SBAS738A June   2018  – October 2018 ISO224

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Power Ratings
    6. 7.6  Insulation Specifications
    7. 7.7  Safety-Related Certifications
    8. 7.8  Safety Limiting Values
    9. 7.9  Electrical Characteristics
    10. 7.10 Switching Characteristics
    11. 7.11 Insulation Characteristics Curves
    12. 7.12 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
      2. 8.3.2 Input Clamp Protection Circuit
      3. 8.3.3 Isolation Channel Signal Transmission
      4. 8.3.4 Fail-Safe Output
    4. 8.4 Device Functional Modes
  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
      3. 9.2.3 Application Curves
    3. 9.3 What to Do and What Not to Do
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    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 Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.3.4 Fail-Safe Output

The ISO224 offers a fail-safe output that simplifies diagnostics on system level. The fail-safe output is active when the high-side power supply VDD1 of the device is missing, independent of the input signal at the IN pin. Figure 46 shows that in that case both outputs, OUTP and OUTN, of the device are actively driven close to GND2 (see the VFAILSAFE specification in the Electrical Characteristics table for details). For easy visualization, an example with the input signal VIN = 0 V is shown for the valid VDD1 range of 4.5 V to 5.5 V.

ISO224 ai_failsafe_bas738.gifFigure 46. ISO224 Failsafe Output Behavior With VIN = 0 V

The ISO224 Fail-Safe Output Feature application report describes an example of a comparator-based circuit that detects the missing high-side supply in a system.