Overview
1
Overview
These devices 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.The driver differential outputs and the receiver
differential inputs are connected internally to form a bus port suitable for half-duplex (two-wire bus)
communication. These devices all feature a wide common-mode voltage range making the devices
suitable for multi-point applications over long cable runs. These devices are characterized for industrial
applications.
NOTE:
The EVM board comes without a transceiver device soldered on the board. The user can
order any TI half-duplex RS-485 transceiver and solder it down on the EVM. This provides
the flexibility to evaluate any 8-pin SOIC half-duplex transceivers. The EVM Tools Folder
contains links to devices that work with this EVM. See
http://www.ti.com/tool/rs485-hf-dplx-
for more information.
2
EVM Setup and Precautions
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. Depending on the RS-485 device chosen, the user may need to provide a 5-V signal
generator input and 5-V power supply.
•
Pin 1 (EARTH) is a second ground pin that allows applying an external voltage between GND and
EARTH to simulate common-mode voltage conditions.
•
Pin 2 (GND) is connected to the negative output or ground terminal of the PSU. This pin represents the
ground potential of the device-under-test and the entire EVM. It also connects to various jumpers on
the board.
•
Pin 3 (VCC) is connected to the positive output of a regulated power supply unit (PSU) as it represents
the positive supply voltage of the device-under-test and also connects to various jumpers on the board.
2
RS-485 Half-Duplex Evaluation Module
SLLU173A – October 2012 – Revised November 2012
Copyright © 2012, Texas Instruments Incorporated