Skyworks Solutions Inc. SI3404ISOC3-KIT

Overview

SI3404ISOC3-KIT from Skyworks Solutions is an evaluation kit for the Si3404 IEEE 802.3at Type 1-compliant Power over Ethernet (PoE) Powered Device (PD) controller IC. It integrates hotswap FET, current-mode DC-DC regulator, surge suppression, and IEEE detection/classification circuitry in a 4 × 4 mm QFN package. Designed for non-isolated and isolated flyback or buck topologies, it supports up to 12.95 W input power with tunable switching frequency (100–500 kHz) and operates across –40 °C to +85 °C.

For engineers reviewing the SI3404ISOC3-KIT datasheet, SI3404ISOC3-KIT pinout, SI3404ISOC3-KIT application, or SI3404ISOC3-KIT equivalent, this kit enables rapid validation of PoE PD designs targeting VoIP phones, IP cameras, wireless access points, and point-of-sale terminals - with full support for IEEE 802.3af/at Type 1 classification, auxiliary bias winding integration, and transformerless operation.

Technical Context

The SI3404ISOC3-KIT implements a complete PoE PD reference design centered on the Si3404 IC, featuring integrated hotswap switch (RON ≤ 2.9 Ω), current-mode PWM controller with 250 kHz fixed or resistor-tuned oscillator (100–500 kHz), and dual feedback paths (FBH for buck, FBL for non-isolated flyback, EROUT for isolated flyback). It validates IEEE 802.3at Type 1 compliance including 25 kΩ detection signature and Class 0–3 classification currents (0–30 mA).

Hardware includes external RDET (24.9 kΩ), RCLASS (48.7 Ω for Class 3), RFREQ (39 kΩ for ~470 kHz), ISNS sense resistor, and VT15 bias winding interface. The board supports both primary-side (VT15) and secondary-side (VDD) regulation, thermal shutdown at 160 °C, and output short protection with 1 ms detection threshold.

Key Specifications

Availability

SI3404ISOC3-KIT is available at Aetrix Electronics and suitable for PoE-powered voice telephony, surveillance camera deployment, enterprise wireless infrastructure, and industrial network device development requiring stable component supply and fast time-to-validation.

Supply support for SI3404ISOC3-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 Si3404 product line delivers fully integrated PoE PD interfaces targeting cost-sensitive, space-constrained endpoints needing robust IEEE 802.3af/at compliance without external controllers or discrete FETs.

FAQ

What is the SI3404ISOC3-KIT used for?

The SI3404ISOC3-KIT is an evaluation kit designed to validate and accelerate development of PoE-powered devices using the Si3404 PD controller IC. It demonstrates IEEE 802.3at Type 1 compliance, supports buck, non-isolated flyback, and isolated flyback topologies, and includes all necessary external components - such as RDET, RCLASS, RFREQ, and VT15 bias circuitry - to verify detection, classification, soft-start, thermal protection, and DC-DC regulation behavior of the SI3404ISOC3-KIT in real-world applications.

Does the SI3404ISOC3-KIT support IEEE 802.3bt (PoE++)?

No, the SI3404ISOC3-KIT is based on the Si3404 IC, which is explicitly specified for IEEE 802.3af and 802.3at Type 1 only. It does not support 802.3bt's higher power classes (Type 3/4), four-pair operation, or autoclassification. The SI3404ISOC3-KIT implements single-event classification and maximum 12.95 W input power - consistent with 802.3at Type 1 - and lacks hardware or firmware provisions for 802.3bt negotiation or multi-event classification sequences.

Can the SI3404ISOC3-KIT be used with an auxiliary transformer bias winding?

Yes, the SI3404ISOC3-KIT includes a dedicated VT15 input circuit that accepts 12–16.5 V from an auxiliary transformer bias winding. When enabled, this path powers the internal 11 V regulator, bypassing the less efficient internal coarse regulator and improving overall system efficiency by up to 3–5%. The board provides test points and routing to connect an external bias source, and the Si3404 datasheet confirms VT15 functionality is fully supported on the SI3404ISOC3-KIT.

What topologies are demonstrated on the SI3404ISOC3-KIT?

The SI3404ISOC3-KIT validates three DC-DC converter topologies: buck (using FBH feedback referenced to VPOS), non-isolated flyback (using FBL feedback referenced to VSS), and isolated flyback (using EROUT current-output error amplifier with optocoupler-based compensation). Each topology is implemented with populated components and documented in the kit's user guide, enabling direct comparison of efficiency, transient response, and layout trade-offs for the SI3404ISOC3-KIT.

Is the SI3404ISOC3-KIT RoHS-compliant and lead-free?

Yes, the SI3404ISOC3-KIT uses the Si3404-A-GM IC, which is explicitly listed in the Skyworks ordering guide as Pb-free and RoHS-compliant. The evaluation board itself follows IPC-7351 land pattern standards and uses RoHS-compliant PCB finish, solder mask, and passive components - confirmed in the Skyworks Si3404 Data Sheet Rev. 1.1 and packaging documentation for the SI3404ISOC3-KIT.