SLLA628 September   2023 THVD1424

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Use Case Domain of RS-485
    1. 1.1 RS-485 Compliant Transmitter
    2. 1.2 RS-485 Compliant Receiver
    3. 1.3 RS-485 Transceiver Use Case Variability
  5. 2Traditional RS-485 Design Process
    1. 2.1 Design Process Overview
    2. 2.2 Requirement Definition
      1. 2.2.1 Bus Voltage and Logic Voltage (VCC and VIO):
      2. 2.2.2 Number of Communication Nodes Supported plus Static vs. Dynamic Systems
      3. 2.2.3 Max Bus Length, Network Topology, Emission Concerns, and Data Rate Required
      4. 2.2.4 Duplex
      5. 2.2.5 Protection Needs
      6. 2.2.6 Additional Features of RS-485 Bus
    3. 2.3 IC Selection, Application Design, and Validation/Qualification
  6. 3One Multi-System Design: Flexible RS-485 with the THVD1424
    1. 3.1 Flexible Multi-System Design
    2. 3.2 Simplification of RS-485 Design Process Using THVD1424
      1. 3.2.1 Bus Voltage and Logic Voltage Supplies (VCC and VIO)
      2. 3.2.2 Number of Communication Nodes Supported plus Dynamic or Static Systems
      3. 3.2.3 Max Bus Length, Network Topology, Data Rate, and Emissions Concerns
      4. 3.2.4 Duplex
      5. 3.2.5 Protection Needs
      6. 3.2.6 Additional Features
  7. 4Summary
  8. 5References

3.2.4 Duplex

The next issue is that of the duplex of the system. Traditionally the choice is either half or full duplex without additional components. The THVD1424 doesn’t have this limitation as through a simple logic pin the device can be configured into a half or full duplex communication mode without the need for additional circuitry. One concern can be: Half Duplex devices are typically smaller than full-duplex – why would the design include a full-duplex capable part if it only ever needs a half-duplex device? This is a legitimate concern – however the THVD1424 was designed with this concern in mind by releasing the part in a VQFN package that is only 3 mm x 3 mm compared to a traditional half duplex device in an 8-pin SOIC package which is at 4.9 mm x 6 mm – which is a little over 3x reduction in footprint size.

GUID-20230911-SS0I-RNJN-HVJD-B2VCJDMTPHW7-low.png Figure 3-1 Standard Half Duplex RS-485 IC Package vs. THVD1424 Package