SLLA637 May   2024 THVD4431

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Key Feature Highlights of THVD4431 Over XR34350 and SP339E/B
    1. 2.1 Regulated Output Voltage for RS-232
    2. 2.2 Full Path Diagnostic Loopback
    3. 2.3 Operating Ambient Temperature Range
    4. 2.4 Integrated Switchable Termination Resistor on Both Driver (R1/R2) and Receiver (R3/R4) Bus Pins
    5. 2.5 1.65V to 5.5V Supply for Logic Data and Control Signals
  6. 3Potential Design Changes
    1. 3.1 Pin 9 (VIO)
    2. 3.2 Pin 13 (MODE2)
    3. 3.3 Pin 17 (TERM_TX) and Pin 18 (TERM_RX)
    4. 3.4 Pin 19 (SHDN)
    5. 3.5 Pin 36 (NC)
  7. 4Pinout Mapping
  8. 5Summary
  9. 6References

3.3 Pin 17 (TERM_TX) and Pin 18 (TERM_RX)

As described earlier in this document, TI’s THVD4431 provides 2 on-chip 120Ω termination resistors: one across the R1/R2 terminals (controlled by pin17 TERM_TX and is used in both RS-485 half duplex and full duplex modes), the other across the R3/R4 terminals (controlled by pin18 TERM_RX and is used in RS-485 full duplex mode).

Refer to Table 3-1 for a way to configure these pins the same as the XR34350 and SP339E/B devices.

Table 3-1 Pin 17 and Pin 18 Configuration for THVD4431 to Match XR34350 Functionality
Pin 17 TERM_TX Pin 18 TERM_RX
RS-485 half duplex Pull up to VIO to enable termination across R1/R2 or pull-down to GND to disable NC
RS-485 full duplex NC Pull up to VIO to enable termination across R3/R4 or pull-down to GND to disable