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LT1791

Design Notes

• Download
  RS485 Transceivers Sustain В±60V Faults &mdash DN203
  PDF, 92 Kb, File published: Apr 2, 1999
  Extract from the document

  RS485 Transceivers Sustain ±60V Faults – Design Note 203
  Gary Maulding
  Introduction
  The LTВ®1785 and LT1791 RS485/RS422 transceivers
  with В±60V fault tolerance solve a real-world problem
  of п¬Ѓeld failures in typical RS485 interface circuits.
  Modems and other computer peripherals use point-topoint RS422 connections to support higher communication speeds with better noise immunity over greater
  distances than is possible with RS232 connections.
  Multipoint RS485 networks are used for LANs and
  industrial control networks. All of these applications are
  vulnerable to the unknown, sometimes hostile environment outside of the controlled, shielded environment
  of a typical electrical equipment chassis. Because the
  RS485 transceivers are directly in the line of п¬Ѓre, the
  transceiver chips are often socketed PDIP packages to
  allow easy п¬Ѓeld servicing of equipment. Field failures
  in standard transceiver circuits are caused by data-line
  voltages exceeding the absolute maximum ratings of
  the transceiver chips. Installation wiring faults, ground
  voltage faults and lightning-induced surge voltages are
  all common causes of overvoltage conditions.
  5mA 0mA 1mA/DIV –60V –5mA
  –60 0V
  VA, VB RE …

Articles

• Download
  LT1785 and LT1791: 60V, Fault-Tolerant RS485/RS422 Transceivers &mdash LT Journal
  PDF, 193 Kb, File published: Jun 1, 1999
  Extract from the document

  DESIGN FEATURES LT1785 and LT1791: 60V, Fault-Tolerant
  RS485/RS422 Transceivers
  by Gary Maulding Introduction
  The LT1785 and LT1791 RS485/
  RS422 transceivers with В±60V fault
  tolerance solve a real-world problem
  of field failures in RS485 interface
  circuits. RS485 and RS422 data networks are used in a wide variety of
  data-communications applications.
  Modems and other computer peripherals use point-to-point RS422
  connections to support higher communications speeds with better noise
  immunity over greater distances than
  is possible with RS232 connections.
  Multipoint RS485 networks are used
  for LANs and industrial-control networks. These applications are
  vulnerable to the unknown, sometimes hostile environment outside of
  the controlled, shielded environment
  of a typical electrical-equipment chassis. Data line voltages exceeding the
  absolute maximum ratings of the
  transceiver chips can cause field failures of conventional transceiver
  circuits. Installation wiring faults,
  ground voltage faults and lightninginduced surge voltages are all common
  causes of overvoltage conditions that …

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Manufacturer's Classification

• Interface > RS485/RS422 Transceivers | Extended Temperature (H & MP) Interface