SLLSFN5B June   2023  – September 2025 ISO1228

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Power Ratings
    6. 5.6  Insulation Specifications
    7. 5.7  Safety-Related Certifications
    8. 5.8  Safety Limiting Values
    9. 5.9  Electrical Characteristics—DC Specification
    10. 5.10 Switching Characteristics—AC Specification
    11. 5.11 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Test Circuits
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Surge Protection
      2. 7.3.2  Field Side LED Indication
      3. 7.3.3  Serial and Parallel Output option
      4. 7.3.4  Cyclic Redundancy Check (CRC)
      5. 7.3.5  FAULT Indication
      6. 7.3.6  Digital Low Pass Filter
      7. 7.3.7  SPI Register Map
      8. 7.3.8  SPI Timing - Non-Daisy Chain
      9. 7.3.9  SPI Timing - Daisy Chain
      10. 7.3.10 SPI Timing - Burst Mode
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Sinking Type Digital Inputs
      2. 8.2.2 Sourcing Type Digital Inputs
      3. 8.2.3 Sink/Source Type Digital Inputs
      4. 8.2.4 Design Requirements
        1. 8.2.4.1 Detailed Design Procedure
          1. 8.2.4.1.1 Current Limit
          2. 8.2.4.1.2 Voltage Thresholds
          3. 8.2.4.1.3 Wire-Break Detection
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.1 Overview

The ISO1228 device is an eight channel fully-integrated, isolated digital-input receiver with 61131-2 Type 1, 2, and 3 characteristics.The device receives 0V to 36V digital-input signals and provides isolated digital outputs on the MCU/backplane side.An external resistor, RILIM, in the AVCC supply path, precisely sets the limit for the current drawn from each digital input.An external resistor, RILIM, precisely sets the limit for the current drawn from each digital input. The current limit is common to all channels. Resistors RPAR must be included between each INx and the corresponding LEDx pins to have a flat current limit feature. The voltage transition thresholds are compliant with Type 1, 2, and 3 and can be increased further using external resistors, RTHR.For more information on selecting the RILIM, RSURGE, RPAR and RTHR resistor values, see the Detailed Design Procedure section. The current drawn from the digital inputs is diverted to LEDx pins, once the digital input crosses the input voltage threshold. This feature allows field-side LED indication with no additional power consumption. ISO1228 can be configured for either sinking or sourcing type digital inputs.

The ISO1228 serializes data from all eight digital inputs and transfers the data across the isolation barrier. The device supports wire-break detection, field side supply monitoring, and internal CRC for across barrier communication.

The ISO1228 supports a wide supply voltage range of 1.71V to 5.5V on the logic side. The conceptual block diagram of the ISO1228 is shown in the Functional Block Diagram section.