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

7.3.5 On-chip Switchable Termination Resistor

THVD4431 has 2 termination resistors of nominal 120 Ω, one across R1/R2 and another across R3/R4 in RS-485 mode. Both termination resistors are enabled or disabled using pins as described in Table 7-2. Both the termination resistors can be enabled or disabled independent of the state of driver or receiver. Termination is OFF in RS-232 loopback, RS-232 3T5R, RS-485 loopback, unpowered and thermal shutdown modes.

Table 7-2 On-chip Termination Function
Signal stateDevice modeFunctionComments
TERM_TX = VIOFull duplex mode120 Ω enabled between R1 and R2Termination between R1/R2 is disabled by default
TERM_TX = GND or floatingFull duplex mode120 Ω disabled between R1 and R2
TERM_RX = VIOFull duplex mode120 Ω enabled between R3 and R4Termination between R3/R4 is disabled by default
TERM_RX = GND or floatingFull duplex mode120 Ω disabled between R3 and R4
TERM_RX = X, TERM_TX = VIOHalf duplex mode120 Ω enabled between R1 and R2In half duplex mode, TERM_RX is don't care and TERM_TX has higher priority
TERM_RX = X, TERM_TX = GNDHalf duplex mode120 Ω disabled between R1 and R2

The on-chip 120 Ω termination resistor is designed for minimum variation across temperature and across common mode voltage on bus pins. The termination block offers a resistive load to the bus, and does not alter the magnitude or phase of the bus signals from DC to 20Mbps signaling. See the typical characteristic curves for variation of termination resistor with voltage and temperature.