SLLSFS1B August   2023  – April 2024 THVD4431

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  ESD Ratings [IEC]
    4. 5.4  Recommended Operating Conditions
    5. 5.5  Thermal Information
    6. 5.6  Power Dissipation
    7. 5.7  Electrical Characteristics
    8. 5.8  Switching Characteristics_RS-485_500kbps
    9. 5.9  Switching Characteristics_RS-485_20Mbps
    10. 5.10 Switching Characteristics, Driver_RS232
    11. 5.11 Switching Characteristics, Receiver_RS232
    12. 5.12 Switching Characteristics_MODE switching
    13. 5.13 Switching Characteristics_RS-485_Termination resistor
    14. 5.14 Switching Characteristics_Loopback mode
    15. 5.15 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Integrated IEC ESD and EFT Protection
      2. 7.3.2 Protection Features
      3. 7.3.3 RS-485 Receiver Fail-Safe Operation
      4. 7.3.4 Low-Power Shutdown Mode
      5. 7.3.5 On-chip Switchable Termination Resistor
      6. 7.3.6 Operational Data Rate
      7. 7.3.7 Diagnostic Loopback
      8. 7.3.8 Integrated Charge pump for RS-232
    4. 7.4 Device Functional Modes
      1. 7.4.1 RS-485 Functionality
      2. 7.4.2 RS-232 Functionality
      3. 7.4.3 Mode Control
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Data Rate and Bus Length for RS-485
        2. 8.2.1.2 Stub Length for RS-485 Network
        3. 8.2.1.3 Bus Loading for RS-485 Network
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    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 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    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

7.3.7 Diagnostic Loopback

THVD4431 provides complete path diagnostic loopback modes for both RS-232 and RS-485. These modes internally short bus outputs to bus inputs. So, if data is toggled from logic input, data reaches bus and is reflected back on logic buffer output. This enables MCU to detect bus side short (due to connector/cable) by comparing logic input and logic output.

In RS-232 loopback mode, L3 reflects on L2/R2/R3; L4 reflects on L1/R4/R1; L6 reflects on L5, L7, L8, R5, R6, R7 and R8 enabling to detect short to ground on all bus pins from R1 through R8. RS-232 loopback mode is optimized for -40°C to 85°C ambient temperature. RS-232 diagnostic loopback can be performed on a node (DUT1) even with another node (DUT2) connected via cable, but listening node (DUT2) is not allowed to transmit anything on the RS232 lines while loopback check by DUT1 is ongoing.

In RS-485 loopback mode, internally R2 gets connected to R3 and R1 gets connected to R4. L3 input data is routed to driver output terminals and receiver input terminals and reflects on L2. DIR and TERM_RX are not supported in this mode. Specific to this mode, external termination on R3/R4 is not supported, but R1/R2 can have internal or external termination. This is able to detect short between R1/R2 and between R3/R4 bus terminals. Recommended maximum data rate for RS-485 diagnostic loopback to detect cable or connector shorts is 500kbps with SLR = VIO.