SLLSF21D September   2018  – February  2020

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Power Ratings
    6. 6.6  Insulation Specifications
    7. 6.7  Safety-Related Certifications
    8. 6.8  Safety Limiting Values
    9. 6.9  Electrical Characteristics: Driver
    10. 6.10 Electrical Characteristics: Receiver
    11. 6.11 Supply Current Characteristics: Side 1(ICC1)
    12. 6.12 Supply Current Characteristics: Side 2(ICC2)
    13. 6.13 Switching Characteristics: Driver
    14. 6.14 Switching Characteristics: Receiver
    15. 6.15 Insulation Characteristics Curves
    16. 6.16 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Electromagnetic Compatibility (EMC) Considerations
      2. 8.3.2 Failsafe Receiver
      3. 8.3.3 Thermal Shutdown
      4. 8.3.4 Glitch-Free Power Up and Power Down
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device I/O Schematics
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Data Rate and Bus Length
        2. 9.2.2.2 Stub Length
        3. 9.2.2.3 Bus Loading
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 PCB Material
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resource
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.1 Application Information

The ISO1500 device is designed for bidirectional data transfer on multipoint RS-485 networks. The design of each RS-485 node in the network requires an ISO1500 device and an isolated power supply as shown in Figure 32.

An RS-485 bus has multiple transceivers that connect in parallel to a bus cable. Both cable ends are terminated with a termination resistor, RT, to remove line reflections. The value of RT matches the characteristic impedance, Z0, of the cable. This method, known as parallel termination, lets higher data rates be used over a longer cable length.

In half-duplex implementation, as shown in Figure 31, the driver and receiver enable pins let any node at any given moment be configured in either transmit or receive mode which decreases cable requirements.

ISO1500 iso1500-half-duplex-network-circuit.gifFigure 31. Half-Duplex Network Circuit