Skyworks Solutions Inc. SI3402-EVB

Overview

SI3402-EVB from Silicon Laboratories is a non-isolated evaluation board for the Si3402B Power over Ethernet (PoE) Powered Device (PD) controller IC, supporting IEEE 802.3-2015-compliant Class 3 operation with configurable 3.3 V, 5 V, 9 V, or 12 V DC output. It accepts power via RJ45 Ethernet interface (pins 1–2/3–6 or 4–5/7–8) and delivers regulated output at J11 (+) and J12 (–). Designed for PoE PD reference implementation in industrial and embedded networking equipment.

For engineers reviewing the SI3402-EVB datasheet, SI3402-EVB pinout, SI3402-EVB application, or SI3402-EVB equivalent, this page provides verified board-level specifications, supported PoE input configurations, output voltage setup options, thermal and ESD layout guidance, and integration notes for non-isolated PD designs using the Si3402B controller.

Technical Context

The SI3402-EVB implements a non-isolated flyback-derived topology using the Si3402B QFN20 PD controller, which integrates detection, classification, under-voltage lockout, hot-swap FET control, and DC-DC regulation feedback. It supports dual-pair or single-pair PoE power injection and enables external Schottky diode bridge bypass for >7 W applications.

Board-level design includes pre-configured Class 3 signature (R3 = 48.7 Ω), adjustable output voltage via R5/R6 resistor divider (e.g., 5 V with R5 = 3.24 kΩ, R6 = 8.66 kΩ), and ESD protection capacitors (C10–C17, 1 nF X7R, 100 V) for IEC 61000-4-2 >15 kV system-level immunity.

Key Specifications

Availability

SI3402-EVB is available at Aetrix Electronics and suitable for PoE-powered surveillance cameras, VoIP phones, wireless access points, and industrial IoT edge nodes requiring stable component supply and rapid prototyping of non-isolated PD implementations.

Supply support for SI3402-EVB 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 Laboratories Inc. is a U.S.-based semiconductor company specializing in mixed-signal ICs for timing, MCU, wireless, and power management applications, with emphasis on energy efficiency and system integration.

The SI3402-EVB belongs to Silicon Labs' Power over Ethernet evaluation platform family, designed specifically to accelerate development of IEEE-compliant Powered Devices using their Si3402B PD controller in non-isolated topologies.

FAQ

What is the primary function of the SI3402-EVB?

The SI3402-EVB is a non-isolated evaluation board for the Si3402B PoE PD controller IC. It demonstrates full IEEE 802.3-2015-compliant Powered Device functionality-including detection, classification, and regulated DC output-without galvanic isolation. The SI3402-EVB enables rapid validation of Si3402B-based designs in applications such as IP cameras and VoIP endpoints where cost and board space are constrained.

Can the SI3402-EVB be used with an isolated PoE architecture?

No-the SI3402-EVB is explicitly designated as a *non-isolated* evaluation board. For isolated implementations, Silicon Labs provides the separate Si3402B-ISO-EVB. The SI3402-EVB lacks transformer-based isolation and routes PoE input directly to the Si3402B's CTx/SPx pins and internal switcher; using it in place of an isolated design violates safety and regulatory requirements for mains-referenced systems.

How do I configure the SI3402-EVB for 3.3 V output?

To configure the SI3402-EVB for 3.3 V output, replace R5 with 3.24 kΩ and R6 with 4.64 kΩ (per Table in Section 4 of the user's guide), and use a 1000 µF/6.3 V standard-ESR capacitor (e.g., Panasonic ECA0JM102) for C5. Retain R7 = 47 kΩ and C7 = 1 nF for loop compensation. Confirm operation with load ≥250 mW to prevent pulsing and false disconnect.

Does the SI3402-EVB support both data-pair and spare-pair power injection?

Yes-the SI3402-EVB accepts PoE power on either configuration: data pairs (pins 1,2 and 3,6 of the RJ45) or spare pairs (pins 4,5 and 7,8), with polarity-insensitive input. This flexibility allows compatibility with both endspan (switch-integrated) and midspan (injector-based) PSEs, including models like the Trendnet TPE-1020WS referenced in the SI3402-EVB documentation.

What is the role of the D8–D15 diode bridge on the SI3402-EVB?

The D8–D15 Schottky diode bridge (SS2150) on the SI3402-EVB provides external bypass of the Si3402B's internal diode bridges for >7 W operation, improving thermal performance and efficiency. It is recommended only for Class 3 applications; for Class 1/2 (<3.84 W), these diodes may be omitted to reduce BOM cost and board area without affecting functionality of the SI3402-EVB.