ADM2485:  High Speed, Isolated RS-485 Transceiver with Integrated Transformer Driver

The ADM2485 differential bus transceiver is an integrated, galvanically isolated component designed for bidirectional data communication on multipoint bus transmission lines. It is designed for ...More

ADM2485:  High Speed, Isolated RS-485 Transceiver with Integrated Transformer Driver

Product Description

The ADM2485 differential bus transceiver is an integrated, galvanically isolated component designed for bidirectional data communication on multipoint bus transmission lines. It is designed for balanced transmission lines and complies with ANSI/TIA/EIA RS-485-A-98 and ISO 8482:1987(E).

The device employs Analog Devices, Inc., 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. The logic side of the device can be powered with either a 5 V or a 3.3 V supply, and the bus side is powered with an isolated 5 V supply.

The ADM2485 driver has an active high enable. The driver differential outputs and the receiver differential inputs are connected internally to form a differential input/output port that imposes minimal loading on the bus when the driver is disabled or when VDD1 or VDD2 = 0 V. Also provided is an active high receiver disable that causes the receive output to enter a high impedance state.

The device has current-limiting and thermal shutdown features to protect against output short circuits and situations where bus contention might cause excessive power dissipation. The part is fully specified over the industrial temperature range and is available in a 16-lead, wide-body SOIC package.

Applications

  • Isolated RS-485/RS-422 interfaces
  • PROFIBUS networks
  • Industrial field networks
  • Multipoint data transmission systems

    • Data Sheet, Rev. A, 12/07

    Features

    • Half-duplex, isolated RS-485 transceiver
    • Integrated oscillator driver for external transformer
    • PROFIBUS® compliant
    • Complies with ANSI/TIA/EIA RS-485-A-98 and ISO 8482:1987(E)
    • Data rate: 16 Mbps
    • 5 V or 3.3 V operation (VDD1)
    • High common-mode transient immunity: >25 kV/μs
    • Wide-body, 16-lead SOIC package
    • 50 nodes on bus
    • Isolated DE OUT status output
    • Thermal shutdown protection
    • Safety and regulatory approvals
      UL recognition: 2500 V rms for 1 minute per UL 1577
      VDE Certificate of Conformity
      DIN V VDE V 0884-10 (VDE V 0884-10):2006-12
      Reinforced insulation, VIORM = 560 V peak
    • Operating temperature range: –40°C to +85°C

    Verified Circuits Using This Part

    Verified Circuits are designed for ease of use and proven to work by ADI applications engineers. To learn more about Verified Circuits from ADI, please visit Verified Circuits Home.

    Circuit Diagram

    Diagrams

    ADM2485 Diagram
    Functional Block Diagram for ADM2485

    Specifications

    Protocols RS-422,RS-485
    Pwr Supply (Vnom) +3 to +5 & ISO +5
    #Tx 1
    # Rx 1
    Data Rate 16Mbps
    Low Power Shutdown No
    Operating Temp Range -40 to +85

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