Skyworks Solutions Inc. SI3406FB5V2-KIT

Overview

SI3406FB5V2-KIT from Skyworks Solutions is an IEEE 802.3at-compliant isolated flyback evaluation board for Power over Ethernet (PoE) Powered Device (PD) applications, delivering 5 V / 1.05 A output with end-to-end efficiency up to 80.3% at 50 V input using the internal rectifier bridge and 82.0% with synchronous secondary rectification enabled.

For engineers reviewing the SI3406FB5V2-KIT datasheet, SI3406FB5V2-KIT pinout, SI3406FB5V2-KIT application, or SI3406FB5V2-KIT equivalent, this EVB provides validated reference design data-including BOM, schematics, thermal imaging, EMI compliance (EN55032 Class B), load transient response, soft-start behavior, and MPS generation-for rapid PoE PD prototyping and compliance validation.

Technical Context

The SI3406FB5V2-KIT implements a current-mode-controlled isolated flyback topology integrating the Si3406 IC, which combines IEEE 802.3at PD interface logic (detection, classification, hot-swap, TVS protection) with a dc/dc controller featuring dynamic soft-start, cycle-by-cycle current limit, thermal shutdown, and optional synchronous rectification drive.

Switching frequency is fixed at 150 kHz for 5 V output via R18 = 130 kΩ; the board supports both internal diode bridge and external Schottky/silicon bridge configurations, with selectable MPS (automatic or user-controlled via nSLEEP) and configurable current limiting via ISNS pin sensing.

Key Specifications

Availability

SI3406FB5V2-KIT is available at Aetrix Electronics and suitable for PoE-powered IP cameras, VoIP phones, wireless access points, and industrial IoT edge nodes requiring stable component supply, pre-validated EMI compliance, and IEEE 802.3at interoperability testing.

Supply support for SI3406FB5V2-KIT 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

Skyworks Solutions is a global semiconductor company specializing in analog and mixed-signal connectivity solutions for wireless, broadband, automotive, and industrial markets.

The Si3406 product line delivers highly integrated PoE PD controllers targeting compact, high-efficiency, standards-compliant powered devices-designed to reduce BOM count, simplify layout, and accelerate time-to-certification.

FAQ

What is the primary function of the SI3406FB5V2-KIT?

The SI3406FB5V2-KIT is an evaluation board for the Skyworks Si3406 PoE PD controller, configured specifically for 5 V / 1.05 A isolated flyback power conversion. It serves as a reference design to validate IEEE 802.3at compliance, measure end-to-end efficiency (80.3% typical), verify EMI performance, and prototype PoE-powered systems without developing custom hardware from scratch. The SI3406FB5V2-KIT integrates all necessary detection, classification, and power conversion circuitry per the standard.

Does the SI3406FB5V2-KIT support synchronous rectification?

Yes, the SI3406FB5V2-KIT supports optional secondary-side synchronous rectification. When enabled-by populating the NVTFS6H888NLTAG MOSFET and associated components-the board achieves up to 82.0% end-to-end efficiency at 50 V input, improving thermal performance and reducing secondary-side conduction losses. The Si3406 IC drives the synchronous FET via the SYNCL pin, and the modification is documented in Section 3.14 of the UG443 user guide.

How is the switching frequency set on the SI3406FB5V2-KIT?

The switching frequency on the SI3406FB5V2-KIT is set to 150 kHz for the 5 V configuration by installing a 130 kΩ resistor (R18) on the RFREQ pin of the Si3406 IC. This value is explicitly listed in Table "Parameter" on page 1 of the UG443 document. Frequency selection is voltage-dependent: 177 kHz for 3.3 V and 123 kHz for 12 V, each using different R18 values.

What EMI standards does the SI3406FB5V2-KIT meet?

The SI3406FB5V2-KIT meets EN55032 Class B limits for both conducted emissions (tested with average and peak detectors) and radiated emissions (tested in vertical and horizontal polarizations at 3 m distance). Measurement data confirms compliance across the full frequency range, including quasi-peak validation at critical frequencies. These results are presented in Figures 21 and 23 of the UG443 user guide.

Can the SI3406FB5V2-KIT be used with non-PoE power sources?

Yes, the SI3406FB5V2-KIT can be powered via laboratory DC supply using either Endspan (blue/white-blue & brown/white-brown pairs) or Midspan (green/white-green & orange/white-orange pairs) connections, as detailed in Figure 3 and Figure 4 of the UG443 user guide. This allows bench validation without a PoE switch or injector, while preserving full functionality including detection, classification, and power conversion behavior.