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

10.6.4 Power-Up and Power-Down Behavior

The ISOW1044 has built-in under-voltage lockout (UVLO) on all supplies (VDD, VIO and VISOOUT) with positive-going and negative-going thresholds and hysteresis. Both the power converter supply (VDD) and Logic supply (VIO) need to be present for the device to work. If either of them is below its UVLO, both the signal path and the power converter are disabled.

Assuming VIO is above its UVLO+, when the VDD voltage crosses the positive-going UVLO threshold during power-up, the DC-DC converter initializes and the power converter duty cycle is increased in a controlled manner. This soft-start scheme limits primary peak currents drawn from the VDD supply and charges the VISOOUT output in a controlled manner, avoiding overshoots. CAN BUS is in high impedance state in this duration. When the UVLO positive-going threshold is crossed on the secondary side VISOOUT pin, the feedback channel starts providing feedback to the primary controller. The regulation loop takes over and CAN drive output, Received data output (RXD) and gneral purpose logic channel (OUT) take their respective states defined by the inputs to the device i.e. Standby (STB), Driver data to be transmitted TXD, and general purpose logic input IN respectively. Designers should consider a sufficient time margin (typically 5 ms with 10-µF load capacitance) to allow this power up sequence before any usable system functionality.

When either of VDD or VIO is lost, the primary side DC-DC controller turns off when the UVLO lower threshold is reached. The VISOOUT capacitor then discharges depending on the isolation channels and BUS load.