Rev. 1.1 4/16

Copyright © 2016 by Silicon Laboratories

Si3402B-EVB

Si3402B-EVB

1. Description

The Si3402B non-isolated evaluation board (Si3402B-EVB Rev 2) is a reference design for a power supply in a

Power over Ethernet (PoE) Powered Device (PD) application. The Si3402B 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 Si3402B-ISO-EVB user’s guide.

2. Si3402B Board Interface

Ethernet data and power are applied to the board through the RJ45 connector (J1). The board itself has no

Ethernet data transmission functionality, but, as a convenience, the Ethernet transformer secondary is brought out

to the test points. Power may be applied in the following ways:

The Si3402B-EVB board schematics and layout are shown in Figures 1 through 6. The dc output is at connectors

J11(+) and J12(–).

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

output voltages by changing resistors R5 and R6. Refer to “AN956: Using the Si3402B PoE PD Controller in

Isolated and Non-Isolated Designs” for more information. The preconfigured Class 3 signature can also be

modified according to Table 3 in AN956. The D8–D15 Schottky type diode bridge bypass is recommended only for

higher power levels (Class 3 operation). For lower power levels, such as Class 1 and Class 2, the diodes can be

removed. When the Si3402B is used in external diode bridge configuration, it requires that at least one pair of the

CTx and SPx pins be connected to the PoE voltage input terminals (to the input of the external bridge).