SLLSFF7A may   2021  – december 2021 ISOW1044

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Description Continued
  7. 6 Device Comparison Table
  8. 7 Pin Configuration and Functions
  9. 8 Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  ESD Ratings
    3. 8.3  Recommended Operating Conditions
    4. 8.4  ThermalInformation
    5. 8.5  Power Ratings
    6. 8.6  Insulation Specifications
    7. 8.7  Safety-Related Certifications
    8. 8.8  Safety Limiting Values
    9. 8.9  Electrical Characteristics
    10. 8.10 Supply Current Characteristics
    11. 8.11 Switching Characteristics
    12. 8.12 Insulation Characteristics Curves
    13. 8.13 Typical Characteristics
  10. 9 Parameter Measurement Information
  11. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Power Isolation
    3. 10.3 Signal Isolation
    4. 10.4 CAN Transceiver
      1. 10.4.1 Remote Wake Request via Wake-Up Pattern (WUP) in Standby Mode
    5. 10.5 Functional Block Diagram
    6. 10.6 Feature Description
      1. 10.6.1 CAN Bus States
      2. 10.6.2 Digital Inputs and Outputs: TXD (Input) and RXD (Output)
      3. 10.6.3 TXD Dominant Timeout (DTO)
      4. 10.6.4 Power-Up and Power-Down Behavior
      5. 10.6.5 Protection Features
      6. 10.6.6 Floating Pins, Unpowered Device
      7. 10.6.7 Glitch-Free Power Up and Power Down
    7. 10.7 Device Functional Modes
    8. 10.8 Device I/O Schematics
  12. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Bus Loading, Length and Number of Nodes
        2. 11.2.2.2 CAN Termination
      3. 11.2.3 Application Curve
      4. 11.2.4 Insulation Lifetime
  13. 12Power Supply Recommendations
  14. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  15. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Receiving Notification of Documentation Updates
    3. 14.3 Support Resources
    4. 14.4 Trademarks
    5. 14.5 Electrostatic Discharge Caution
    6. 14.6 Glossary
  16. 15Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

11.2.2.1 Bus Loading, Length and Number of Nodes

The ISO 11898-2 Standard specifies a maximum bus length of 40 m and maximum stub length of 0.3 m. However, with careful design, users can have longer cables, longer stub lengths, and many more nodes to a bus. A large number of nodes requires transceivers with high input impedance such as the ISOW1044 transceiver.

Many CAN organizations and standards have scaled the use of CAN for applications outside the original ISO 11898-2 Standard. These organizations and standards have made system-level trade-offs for data rate, cable length, and parasitic loading of the bus. Examples of some of these specifications are ARINC825, CANopen, DeviceNet, and NMEA2000.

The ISOW1044 device is specified to meet the 1.5-V requirement with a 50-Ω load, incorporating the worst case including parallel transceivers. The differential input resistance of the device is a minimum of 30 kΩ. If 100 ISOW1044 transceivers are in parallel on a bus, this requirement is equivalent to a 300-Ω differential load worst case. That transceiver load of 300 Ω in parallel with the 60 Ω gives an equivalent loading of 50 Ω. Therefore, the ISOW1044 device theoretically supports up to 100 transceivers on a single bus segment. However, for CAN network design margin must be given for signal loss across the system and cabling, parasitic loadings, network imbalances, ground offsets and signal integrity, therefore a practical maximum number of nodes is typically much lower. Bus length may also be extended beyond the original ISO 11898 standard of 40 m by careful system design and data-rate tradeoffs. For example, CAN open network design guidelines allow the network to be up to 1 km with changes in the termination resistance, cabling, less than 64 nodes, and a significantly lowered data rate.

This flexibility in CAN network design is one of the key strengths of the various extensions and additional standards that have been built on the original ISO 11898-2 CAN standard. Using this flexibility requires the responsibility of good network design and balancing these tradeoffs.