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

Package Options

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

8.2.1 Sinking Type Digital Inputs

Figure 8-2 shows the implementation of sinking type digital inputs. INx pins are connected to the digital inputs through RTHR resistors in the range of 180Ω to 2.4kΩ. RTHR resistors determine voltage transition thresholds at the module input. RTHR resistors attenuate the surge current flowing into ISO1228 when surge-proof pulse load resistors are used. The resistor RILIM controls the current limit of all eight channels. CSURGE value is set to 4.7µF. CFIL value is set to 1nF. RSURGE and RILIM surge-proof resistors are on the AVCC path.

The resistor RSURGE is chosen to filter surges on the V24V module supply. A larger value of RSURGE provides better filtering. The capacitor CSURGE = 4.7μF is used to filter surge voltages and any other noise present on the field supply. CFIL provides local decoupling to the IC and must be of 1nF value. CFIL must be placed as close to IC as possible. RSURGE, CFIL , and CSURGE are all required for the proper functioning of the current limit function. RSURGE, RTHR, RILIM, and RPAR can be selected from Voltage Thresholds for IEC 61131-2 Type 1, 2, 3 Isolated Digital Inputs

The capacitor CIN can be optionally used to filter noise on INx pins. A value of 100pF to 10nF can be used depending on the module data rate. Include a footprint for CIN in the layout, and use the footprint if needed, based on test results.

ISO1228 Sinking Type Digital Inputs With ISO1228Figure 8-2 Sinking Type Digital Inputs With ISO1228