Silicon Labs SLWRB4257A

Overview

SLWRB4257A from Silicon Labs is a dual-band 2.4 GHz / 915 MHz Flex Gecko radio evaluation board built around the EFR32FG14P233F256GM48 Wireless SoC, delivering 19 dBm conducted output power in both bands, featuring an on-board inverted-F PCB antenna for 2.4 GHz and SMA connector for 915 MHz external antenna use, and supporting RF development for proprietary wireless protocols in industrial sensor networks and smart utility metering.

For engineers reviewing the SLWRB4257A datasheet, SLWRB4257A pinout, SLWRB4257A application, or SLWRB4257A equivalent, this page delivers verified RF performance data, connector mapping to EFR32FG14 GPIOs, conducted/radiated test results per FCC/ETSI, matching network BOM, and integration guidance with the Wireless Starter Kit Mainboard and Simplicity Studio tools.

Technical Context

The SLWRB4257A implements two independent RF paths: a sub-GHz path (915 MHz) routed through a discrete balun (BAL1), SMA connector, and optimized L-C matching network targeting 19 dBm; and a 2.4 GHz path using a four-element harmonic-filtering matching network feeding a printed inverted-F antenna with 50 Ω impedance across 2400–2483.5 MHz. Both paths share the same EFR32FG14P233F256GM48 SoC but use separate power amplifier supplies (3.3 V from mainboard for SUBGRF_OP/ON and PAVDD) and dedicated crystal oscillators (32.768 kHz LFXO and 38.4 MHz HFXO).

RFVDD is supplied at 1.8 V from the SoC's internal DC-DC converter, while PA biasing is externally sourced - enabling precise control of output power and spectral purity. Conducted testing uses UFL (2.4 GHz) or SMA (915 MHz) connectors with calibrated spectrum analyzers; radiated testing validates EIRP compliance using external whip (915 MHz) or on-board IFA (2.4 GHz) antennas under standardized chamber conditions.

Key Specifications

Availability

SLWRB4257A is available at Aetrix Electronics and suitable for wireless protocol development, RF reference design validation, and regulatory pre-compliance testing requiring stable component supply, traceable sourcing, and documented radiated/conducted performance data.

Supply support for SLWRB4257A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Silicon Labs is a fabless semiconductor company specializing in secure, energy-efficient wireless and mixed-signal ICs for IoT, industrial, and consumer applications.

The SLWRB4257A belongs to the Flex Gecko radio board family, designed to accelerate development of proprietary sub-GHz and 2.4 GHz wireless systems using EFR32FG14 SoCs - with emphasis on RF matching fidelity, regulatory test readiness, and starter kit interoperability.

FAQ

What is the primary function of the SLWRB4257A?

The SLWRB4257A is a reference and evaluation board for the EFR32FG14P233F256GM48 Wireless SoC, enabling rapid prototyping and RF performance validation of dual-band (2.4 GHz / 915 MHz) proprietary wireless applications. It provides fully characterized conducted and radiated output power, matching networks, and direct integration with the Wireless Starter Kit Mainboard and Simplicity Studio tools - making SLWRB4257A ideal for pre-compliance testing and hardware reference design.

Does the SLWRB4257A support both conducted and radiated RF measurements?

Yes, the SLWRB4257A supports both measurement types: conducted testing via UFL connector (2.4 GHz) and SMA connector (915 MHz), and radiated testing using its on-board inverted-F antenna (2.4 GHz) or external whip antenna (915 MHz). Measured conducted output is 19 dBm in both bands; radiated EIRP reaches 21.4 dBm (2.4 GHz) and 20.8 dBm (915 MHz), with full harmonic compliance data documented in Rev. 1.00 of the BRD4257A Reference Manual.

How is the SLWRB4257A powered and what voltage rails does it require?

The SLWRB4257A receives 3.3 V power from the Wireless Starter Kit Mainboard via its board-to-board connector. Internally, RFVDD is regulated to 1.8 V by the EFR32FG14's on-chip DC-DC converter, while the sub-GHz and 2.4 GHz power amplifiers (SUBGRF_OP/ON and PAVDD) are supplied with 3.3 V directly from the mainboard - ensuring optimal PA efficiency and linearity without requiring external LDOs or DC-DC stages on the SLWRB4257A itself.

What are the key RF components used in the SLWRB4257A matching networks?

The SLWRB4257A uses Murata passive components exclusively in its RF matching networks: sub-GHz path employs LQW15AN-series inductors (L3–L7) and GRM1555C1H-series capacitors (C3–C10); 2.4 GHz path uses LQP15MN-series inductors (L1, L2) and GRM1555C1H-series capacitors (C1, C2). All values are optimized for 19 dBm operation and documented in Tables 4.1 and 4.2 of the BRD4257A Reference Manual.

Can the SLWRB4257A be used for ETSI EN 300-328 compliance testing?

The SLWRB4257A's 2.4 GHz radiated fundamental output (21.4 dBm EIRP) exceeds the ETSI EN 300-328 limit of 20 dBm EIRP by 1.4 dB. However, the board serves as a validated platform to assess required power reduction - e.g., via firmware TX power scaling - while maintaining harmonic compliance (all harmonics < –46.7 dBm). Thus, SLWRB4257A supports pre-compliance characterization but requires final tuning for full ETSI certification.