Rev. 1.0 1/15

Copyright © 2015 by Silicon Laboratories

Si3402-EVB

Si3402-EVB

1. Description

The Si3402 non-isolated evaluation board (Si3402-EVB Rev 1.41) is a reference design for a power supply in a

Power over Ethernet (PoE) Powered Device (PD) application. The Si3402 is described more completely in the data

sheet and application notes. This document describes the evaluation board. An evaluation board demonstrating

the isolated application is described in the Si3402ISO-EVB user’s guide.

2. Si3402 Board Interface

Ethernet data and power are applied to the board through the RJ-45 connector (J1). The board may be powered by

the following:



Connecting a dc source to 1, 2 and 3, 4 (either polarity)



Connecting a dc source to 4, 5 and 7, 8 (either polarity)



Using an 802.3af-compliant PSE such as Phihong PSA16U-480 (PoE)

The board itself has no Ethernet data transmission functionality, but, as a convenience, the Ethernet transformer

secondary is brought out to the test points. The dc output is at connectors J4(+) and J3(–).

Boards are generally shipped configured to produce +5 V but can be configured for +3.3 V or other output voltages

by changing resistors R5 and R6. Refer to “AN296: Using the Si3400/1/2 PoE PD Controllers in Isolated and

point provided is J6, which is the power loss (PLOSS) indicator.

3. Schematics

The Si3402-EVB board schematics and layers are shown in Figures 1 through 6. The Si3402-EVB is normally

populated for 5 V output, Class 3 signature, and without the diode bridge bypass recommended for higher power

levels. Use the ordering option Si3402-C4-EVB for 5 V output, Class 4 signature, and diode bridge bypass for

higher power levels.