SLLS665M September   2005  – February 2023 SN65HVD30 , SN65HVD31 , SN65HVD32 , SN65HVD33 , SN65HVD34 , SN65HVD35

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
    1.     6
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics: Driver
    6. 7.6  Electrical Characteristics: Receiver
    7. 7.7  Device Power Dissipation – PD
    8. 7.8  Supply Current Characteristics
    9. 7.9  Switching Characteristics: Driver
    10. 7.10 Switching Characteristics: Receiver
    11. 7.11 Dissipation Ratings
    12. 7.12 Typical Characteristics
      1.      Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Low-Power Standby Mode
      2. 8.3.2 Driver Output Current Limiting
      3. 8.3.3 Hot-Plugging
      4. 8.3.4 Receiver Failsafe
      5. 8.3.5 Safe Operation With Bus Contention
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 Data Rate and Bus Length
        2. 9.2.1.2 Stub Length
        3. 9.2.1.3 Bus Loading
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.5 Safe Operation With Bus Contention

These devices incorporate a driver current limit of 250 mA across the RS-485 common-mode range of –7 V to +12 V. As stated in the Application Guidelines for TIA/EIA-485-A(1), this sets a practical limitation to prevent damage during bus contention events. Contention can occur during system initialization, during system faults, or whenever two or more drivers are active at the same time.

Figure 8-3 shows a 2-node system to demonstrate bus contention by forcing both drivers to be active in opposing states.

GUID-56F50EA5-5705-4CEE-9E96-C476A90CBA15-low.gifFigure 8-3 Bus Contention Example

Figure 8-4 shows typical operation in a bus contention event. The bottom trace illustrates how the SN65HVD33 device at Node 1 continues normal operation after a contention event between the two drivers with a –7-V ground offset on Node 2. This illustrates how the SN65HVD3x family of devices operates robustly in spite of bus contention faults, even with large common-mode offsets.

GUID-3C9E45ED-D455-4F0C-AADD-A62C2E332D59-low.gifFigure 8-4 SN65HVD3x Drivers Operate Correctly After Bus Contention Faults
1. TIA/EIA Telecommunications System Bulletin TSB89, Application Guidelines for TIA/EIA-485-A