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User's Guide

SLLU173B–October 2012–Revised June 2013

RS-485 Half-Duplex Evaluation Module

This manual describes the RS-485 Half-Duplex Evaluation Module (EVM). This EVM helps designers

evaluate the device performance, supporting the fast development and analysis of data transmission

systems using any of the TI RS-485 half-duplex devices in an 8-pin SOIC package.

Contents

1 Overview ..................................................................................................................... 2

2 EVM Setup and Precautions .............................................................................................. 3

3 Powering Up the EVM and Taking Measurements ..................................................................... 5

3.1 Measurement Examples .......................................................................................... 5

List of Figures

1 Typical Applications Diagram.............................................................................................. 2

2 RS-485 Half-Duplex EVM Schematic .................................................................................... 3

3 Bridging DUT_GND with EARTH_GND.................................................................................. 4

4 Example for Stimulus and Probe Points with JMP4 and JMP14 ..................................................... 4

5 Transceiver Configuration for Normal Operation ....................................................................... 5

6 RS-485 Half-Duplex EVM Setup for Normal Transceiver Operation................................................. 6

7 Configuration for Maximum Loading...................................................................................... 6

8 RS-485 Half-Duplex EVM Setup for Maximum Loading ............................................................... 7

9 RS-485 Half-Duplex EVM Configurations: Left as Receiver EVM, Right as Transmitter EVM ................... 7

10 Top View of RS-485 Half-Duplex EVM................................................................................... 8

11 Bottom View of RS-485 Half-Duplex EVM............................................................................... 8

SLLU173B–October 2012–Revised June 2013 RS-485 Half-Duplex Evaluation Module

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Summary of content (13 pages)

PAGE 1
User's Guide SLLU173B – October 2012 – Revised June 2013 RS-485 Half-Duplex Evaluation Module This manual describes the RS-485 Half-Duplex Evaluation Module (EVM). This EVM helps designers evaluate the device performance, supporting the fast development and analysis of data transmission systems using any of the TI RS-485 half-duplex devices in an 8-pin SOIC package. 1 2 3 Contents Overview ...................................................................................................................
PAGE 2
Overview 1 www.ti.com Overview TI RS-485 half-duplex devices in the 8-pin SOIC package have robust drivers and receivers in a small package for demanding industrial applications. The bus pins are robust to ESD events, with high levels of protection to Human-Body Model and IEC Contact Discharge specifications. These devices each combine a differential driver and a differential receiver, which operate from a single power supply.
PAGE 3
EVM Setup and Precautions www.ti.com 2 EVM Setup and Precautions Figure 2 shows the schematic of the EVM. The EVM board has headers labeled from JMP1 to JMP14 (JMP5 is omitted) and two 3-pin terminal blocks labeled TB1 and TB2. These headers support device evaluation for a wide range of system configurations. NOTE: The examples in this document show a 3.3-V signal generator and a 3.3-V power supply unit.
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EVM Setup and Precautions www.ti.com For the first measurements, ignore the common-mode simulation and connect EARTH to GND through a wire-bridge between pin 1 and pin 2 of TB1. PSU 3.3V 3 2 1 TB1 Figure 3. Bridging DUT_GND with EARTH_GND While JMP2 to JMP4 are stimulation points, or headers through which the control and data signals for the RS485 Half-Duplex EVM are applied, JMP1, and JMP11 to JMP14 are probe points, or headers at which these signal can be measured.
PAGE 5
Powering Up the EVM and Taking Measurements www.ti.com 3 Powering Up the EVM and Taking Measurements The generally recommended procedure for taking measurements is listed: 1. Install the required ground connections. 2. Connect the oscilloscope with the respective probe points you want to measure. 3. Adjust the power-supply to match the VCC requirements of the selected RS-485 device. 4.
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Powering Up the EVM and Taking Measurements www.ti.com Signal Generator Scope PSU1 3.3V Ch1 Ch2 Ch3 3.3V Ch4 TB1 VCC 3 1 2 3 4 VCC VCC DE R JMP3 2 1 2 3 4 JMP11 1 2 3 GND VCC /RE EARTH 1 2 3 4 1 JMP2 JMP6 1 2 3 4 B A JMP4 JMP14 1 2 3 D Figure 6. RS-485 Half-Duplex EVM Setup for Normal Transceiver Operation The low potential for RE is provided by the wire-bridge from pin 2 to pin 3 at JMP2, and the high potential for DE through a wire-bridge from pin 2 to pin 1 at JMP3.
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Powering Up the EVM and Taking Measurements www.ti.com • • • • replace R5 (120-Ω default) with 60 Ω replace R8 and R9 (0-Ω default) with 375 Ω connect pin 2 of JMP7 with pin 1 and pin 3 with pin 4 replace the previous wire-bridge at TB1 with a second power supply unit (PSU2) and connect the ground terminals of both, PSU1 and PSU2 with a wire-bridge, as shown in Figure 8. Signal Generator Scope PSU2 PSU1 VCM 3.3V Ch4 Ch3 Ch2 3.
PAGE 8
Powering Up the EVM and Taking Measurements www.ti.com Figure 10. Top View of RS-485 Half-Duplex EVM Figure 11. Bottom View of RS-485 Half-Duplex EVM For detailed information on the device parameters see the data sheet of the selected device at www.ti.
PAGE 9
EVALUATION BOARD/KIT/MODULE (EVM) ADDITIONAL TERMS Texas Instruments (TI) provides the enclosed Evaluation Board/Kit/Module (EVM) under the following conditions: The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user indemnifies TI from all claims arising from the handling or use of the goods.
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FCC Interference Statement for Class B EVM devices This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
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【Important Notice for Users of this Product in Japan】】 This development kit is NOT certified as Confirming to Technical Regulations of Radio Law of Japan If you use this product in Japan, you are required by Radio Law of Japan to follow the instructions below with respect to this product: 1. 2. 3. Use this product in a shielded room or any other test facility as defined in the notification #173 issued by Ministry of Internal Affairs and Communications on March 28, 2006, based on Sub-section 1.
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EVALUATION BOARD/KIT/MODULE (EVM) WARNINGS, RESTRICTIONS AND DISCLAIMERS For Feasibility Evaluation Only, in Laboratory/Development Environments. Unless otherwise indicated, this EVM is not a finished electrical equipment and not intended for consumer use.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.