| Parameter | Specification |
|---|---|
| Main SoC | Silicon Labs EFR32FG23 |
| Wireless Protocol | WM-BUS (EN13757-4/3) |
| Transmit Power | 20 dBm |
| Communication Distance | 2.5 km |
| Communication Interface | UART |
| Dimensions | 26 x 16 x 3 mm |
| Weight | 1.23 grams |
| RF Parameters | Parameter Value | Notes |
| Working frequency band | 868 MHz | Different working modes, working at different frequencies |
| Transmitting power | 20 dBm | Command adjustable |
| Receive sensitivity (GFSK) | -125 dBm | 2.4 kbps, GFSK signal, Δf = ± 1.2 kHz, BER < 0.1% |
| Measured distance | 2.5 km | Clear and open, antenna gain 3.5dBi, height 1.5 m, frequency 868.33MHz, airspeed 4.8kbps |
| Hardware Parameters | Parameter Value | Notes |
| IC full name | EFR32FG23A020F256GM40-B | Other models in the same series can be replaced, welcome to consult and customize |
| Core | ARM Cortex®-M33 | Main frequency 78MHz, high-performance 32-bit ARM processor, with DSP instructions and floating-point unit |
| FLASH | 256 KByte | Other models in the same series can be replaced, up to 512 KByte, welcome to consult and customize |
| RAM | 32 KByte | Other models in the same series can be replaced, up to 64 KByte, welcome to consult and customize |
| Crystal frequency | 39MHz/32.768KHz | The module is connected inside |
| Size | 16(L) * 16(W) * 3(H) mm | - |
| Antenna type | IPEX/Stamp Hole | Equivalent impedance is about 50Ω |
| Communication interface | UART | Support hardware flow control RTS, CTS pins |
| Packaging method | Patch Stamp Hole | Pin spacing 1.27mm |
| Weight | 1.23g | - |
| Electrical Parameters | Min. | Typ. | Max. | Unit | Remarks |
| Power supply voltage | 2 | 3.3 | 3.8 | V | ≥3.3V can guarantee output power, exceeding 3.8V may damage the module |
| Communication level | - | 3.3 | - | V | Using 5.0VTTL, it is recommended to add level conversion |
| Transmit current | 60 | 65 | 70 | mA | ≤70mA@3.3V/20dBm, instantaneous power consumption |
| Receive current | 5 | 5.5 | 6 | mA | ≤6mA@3.3V/20dBm/EM0 |
| Sleep current | - | 1.8 | 2 | μA | ≤2uA@3.3V/20dBm/EM2 |
| Operating temperature | -40 | - | 85 | ℃ | - |
| Operating humidity | 10 | - | 90 | % | - |
| Storage temperature | -50 | - | 150 | ℃ | - |


Practical Application Scenarios
1. Smart Utility Metering (AMI)
The E50-900NW20SX is built to be the communication heart of residential and commercial smart meters. By leveraging the embedded WM-BUS firmware, utility companies can achieve interoperability between gas, water, and heat meters, allowing data concentrators to automatically collect and upload consumption data without manual intervention.
2. Complex Urban Meter Reading
In dense urban environments where RF signals often struggle with multi-path interference and building shielding, this module’s EFR32FG23 architecture provides excellent link budget performance. It enables mobile meter reading equipment to capture accurate data from meters located in basements or utility shafts from the street level.
3. Integrated Heat Distribution Monitoring
The module supports the EN13757 standard, which is critical for heat distribution meters in multi-dwelling units. It ensures that data regarding energy consumption and flow temperature is transmitted reliably from individual units to a building's central management system, facilitating accurate billing and efficiency analysis.

FAQ Section
1. Does this module require external drivers for WM-BUS communication?
No, the module is factory-loaded with proprietary firmware based on the EN13757-4/3 European standards. You can interface directly with the module using standard UART commands, simplifying the development process for embedded engineers.
2. Is this module suitable for long-term battery-operated devices?
Yes, the EFR32FG23 SoC is specifically optimized for low-power IoT applications. The E50-900NW20SX module supports low-power sleep modes, making it an excellent choice for utility meters designed to run for several years on a single battery.
3. How does this compare to standard LoRa modules for metering?
While LoRa is excellent for long-range, low-data-rate applications, this module is specifically optimized for WM-BUS protocols. It offers a more direct compliance path for projects adhering to European utility metering standards, ensuring seamless integration with existing M-BUS data concentrators and infrastructure.








