Skyworks Solutions Inc. SI3402B-EVB

Overview

SI3402B-EVB from Skyworks Solutions is a non-isolated evaluation board for the Si3402B Power over Ethernet (PoE) Powered Device (PD) controller, configured as a Class 3 PD reference design delivering +5 V output at up to 7 W. It supports IEEE 802.3-2015-compliant PoE input via RJ45 (J1), features configurable output voltage (3.3 V/5 V/9 V/12 V), and includes on-board test points, thermal vias, and ESD protection capacitors (C10–C17) for system-level IEC 61000-4-2 >15 kV tolerance.

For engineers reviewing the SI3402B-EVB datasheet, SI3402B-EVB pinout, SI3402B-EVB application, or SI3402B-EVB equivalent, this board serves as a validated hardware reference for rapid prototyping of non-isolated PoE PD power supplies - particularly where fast time-to-test, layout guidance, and pre-verified Class 3 signature compliance are critical in industrial IoT, VoIP phones, and networked sensors.

Technical Context

The SI3402B-EVB implements a synchronous buck topology using the Si3402B QFN20 IC, with external Schottky diode bridge (D8–D15) bypassing internal bridges for >7 W operation. It accepts PoE power across either data pairs (pins 1/2 & 3/6) or spare pairs (pins 4/5 & 7/8) of an RJ45 interface, and delivers regulated DC output at J11 (+) and J12 (–).

Board-level design includes feedback loop compensation via R7 (47 kΩ) and C7 (1 nF), output voltage set by resistor divider R5/R6 (e.g., 3.24 kΩ/8.66 kΩ for 5 V), and thermal management via VNEG-connected backside copper plane with ≥1 inch² thermal vias (1.0–1.2 mm pitch, 0.3–0.33 mm diameter).

Key Specifications

Availability

SI3402B-EVB is available at Aetrix Electronics and suitable for PoE-powered IP cameras, VoIP desk phones, wireless access points, and industrial edge sensors requiring stable component supply, rapid validation of non-isolated PD designs, and pre-verified layout practices.

Supply support for SI3402B-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

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

The SI3402B-EVB belongs to Skyworks' Power over Ethernet evaluation platform family, designed to accelerate development of robust, standards-compliant PD power supplies - especially for cost-sensitive, space-constrained non-isolated applications in enterprise and industrial networks.

FAQ

What is the primary function of the SI3402B-EVB?

The SI3402B-EVB is a non-isolated evaluation board for the Si3402B PoE PD controller IC. It provides a complete, pre-validated hardware reference design enabling engineers to rapidly prototype and test Class 3 PoE-powered devices. The SI3402B-EVB delivers regulated DC output (default +5 V) from IEEE 802.3-2015-compliant PoE input, with full schematics, layout files, and BOM documentation supplied by Skyworks.

Can the SI3402B-EVB be used for isolated PoE PD designs?

No - the SI3402B-EVB is explicitly a non-isolated evaluation board. Skyworks provides a separate reference design, the SI3402B-ISO-EVB, for isolated topologies. Using the SI3402B-EVB for isolation would violate its PCB layout, grounding scheme, and safety clearance design. For isolated applications, engineers must use the SI3402B-ISO-EVB or develop a custom isolated design per AN956 guidelines.

How is output voltage adjusted on the SI3402B-EVB?

Output voltage on the SI3402B-EVB is set by the resistor divider formed by R5 and R6, which feeds the FB pin of the Si3402B IC. The default 5 V configuration uses R5 = 3.24 kΩ and R6 = 8.66 kΩ. To change output voltage (e.g., to 3.3 V or 12 V), both resistors must be replaced per Table 2 in the user guide - values are precisely selected to maintain loop stability and meet target regulation accuracy without recompensation in standard ESR configurations.

Does the SI3402B-EVB include ESD protection components?

Yes - the SI3402B-EVB includes eight 1 nF X7R ceramic capacitors (C10 through C17) placed near the RJ45 connector to provide system-level ESD protection compliant with IEC 61000-4-2 up to >15 kV. These capacitors are populated by default and are recommended for all designs requiring high ESD immunity, especially in harsh industrial or uncontrolled environments where cable handling may induce transient events.

What thermal design features does the SI3402B-EVB implement?

The SI3402B-EVB implements dedicated thermal management for the Si3402B's VNEG pin, connecting it directly to a large backside copper plane (≥1 inch²) via an array of thermal vias (1.0–1.2 mm pitch, 0.3–0.33 mm diameter). This design ensures efficient heat dissipation during sustained >5 W operation and aligns with Skyworks' layout recommendations in AN956 to prevent thermal shutdown and maintain long-term reliability.