Industrial and Instrumentation ICs
Volume 8, Issue 10 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

Protect Your Valuable Communication Networks with ADI's Family of RS-232 and RS-485 Digitally Isolated ICs

The RS-485 and RS-232 bus standards are the most widely used physical layer bus designs in industrial and instrumentation applications. To improve system reliability within a noisy environment and protect against voltage spikes and ground loops, isolation is required between the RS-485/RS-232 cable network and the systems connected to it. Power isolation is obtained through the use of an isolated dc-to-dc power supply or ADI isoPower integrated dc-to-dc converters. Signal isolation is implemented using iCoupler technology. ADI provides integrated isolated RS-485 and RS-232 transceivers to solve these problems.

The ADM3251E transceiver incorporates ADI's iCoupler and isoPower isolation technologies and is the first surface-mount RS-232 transceiver to feature full isolation of both the data lines and power. With a 2.5 kV isolation rating, the new RS-232 transceiver complies with industry-standard isolation regulations (UL1577 and DIN VDE 0884-10), ensuring it will meet the robustness levels required in noisy operating environments such as isolated RS-232 diagnostic data ports in industrial automation and control applications. The SMT package reduces board space by 45% compared with traditional ICs and helps to accelerate the manufacturing process and lower system development costs.

ADM3251E

ADM3251E Features

  • 2.5 kV fully isolated (power and data) RS-232 transceiver
  • 1 Tx and 1 Rx
  • Isolation: 2.5 kV
  • Integrated isolated dc-to-dc converter
  • Meets EIA-232E specifications
  • Charge pump capacitors: 0.1 µF
  • ESD protection on RIN and TOUT pins
  • Contact discharge: ±8 kV
  • Air gap discharge: ±15 kV
  • High common-mode transient immunity: >25 kV/µs
  • Data rate: 460 kbps
  • Safety and regulatory approvals
    • UL recognition
    • VDE certificate of conformity
  • Package: 20-lead W_SOIC

500 kbps/16 Mbps, Signal Isolated RS-485 Transceivers with Integrated Transformer Driver

The ADM2487E and ADM2482E meet the isolation requirements of RS-485 based physical layer industrial fieldbus networks, such as Modbus and BACnet. These products offer designers a higher level of integration than competing discrete solutions, resulting in a savings of board space and accelerated design time.

These devices employ ADI's iCoupler technology to combine a 3-channel isolator, a three-state differential line driver, and a differential input receiver into a single package. An on-chip oscillator outputs a pair of square waveforms that drive an external transformer to provide isolated power with an external transformer. Visit www.analog.com/rs485 and www.analog.com/rs232 for more information.

Please click here for the RS-485 Transceivers selection table.

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