PCT — plus a 2.4GHz proprietary mode
• Secure Vault High with hardware crypto acceleration, TrustZone, and PSA Level 3 certification readiness

Why Sleep Current Is the Only Number That Matters

For a device that transmits a short advertisement every few seconds and does nothing else, the energy budget is dominated almost entirely by the time spent asleep. A radio burst is measured in milliamps but lasts milliseconds; sleep is measured in microamps but lasts essentially forever.

The arithmetic is unforgiving. A CR2032 coin cell holds roughly 220mAh. At 1.1uA of continuous draw and nothing else, that is a theoretical ceiling in the range of twenty years — well past the cell's own shelf life. Real devices never approach that, because advertising, sensor sampling, and connection events all add up, but the sleep floor sets the ceiling on everything above it. Shaving a microamp off deep sleep can be worth more in shipped battery life than any amount of optimisation in the active path.

The 16KB RAM retention detail matters too. Retaining state means the device resumes rather than reboots, which avoids re-running initialisation and re-establishing security context — itself an energy cost that gets overlooked when comparing datasheet numbers.

What Is Channel Sounding For?

Bluetooth Channel Sounding is the ranging feature added in recent specification revisions, and the BG2B supports Mode 3 with NADM and Inline PCT. In plain terms, it lets two Bluetooth devices measure the distance between them accurately by timing signal phase, rather than guessing from received signal strength.

That distinction has real consequences. Signal-strength-based proximity is famously unreliable and famously spoofable — a relay attack simply amplifies the signal to make a key fob appear close. Phase-based ranging with NADM, which stands for Normalised Attack Detector Metric, is specifically designed to resist that class of attack.

The applications follow directly: keyless entry, asset tracking with real distance rather than "somewhere in this warehouse," and tools that need to know whether the operator is actually standing next to them.

The Rest of the Silicon

Sensitivity runs from -106.8dBm at 125kbps GFSK to -99.0dBm at 1Mbps, with transmit power up to +8dBm. Peripherals include up to 32 GPIO, CAN-FD, two 12-bit ADCs at 1Msps, four LED sinks with PWM control, and the usual complement of UART, SPI, and I2C.

CAN-FD on a Bluetooth part is an unusual inclusion, and Silicon Labs lists vehicle diagnostics among the target applications — alongside secure ranging, asset tracking, electronic shelf labels, smart home devices, and industrial monitoring.

Security is Secure Vault High: hardware cryptographic acceleration, Arm TrustZone, and readiness for PSA Level 3 certification. For anyone shipping into the EU, that certification path is becoming less optional every year as radio equipment cybersecurity requirements phase in.

Availability, and the Catch

The BG2B is currently available through early customer engagement, with official launch planned for 2027. That is a long runway, and it means this is a part to design in rather than to buy this week.

For makers who want ultra-low-power wireless today, the alternatives are the ones we have already covered — the nRF54L15 Discovery board is shipping now, and our low-power wireless MCU guide compares the current field. The BG2B is worth tracking for the sleep floor and for Channel Sounding, but it belongs on a 2027 roadmap rather than a 2026 bill of materials. Readers following mini computer and embedded hardware will want to watch what the announcement does to competitors' sleep-current claims over the next few months — that is usually where a number like 1.1uA has its fastest effect.

Sources: CNX Software — August 4, 2026; Silicon Labs wireless SoCs — 2026; Bluetooth SIG on Channel Sounding — 2026.