Echelon LonWorks USB Network Interface Uživatelský manuál stáhnout pdf (Strana 20)

14 LONWORKS USB Network Interface User’s Guide

Alternate Power Line Coupling Circuit

This appendix describes how to design a power supply and coupling circuit for the

U20 interface. Before attempting to do so, you must carefully read and

understand Chapter 4, Coupling Circuits, of the PL 3120 / PL 3150 Power Line

Smart Transceiver Data Book.

You also need to understand the power requirements of the U20 interface, and

the circuitry provided in the U20 interface and wall-plug coupling circuit/power

supply. These topics are described in this appendix.

U20 USB Network Interface Power Requirements

The U20 interface draws power through both the USB Series “A” plug and the

barrel connector (marked PL-20). The interface draws 5V power (used to power

most of the internal interface circuits) from the Series “A” connector. The

transmit amplifier power supply draws power through the barrel connector, and

the barrel connector is also used for coupling power line communication signals

back onto the power line network.

The U20 interface will draw no more than 50mA through the 5V USB Series “A”

plug. Table A.1 summarizes the U20 interface’s power requirements drawn

through the barrel connector:

Table A.1 Power Requirements Through Barrel Connector

Parameter Min Typ Max Units Description

Voltage 10 14 18 Volts DC voltage required for the U20

interface transmit amplifier.

Current --- --- 250 Milliamps Peak transmit current require

during packet transmissions.

The barrel connector on the U20 interface is a 2.1mm DC power jack with the

following pin out:

POSITIVE TIP

(+)

NEGATIVE BARREL

(-)

Figure A.1 U20 USB Network Interface Barrel Connector Pin Out

Wall-Plug Power Supply and Coupling Circuit

As you begin designing your own power line coupling circuit, it is imperative that

you carefully study the coupling circuits inside the U20 interface, as well as the

circuitry inside the supplied wall-plug coupling circuit/power supply. You must

also carefully read and understand the Wall-Plug Coupler and Power Supply

section in Chapter 4 of the PL 3120/PL 3150 Power Line Smart Transceiver Data

Book.

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Echelon LonWorks USB Network Interface Uživatelský manuál Strana 20